Human Reproduction.

Human Reproduction

The Nucleus One organelle inside each cell of an organism is the nucleus. The nucleus is the largest organelle and is usually found close to the center of a cell. It is responsible for holding the DNA that codes for all genetic traits and controls the function of each cell.

Chromosomes Graphic representation Real picture

DNA Chromosomes are tightly coiled double strands of DNA (deoxyribonucleic acid) called a double helix. DNA is the material that transfers genetic characteristics in all life forms, constructed of two nucleotide strands coiled around each other in a ladder-like arrangement with bases forming the steps of the ladder.

DNA The genetic information of DNA is encoded in the sequence of the bases and is copied when the strands unwind and replicate. There are four main bases called adenine, thymine, cytosine, and guanine. The arrangement of these bases created genes. Bases are ‘read’ by RNA in groups of 3. Ex. CCG ATA TTC

Genes A part of DNA that instructs the nucleus to create a particular protein which determines particular traits. These traits may be structural like skin pigment or functional like growth rate. Each segment of DNA (gene) will code for different traits. (see the human genome map). A genome is all the genetic information stored within all the chromosomes of a living cell. There are generally two types of gene in each individual called alleles and these are either two dominant alleles, one dominant and one recessive, or two recessive.

Analogy A good analogy to remember:
Think of the sequence of bases on DNA like words, genes like sentences, chromosomes like chapters, and the book like the whole human genome. (all the chromosomes together that make you what you are.)

The Cell Cycle The cell cycle is a continuous process of cell life and division that consists of interphase, the four phases of cell division (prophase, metaphase, anaphase, and telophase) PMAT, and cytokenesis.

The Cell Cycle

Interphase This is also called the growth phase (G).
The cell will spend most of its time in this phase. This is the time when the cell grows and functions as it should. Near the end of this phase the chromosomes will unwind and be copied (replicated). The chromosomes are not visible now as they are all unwound. They are called chromatin now.

Interphase

Mitosis Mitosis is the process of creating 2 new body cells from one cell. This process creates clones or identical copies of the original cell which are called daughter cells. This is an ongoing process that allows the body to grow and replace dying cells.

Mitosis Not all cells reproduce new cells at the same rate. Ex skin renews every days where nerve cells rarely reproduce. This is exponential growth.

Prophase Chromatin condenses into chromosomes that you can see with a microscope. Chromosomes are formed from the two copies being held together in the middle. The nucleolus and nuclear membrane start to disappear. Spindle fibers form and start to reach out for the chromosomes.

Metaphase Nucleus completely disappears.
The chromosomes are lined up at the center of the cell by the spindle fibers.

Anaphase Each set of chromosomes are pulled to the poles of the cell.
Some cytokinesis begins. Cytokinesis is the dividing of the cell cytoplasm.

Telophase Nuclear membrane and nucleolus return.
Nuclear membrane and nucleolus return. Cytokinesis is completed. Chromosomes unwind and form chromatin again.

Cytokinesis Division of the cytoplasm into 2 daughter cells.
Replicating of new organelles also occurs. In plants a cell plate forms between the 2 daughter cells to form a new cell wall.

Meiosis The process of producing haploid gametes. Gametes are eggs and sperm. Meiosis only occurs in Spermatogonia (male) and Oogonia (female). Haploid (n) means ½ the number of chromosomes. Diploid (2n) means having all the chromosomes of your species. Cell division occurs twice but with only one replication. Shuffling of genetic material from both parents produces variety and diversity.

Meiosis As with mitosis, the first step in this process is DNA replication, so that each of the 46 chromosomes exists as a duplicated sister chromatid. This occurs in the S phase just as in mitosis. Unlike mitosis the chromosomes pair up in homologous chromosomes. This is called synapsis. That is the two pairs of chromosomes with similar traits are paired such that tetrads form and 23 will be lined up in metaphase.

Meiosis Homologous chromosomes, or homologues, are pairs of chromosomes very similar in size, shape, and gene sequence, that interact during meiosis. Sex chromosomes in a cell also interact during meiosis and are considered homologues. They have the same genes but may have different forms of the genes (called alleles). This is VERY IMPORTANT in creating variation among individuals of the same species.

Meiosis Ex: gene for eye colour may be a brown allele on one chromosome and a blue allele on the other. Humans have 23 pairs of homologous chromosomes. Synapsis the pairing of homologous chromosomes in prophase I. Tetrad a homologous pair of chromosomes formed from 4 chromatids.

Meiosis Autosomal chromosome non-sex chromosomes Sex chromosome
either an X or a Y chromosome that determines the sex of an organism. humans have either XX (girl) or XY (boy).

Meiosis During the first stage of meiosis, an unusual - and vitally important - event occurs: Crossing Over. Pieces of DNA are swapped between non-sister chromatids, resulting in new never before chromosome combinations.

Meiosis Crossing Over an exchanging of segments of chromosomes between non-sister chromosomes. These segments may contain 100's or 1000's of genes. This allows for different combinations of genes to be passed on to offspring. Genetic material in a new individual is therefore a mixture of maternal (mother’s) and paternal (father’s) genes from one chromosome.

Meiosis Crossing Over This is VERY IMPORTANT in creating variation among individuals of the same species. Without crossing over a chromosome and all its genes would either be maternal or paternal origin not a mixture of both. Ex. found on page 473 of the text.

Crossing over THIS PROCESS GENERATES THE DIVERSITY OF ALL SEXUALLY REPRODUCING ORGANISMS.

Meiosis Prophase I 4 original chromosomes.
Note the tetrads (4 chromosomes) Rest is the same as mitosis.

Meiosis Metaphase I Tetrads are pulled to the equator of the cell by spindle fibers.

Meiosis Anaphase I Sister chromatids remain together and are pulled to the poles of the cell.

Meiosis Telophase I After cytokinesis, each of the two progeny cells has a nucleus with a haploid set of replicated chromosomes.

Meiosis animation

Meiosis Prophase II NO REPLICATION OCCURS PRIOR TO THIS STAGE.
As in mitosis centrioles duplicate and move to the poles, spindle fibers form, nuclear membrane disappears. NOTE: THERE ARE TWO CELLS DIVIDING NOW!!!

Meiosis Metaphase II Sister chromatids line up on the equator much like mitosis. Maternal and paternal chromosomes can be distributed on either side of the cell, thus adding to the mixing of genetic material. Possible combinations are 223

Meiosis Anaphase II The centromeres separate and the sister chromatids—now individual chromosomes—move toward the opposite poles of the cell.

Meiosis Telophase II A nuclear envelope forms around each set of chromosomes and cytokinesis occurs, producing four daughter cells, each with a haploid set of chromosomes.

A Comparision MITOSIS MEIOSIS In body cells In sex cells
Two daughter cells produced Four daughter cells produced Diploid cells produced Haploid cells produced Same number of chromosomes as the original cell One half the number of chromosomes as the original cell Asexual reproduction Sexual Reproduction

Gametogenesis (Sperm and egg formation)
Meiosis to produce sperm and egg are slightly different. In sperm cells the 4 haploid cells are further developed with tails (called flagella) to aid in movement. In egg cells during meiosis I and II the cytoplasm is unevenly divided giving one haploid cell the majority. The other cell called a polar body dies off. Therefore only one egg is produced from every meiotic division.

Spermatogenesis -The production of sperm by the male reproductive organs (testes) through meiosis. -Starts with a diploid spermatogonium (cells in the testes) that undergoes meiosis to produce 4 haploid sperm cells. -Some organisms, like humans, produce sperm all the time. -Some organisms only produce sperm during a breeding season.

Each sperm cell produced has the chromosome number and 1/4 the cytoplasm of the original spermatogonium. Sperm cells may contain an X chromosome OR a Y sex chromosome. SEE DIAGRAM OF SPERMATOGENESIS PAGE 477 AND DRAW YOUR OWN DIAGRAM.

after meiosis I and meiosis II the nucleus forms the head of the sperm, the cytoplasm is reduced, and a tail-like flagellum forms for movement. Sperm are relatively small compared to an egg because its only function is to deliver DNA to the egg and it must travel a long way. -sperm have a large reserve of fat and numerous mitochondria to process these reserves to drive the flagellum. Semen also provides energy in the form of fructose (a sugar) to sustain the mitochondria.

human males produce 300 to 500 million sperm every day.
sperm can survive in the uterus about 2 to 4 days. sperm have a cap on the head called an acrosome. This contains enzymes which dissolve the outer coating of the egg so the sperm can enter. KNOW THE CHART ON PAGE 478. DRAW A SPERM AND ITS PARTS HERE.

Spermatogenesis

Animation http://www.youtube.com/watch?v=D1_-mQS_FZ0

Male Reproductive System
Begins to form in the fetus at 8 weeks. It is functional at the end of puberty (~ 13 years of age) Produces sperm from puberty to death 24/7 Semen contains ~ 500 million sperm per ejaculation (120/ml of semen with 2-6 ml/ejaculation)

Testes Usually two that descend into the scrotum during the 8-9 month of fetal development. Failure to descend can cause sterility but can be corrected with surgery. Composed of long coiled seminiferous tubules. Responsible for sperm production. ( 5% of the volume of semen)

Testes: Seminiferous Tubules
Found in the testes and are as much as 250 m long. Spermatogenesis and mitosis occurs within the lining of these tubules. Sperm production progresses from the outside wall of the tubules toward the inside with the lumen ( empty space in the center) carries the partially developed sperm to the epididymis.

Interstitial (leydig) cells are found between the seminiferous tubules and secrete testosterone.

Testes: Seminiferous Tubules
Sertoli Cells these cells are found within the seminiferous tubules and are responsible for structural and metabolic support to the developing sperm cells. They are also responsible for releasing the hormone Inhibin. Inhibin is responsible for blocking the release of FSH (follicle stimulating hormone)

Testes: Interstitial Cells
Interstitial Cells or Leydig cells these cells are found between and surrounding the seminiferous tubules and are responsible for secreting testosterone.

Testes: Interstitial Cells
Testosterone is a hormone that is responsible for secondary male characteristics including: enlargement of the primary sexual characteristics (penis and testes) and larynx, stimulation of hair and muscle growth, and inhibition of fat production. It maintains these characteristics, as well as sperm production, and sexual desire. In some species it is also responsible for aggression. It also acts in a negative feedback loop to inhibit LH so that the correct amount of testosterone can be maintained.

Sertoli cells are found within the seminiferous tubules and support the development of sperm AND release Inhibin. Inhibin acts as a negative feedback mechanism to slow down the production of FSH.

Seminiferous Tubule cross-sectional

Epididymis an area attached to each testis that stores sperm and completes their maturation.

Scrotum A sac that holds the testes outside the body in order to keep the sperm cooler (35⁰C) this keeps sperm alive and healthy. The temperature can be adjusted slightly in the scrotum by the contraction/relaxation of smooth muscles to tighten/loosen the walls.

Vas deferens (sperm duct)
a long tube attached to the epididymis of each testis and connecting it with the ejaculatory duct.

Seminal Vesicle this organ is located to the posterior of the bladder and connected to the vas deferens. It produces a mucous-like fluid that contains the sugar fructose which will provide energy for the mitochondria of the sperm and allow them to move. It also causes the semen to clot or thicken to keep it in the vagina. (45-80% of the whole volume of semen)

Ejaculatory Duct Urethra
a short duct that connects the vas deferens to the urethra just below the seminal vesicles. Urethra a tube connecting the bladder to the penis. A valve shuts off the urethra above the ejaculatory duct when sexually aroused.

Bulbourethral Gland (Cowper’s gland)
this gland is located along the urethra below the bladder and secretes an alkaline fluid to add to the semen. This fluid neutralizes the acids in the female reproductive tract and protects the sperm from damage and it lubricates the male reproductive tract. (2-5% of the volume of semen)

Prostate Gland also located next to the urethra and below the bladder. It also adds alkaline fluid to the semen. It also produces a chemical to liquify the clotted semen so sperm can swim away (15-30% of the volume of semen)

Penis external sex organ made of spongy venous tissue that can be engorged with blood to increase its size and create a stiff organ to insert into the vaginal opening. It main purpose is to carry semen to the vagina and to carry urine out of the body. Both these activities DO NOT occur at the same time.

MALE REPRODUCTIVE HORMONES
Negative Feedback Loop: The increase of one chemical (usually a hormone) causes a decrease in another chemical (usually another hormone). involves a homeostatic process that can detect and reverse shifts from the normal levels of a chemical in the body.

Glands involved Hypothalamus Pituitary
A portion of the brain that links the nervous systems, endocrine systems, and the body. It works by monitoring blood hormone levels and sending a response to the pituitary gland Pituitary Another small “Master gland” in the brain that controls the release of a number of hormones that control the body.

Hormones involved Gonadotropin-releasing Hormone (GnRH) a hormone secreted by the hypothalamus that directly stimulates the pituitary gland to secrete gonadotrophins. The gonadotrophins are follicle stimulating hormone (FSH) and luteinizing hormone (LH).

Hormones involved Follicle-Stimulating Hormone (FSH) secreted by the anterior pituitary gland in the brain stimulates the spermatogonia to produce sperm cells. It also stimulates Sertoli cells to produce Inhibin.

Hormones involved Inhibin is secreted by the Sertoli cells in the testes and act as a feedback to block FSH production. This negative feedback loop keeps the FSH at normal levels. Luteinizing Hormone (LH) secreted by the anterior pituitary gland in the brain stimulates the interstitial cells of the testes to produce the male sex hormones, the main one being testosterone.

Hormones involved Testosterone is a hormone that is responsible for secondary male characteristics including: enlargement of the primary sexual characteristics (penis and testes) and larynx, stimulation of hair and muscle growth, and inhibition of fat production. It maintains these characteristics, as well as sperm production, and sexual desire. In some species it is also responsible for aggression. It also acts in a negative feedback loop to inhibit LH so that the correct amount of testosterone can be maintained.

Male hormones

Then there were girls!!!!

Female Reproductive System
Forms in the fetus at about 8 weeks (same as the male) Functional at the end of puberty (~ 10 years old in N. America) One egg is released once every 28 days (approx) Eggs are only released from about age 13 to age (very approx) when menopause ends the cycle.

Oogenesis (Egg production)
The production of eggs by the female reproductive organs (the ovaries) through meiosis. Starts with a diploid (2n) oogonium (cells in the ovaries) that undergoes meiosis to produce 1 viable egg cell (ovum). when the oogonium undergoes meiosis I an unequal division of cytoplasm occurs and one cell receives most. After the second meiotic division again one cell receives most of the cytoplasm. So one of the four (random) haploid cells receives most of the cytoplasm and forms the ovum while the other three, known as polar bodies, die and are reabsorbed.

each ovary contains 300,000 to 400,000 oogonia at puberty and normally in humans one undergoes meiosis each 28 days to produce one ovum. egg cells only have X sex chromosomes. SEE DIAGRAM OF OOGENESIS PAGE 477 AND DRAW YOUR OWN PICTURE.

the egg is relatively large compared to the sperm because it must maintain mitosis once the sperm fertilizes the egg, therefore it will need cytoplasm to divide, mitochondria to provide energy, etc. an egg survives only about one day if it is not fertilized. It must implant in the endometrium of the uterus to receive nutrition once it is fertilized. eggs CANNOT move, they are propelled down the fallopian tubes by cilia that line the tubes. the egg is covered by a special outer coating that can usually only be penetrated by a sperm of the same species. Once one sperm penetrates the surface it causes a change in the coating to prevent other sperm from entering.

Vagina Entrance for the penis to deposit sperm and an exit for the fetus during childbirth. It contains bacteria that keep other organisms from entering the uterus and causing infection. Cervix The lower neck of the uterus that opens into the vagina. It protects the uterus by acting as a barrier for larger objects.

Uterus A fist-sized thick-walled muscular organ. It is capable of stretching to six times its size to accommodate the developing fetus. It is the female reproductive organ where the fertilized egg implants. This organ houses and nourishes the developing embryo and fetus. Also called the womb. Endometrium The lining of the uterus. It has a very rich blood supply to provide nutrients to the developing fetus. The endometrium is a target organ for female reproductive hormones and will thicken or disintegrate depending on hormone and their levels (covered later in the menstrual cycle).

Oviduct normally two exist one leading from each ovary to the uterus. The lining of these tubes are ciliated to assist the egg’s travel to the uterus. Also called the fallopian tube or uterine tube. They are each about four inches long, and begin at an opening on either side of the uterus and end in a funnel that surrounds each ovary. Each tube is thin and narrow, no wider than the head of a pin. Fimbriae Near the ovary the oviduct expands to form a funnel-shaped "infundibulum," which partially encircles the ovary toward the center. On its margin the infundibulum has a number finger-like projections called "fimbriae." This is because the ovaries release ova from several openings. (Although the infundibulum generally does not touch the ovary, one of the larger extensions (the ovarian fimbria) is connected directly to it.)

Ovary normally two exist at the end of the oviduct, suspended by ligaments, in the lower abdominal cavity. Composed of follicles. They are responsible for producing ova and releasing two hormones; progesterone, estrogen, and testosterone. Follicles the ovary contains numerous follicles, each follicle contains a single ovum. Every female is born with over 2 million follicles but only about 400 will ever mature to release its ovum. The follicle goes through stages of development to produce its ovum.

Female Reproductive Organs

FEMALE REPRODUCTIVE HORMONES AND MENSES
Puberty is triggered by hormones and percent fat content of the female body. The first menstrual cycle will not begin until the female has at least 17% body fat and will stop in an already mature female if body fat drops below 22%. Secondary sex characteristics such as breast development, genital and underarm hair, widening of the hips, and increased body fat are also controlled by hormones.

Hormones involved Gonadotrophic-releasing Hormone (GnRH) a hormone secreted by the hypothalamus that directly stimulates the pituitary gland to secrete gonadotrophins. The gonadotrophins are follicle stimulating hormone (FSH) and luteinizing hormone (LH). Follicle-Stimulating Hormone (FSH) secreted by the anterior pituitary gland in the brain stimulates the follicles to produce estrogen, ripen eggs, and ready mammary glands. Luteinizing Hormone (LH) secreted by the anterior pituitary gland in the brain stimulates the follicles to release an ovum. Called ovulation. It also causes the follicle to change into the corpus luteum and produce preogesterone.

Estrogen targets the endometrium and stimulates it to thicken and increase the blood supply to prepare for pregnancy. It also acts in a negative feedback to inhibit the release of more FSH and as a positive feedback loop to stimulate the release of LH. It promotes secondary sex characteristics, regulates cervical mucus, and maintains bone density. Also produced in small amounts by the adrenal glands and liver. NOTE: Positive feedback loop a homeostatic process that can detect and increase shifts from the normal levels of a chemical in the body. The increase of one chemical (usually a hormone) causes an increase in another chemical (usually another hormone).

Progesterone is released by the corpus luteum and further prepares the uterus for pregnancy and inhibits the development of more follicles. It also inhibits the production of LH by the pituitary gland, which in turn allows the corpus luteum to degenerate and thus progesterone levels drop. Blood supply to the endometrium is decreased and menstruation begins. It also causes breast enlargement, increased appetite, increased salt and water retention, PMS, increased thickness of the cervical mucus, mood swings, and increased metabolism of fat. It also is produced in small amounts by the adrenal gland.

Prolactin is a hormone that stimulates milk production if pregnancy and birth occur.
Oxytocin is a hormone that stimulates uterine contractions during birth and milk production. Prostaglandins are involved in induction of labour and many other functions in the body.

Sites (quiz) ( info)

FO-ES L-ONE

Inside the Ovary

The Ovary Function After puberty the ovary cycles between a follicular phase (maturing follicles) and a luteal phase (presence of the corpus luteum). These cyclic phases are interrupted only by pregnancy and continue until menopause. The ovarian cycle lasts usually 28 days. During the first phase, the oocyte (EGG) matures within a follicle. At midpoint of the cycle, the oocyte is released from the ovary in a process known as ovulation. Following ovulation the follicle forms a corpus luteum which synthesizes hormones to prepare the uterus for pregnancy.

Female Human Hormonal Levels

WEBSITES

JOURNEY OF THE SPERM TO THE EGG
During ejaculation sperm travel from the epididymis through the vas deferens, pick up semen at the seminal vesicles, prostate gland, and bulbourethral gland. Then travel through the urethra, into the penis, and into the vagina. Once in the vagina, they travel through the cervix and uterus, and into the oviduct. If they encounter an egg in the oviduct fertilization will occur.

JOURNEY OF THE EGG http://www.pbs.org/wgbh/nova/miracle/program.html
During ovulation a secondary oocyte is released from the ovary. Finger-like projections of the oviduct called fimbriae sweep over the ovaries with cilia and move the ovum into the oviduct. More cilia lining the oviduct move the ovum along the oviduct. If sperm arrive in the oviduct the ovum will be fertilized. Whether fertilized or not the ovum will continue down to the uterus via ciliated movement. If the egg was fertilized it will implant into the endometrium. If the egg was not fertilized it will be ejected from the body with the menstrual flow.

FERTILIZATION -is the first stage of development and is defined as the union of one sperm with the egg to produce a zygote -when the head of a sperm successfully connects with an egg the acrosome releases enzymes that digest the jelly outer coating and stimulates the egg to produce an impenetrable coating so no other sperm can enter. -the sperm nucleus then unites with the egg nucleus and fertilization is complete. -the result is the zygote (fertilized egg)

MORULA After fertilization the zygote continues to be swept down the oviduct into the uterus. At this point, there exists a single cell with the potential to create an entire human being. Mitotic cell division is the next process to occur, where each cell doubles to produce another diploid cell. The zygote divides to produce two smaller cells called blastomeres roughly every 20 hours. These cells get progressively smaller until about 4 divisions have taken place resulting in 16 individual cells. This cluster of 16 cells is known as a morula and will leave the oviduct and make its way to the uterus. This division without increase in size is called cleavage. Once cleavage has begun the zygote is called an embryo (~3-4 days later). When bone cells begin to form (~ 3-4 weeks) the embryo is called a fetus.

Morula

BLASTOCYST A small cavity in the center of the cells develops , and the developing cells will grow around this. Cells are growing increasingly smaller to fit in. This new structure with a cavity in the center and the developing cells around it is known as a blastocyst. The presence of the blastocyst means that two types of cells are forming, inner cell mass growing on the interior of the cavity and cells growing on the exterior of it called the trophoblast. In 24 to 48 hours, the trophoblast begins excreting an enzyme which erodes epithelial uterine lining and creates a site for implantation.

Blastocyst

BLASTOCYST The blastocyst also secretes a hormone called human chorionic gonadotropin which in turn, stimulates the corpus luteum in the mother's ovary to continue producing progesterone (~3 wks), which acts to maintain the lining of the uterus so that the embryo will continue to be nourished. The glands in the lining of the uterus will swell in response to the blastocyst, and capillaries will be stimulated to grow in that region. This allows the blastocyst to receive vital nutrients from the mother.Note: The hormone human chorionic gonadotropin (HCG) is the substance that pregnancy tests test for the presence of.

GASTRULA During the 2nd week the cells of the blastocyst begin to specialize. This is called gastrulation and at this stage the embryo is called a gastrula. Early embryo with 3 tissue layers Cells separate into distinctive germ layers: endoderm (innermost layer), mesoderm (middle layer), and ectoderm (outer layer). This is known as differentiation -Each layer develops into different body parts Ectoderm - skin, hair, teeth, nervous system, etc. Mesoderm - circulatory system, urogenital system (kidneys, etc) skeleton, muscles, gonads, notochord, etc. Endoderm - respiratory system, lining of the digestive tract, etc.

Gastrula

Neurula Development of the nervous system.
This occurs very similarly in all vertebrates. Mesoderm cells in the gastrula form a notochord. (will form spine) The nervous tissue then develops from the ectoderm just above the notochord. The cells fold in and form a groove and finally a tube. When the tube forms this stage is called the neurula. The anterior end will later develop into the brain.

PRIMARY MEMBRANES Are not part of the embryo but support and protect the embryo. Chorion At about 6-7 days after fertilization the cells surrounding the blastocyst will destroy cells in the uterine lining forming small pools of blood, which in turn will stimulate the production of capillaries. The chorion develops, with chorionic villi (finger-like projections) from the outside layer of the blastocyst. A system of blood and blood vessels will now develop at this point forming the placenta, growing near the implantation site. For the next 24 hours, connective tissue will develop between the developing placenta and the growing fetus. This will later develop into the umbilical cord.

Amnion At the same time, the bottom layer will form a small sac (the amnion). The amnion will enclose the embryo and contains amniotic fluid that cushions against external shocks. It also prevents the embryo from sticking to the uterine wall. This sac will also begin producing its blood cells.

Placenta The placenta is a blood-rich organ that is only present during pregnancy. It is fully formed at 10 weeks and produces estrogen and progesterone to prevent follicle development and to maintain the uterus. It acts as an intermediate between the mothers blood supply and the fetus blood supply. It will deliver nutrients and oxygen to the developing fetus and remove waste and carbon dioxide from the fetus. MATERNAL AND FETAL BLOOD NEVER MIX. There exists a boundary where maternal blood vessels come close to fetal blood vessels and many viruses, bacteria, and drugs can cross into the fetal blood supply.

Umbilical Cord connection from the embryo to the placenta and transports nutrients, oxygen, carbon dioxide, and waste between the embryo and the placenta. Develops during gastrulation. Allantois a layer of the trophoblast that develops to collect waste before the placenta forms. It later develops into blood vessels of the umbilical cord.

Yolk a material that nourishes the embryo before implantation. The amount of yolk present varies from species to species depending on how long it may need nourishment before hatching, birth, or implantation. Tadpoles - very small as they hatch quickly and develop later Chicks - large yolk as they develop inside the egg before hatching Humans - very small as the placenta nourishes the embryo.

Sites on birthing http://www.pbs.org/wgbh/nova/miracle/program.html

Sexually Transmitted Diseases
You should know general symptoms and treatments for: HIV and AIDS Chlamydia Hepatitis B Genital Herpes Syphilis Gonorrhea

Causes of Infertility Blocked oviducts
Failure to ovulate Endometriosis Damaged eggs Obstruction of the vas deferens or epididymis Low sperm count Abnormal sperm

Solutions Artificial insemination
Semen is inserted into the uterus by a Dr. Avoids problems such as incorrect positioning of the cervix and uterus. Usually used in combination with in vetro or due to choice as in the case of same sex marriages or infertile partners.

In vetro fertilization
Egg production is enhanced with fertility drugs. Eggs are then surgically removed from the ovaries and mixed with sperm in petri dish. The fertilized eggs (zygotes) are then grown for a few days and the embryos are placed in the uterus for implanting. Progesterone is given to increase the viability of the implant.

In vetro maturation Oocytes mature outside the body prior to IVF.
No (or at least a lower dose of) gonadotropins have to be injected in the body. Cheaper and some react to these drugs. Woman with many follicles are candidates.

Surrogate mother Another woman would carry the fetus to term for you.
This can be used with the persons own eggs and partner’s sperm or donors of each or both.

Super Ovulation This is a process of using fertility drugs to cause many follicles to mature. It is often used in conjunction with other means to induce pregnancy.

Cryo-preservation The freezing of eggs or sperm for use later.
An example would be a young person with cancer that must undergo extensive chemo and radiation treatment may have there gametes preserved for later use.

Birth control Complete the following assignment: Write a brief description of each of the following including the success rate. Abstinence The pill Norplant Morning after Depro-Provera IUD Tubal Ligation Spermacides Diaphgram Condom Vasectomy

IDENTICAL MULTIPLES The formation of IDENTICAL TWINS/TRIPLELTS (babies with the same DNA) occurs early in the morula or blastocyst stage of development.

FRATERNAL (DIZYGOTIC) MULTIPLES
TWO OR MORE EGGS ARE FERTILIZED BY TWO OR MORE INDEPENDENT SPERM. FETUSES ARE SIBLINGS BORN AT THE SAME TIME. THEY CAN BE DIFFERENT OR SAME SEX, RACE, ETC.

FAMOUS FRATERNAL TWINS
ALTHOUGH THEY LOOK A LOT ALIKE THEY ARE JUST SISTERS BORN AT THE SAME TIME.

Teratogens Any agent that causes a structural abnormality in a fetus during pregnancy. It includes but not limited to: Cigarette smoke Alcohol Prescription drugs (we will discuss thalidomide)

Cigarette smoke (including second hand smoke)
Constrict the fetal blood vessels reducing oxygen supply to developing cells Low birth weight and 3x more likely to have neurological-based developmental handicaps. Carcinogens can cross the placental boundary or be transmitted in breast milk.

Cigarette smoke (including second hand smoke)
Increased risk of mis-carriage Increased risk of birthing complications Increased risk of SIDS (Sudden Infant Death Syndrome) Increased risk of asthma and other respiratory issues.

Alcohol Alcohol crosses the placental boundary into the fetus and can damage the developing central nervous system and brain as well as the physical development of other body parts. It can cause behavioral changes such as aggression as well as mental retardation of the child.

Alcohol It causes FAS/FAE (fetal alcohol syndrome or fetal alcohol effects) This causes learning disabilities, hyperactivity, attention disorders, inability to manage anger, poop judgement, and difficulties solving problems. It can also cause low birth weight, small head size, and facial deformaties.

Thalidomide This is a drug that was used many years ago to ease morning sickness. It was later discovered that this drug was causing deformities in babies born to moms that had taken the drug. Of course the severity of any defect is dependent on the amount of drug taken, how often, and at what point in fetal development.

Thalidomide Thalidomide specifically affects bone and limb development and children can be born without limbs or with shortened limbs. It can also cause heart defects and renal (kidney) problems.

Thalidomide

BIRTHING PROCESS OCCURS IN THREE STAGES: DILATION EXPULSION PLACENTAL

DILATION As the baby's head drops down into the pelvis, it pushes against the cervix and causes the cervix to relax and thin out, or efface. When the cervix effaces, the mucus plug is loosened and passes out of the vagina. The mucus may be tinged with blood. This passage of the mucus plug is called "show" or "bloody show." You may or may not notice when the mucus plug passes.

After the cervix begins to efface, it will also begin to open (dilatation). Cervical dilatation is expressed in centimeters from 0 to 10. Zero means that the cervix is closed, and 10 means that it is completely dilated. You will be ready to push when you are 10 centimeters.

Expulsion Stage two of your labor is from full dilation (10 centimeters) until the baby is fully out of the birth canal This stage normally lasts between ten minutes to two hours. There will be a strong urge to bear down or push with the contractions and rest between contractions. Contractions will be 2 to 5 minutes apart and will last for 60 to 90 seconds. Crowning occurs when the baby's head can be seen at the vaginal opening. Pressure and pain will be felt in the birth canal and vaginal opening.

PLACENTAL STAGE The third stage occurs after delivery of the baby.
The placenta and fetal membranes are delivered. The uterus continues to contract to aid in the closing of the blood supply to the now gone placenta.

Monitoring techniques
Ultrasound- an image is produced on a screen by bouncing sound waves off the fetus. -It can detect physical abnormalities. -Find the sex of the fetus. -Locate the position of the fetus.

Amniocentesis A process of extracting some amniotic fluid for DNA testing. This is done with a large needle through the abdomen between weeks.

Fetoscopy A scope is inserted through the abdomen with the aid of an ultrasound and the fetus can be observed for abnormalities. Fetal surgeries can be performed. Actual blood samples can be taken from the umbilical cord.

Chorionic Villus Sampling (CVS)
Very much like amniocentesis but a sample of the chorion is taken instead. This can also be used to detect genetic disorders but can be done earlier in the pregnancy. (10-12 wks) and with less risk of mis-carriage.

Chorionic Villus Sampling (CVS)

PLANT REPRODUCTION Alteration of generations p. 166
The life cycle of plants have 2 generations (haploid and diploid). All the vascular plants (angiosperms, ferns, and gymnosperms) are sporophyte (2n) in adulthood. Non-vascular plants (bryophytes) are gametophyte (n) in adulthood form.

PLANT REPRODUCTION Dioecious or perfect flowers have both female and male parts on the one flower. Monoecious or imperfect flowers have male or female parts. Note: both types of plants use sexual reproduction not self-pollination as the choice of reproductive method. Why????

Monoecious-note the differences ex: squash, bakeapple, corn

Dioecious— note the stamen(male) and carpel (female)

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Sexual Reproduction in plants

Pollen grains contain two or three cells that are the male gametophyte. Pollen grains are produced by meiosis of microspore mother cells that are located along the inner edge of the anther sacs. The tube cell or tube nucleus develops into the pollen tube. The germ cell divides by mitosis to produce two sperm cells.

Pistil The pistil consists of the stigma, style, and ovary containing one or more ovules. These three structures are often termed a pistil or carpel. In many plants, the pistils will fuse for all or part of their length. The Stigma and Style The stigma functions as a receptive surface on which pollen lands and germinates its pollen tube. Corn silk is part stigma, part style. The style serves to move the stigma some distance from the ovary. This distance is species specific.

The Ovary The ovary contains one or more ovules, which in turn contain one female gametophyte. Some plants, such as cherry, have only a single ovary which produces two ovules. Only one ovule will develop into a seed. Female gametophytes of flowering plants develop within the ovule (megaspore) contained within an ovary There are usually eight (haploid) cells in the female gametophyte: a) one egg, two synergids flanking the egg (located at the micropyle end of the embryo sac); b) two polar nuclei in the center of the embryo sac; and three antipodal cells (at the opposite end of the embryo sac from the egg).

Pollination The transfer of pollen from the anther to the female stigma is termed pollination. This is accomplished by a variety of methods which include insects, wind, birds, bats, water, and humans. Some flowers develop in such a way as to pollinate themselves. When the pollen grain lands on the stigma it grows a pollen tube to carry the sperm cells to the egg cells. The pollen tube grows through the stigma and style toward the ovules in the ovary. The germ cell in the pollen grain divides and releases two sperm cells which move down the pollen tube toward the embryo sac.

Pollination One sperm cell fuses with the egg, producing the zygote which will later develop into the next-generation plant. The second sperm fuses with the two polar bodies located in the center of the sac, producing the nutritive triploid endosperm tissue that will provide energy for the embryo's growth and development. This is called double fertilization. The zygote develops into an embryo; the integuments develop into a seedcoat; the ovary develops into a fruit; and the primary endosperm nucleus divides to form endosperm which provides nutrients for the developing embryo and during seed germination.

Vocabulary anther The pollen bearing portion of a stamen in flowering plants. egg A female gamete. embryo sac The female gametophyte of a flowering plant, inside the ovule. endosperm In plants a triploid tissue containing stored food, develops from the union of a sperm nucleus and two nuclei of the central cell of the female gametophyte. Found only in angiosperms. filament in flowers it is the stalk of a stamen. fruit In angiosperms a matured, ripened ovary or group of ovaries and associated structure. Contains the seeds. gametophyte The haploid (n) gamete producing plants have alternating haploid and diploid generations. nucleus In our discussion, the membrane bound structure characteristic of eukaroyotic cells that contains the genetic information in the form of DNA organized into chromosomes. ovary In flowering plants the enlarged basal portion of a carpel or fused carpel containing the ovule or ovules. Ovary matures to become the fruit.

Vocabulary ovules In seed plants a structure composed of a protective outer coat, a tissue specialised for food storage, and a female gametophyte with an egg cell. Becomes a seed after it is fertilized. pistil the stigma, style and, ovary together. pollen In seed plants, spore consisting of an immature male gametophyte and a protective outer covering. seed A complex structure formed by the maturation of the ovule of seed plants following fertilization; upon germination a seed develops into a plant. Seed is made up of a seed coat, embryo and a food reserve. stamens The male structure of a flower which produces pollen. stigma In plants, the region of a carpel serving as a receptive surface for pollen. style In angiosperms, the stalk of a carpel which the pollen tube grows through. zygote The diploid (2n) cell resulting from the union of male and female gametes (fertilization).

Asexual Reproduction Asexual reproduction is the formation of new individuals from the cell (s) of a single parent. It is very common in plants; less so in animals. Some species, such as many orchids, are more frequently propagated vegetatively rather than via seeds. Several methods of asexual reproduction are used by plants and animals. We will be looking at budding, fragmentation, binary fission, asexual spores, and parthenogenesis.

BUDDING Offspring develop as a growth on the body of the parent.
In some species like jellyfish the buds break away and take up an independent existence. In others like corals, the buds remain attached to the parent and the process results in colonies of animals. Budding is also common among parasitic animals like tapeworms.

Fragmentation Where a new organism grows from a fragment of the parent. Each fragment develops into a mature, fully grown individual. Fragmentation is seen in many organisms such annelid worms, sea stars, fungi, and plants.

Binary Fission Asexual reproduction by a separation of the body into two new bodies much like cell division.

Parthenogenesis In parthenogenesis ("virgin birth"), the females produce eggs, but these develop into young without ever being fertilized. Parthenogenesis occurs in some fishes, several kinds of insects, and a few species of lizards.

Asexual spores The most common form of asexual reproduction is by the production of thousands of spores that are clones of one parent. Many fungi use this reproductive method.

Human Reproduction.

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