Sections 6.6 – 11.4 Reproduction

6.6.1 Draw and label diagrams of the adult male and female reproductive systems Outline the role of hormones in the menstrual cycle, including FHS, LH and estrogen and progesterone Annotate a graph showing hormone levels in the menstrual cycle, illustrating the relationship between changes in hormone levels and ovulation, menstruation and thickening of the endometrium Annotate a diagram of the ovary to show the location and function of germinal epithelium, primary follicles, mature follicle and secondary oocyte Outline the process involved in oogenesis within the ovary, including mitosis, cell growth, the two divisions of meiosis, the unequal division of the cytoplasm and the degeneration of the polar body Female Reproductive System

6.1.1 Draw and label diagrams of the adult male and female reproductive systems.

Figure (Rectum) Cervix Vagina Major vestibular (Bartholin’s) gland Vaginal opening Oviduct Ovary Uterus (Urinary bladder) (Pubic bone) Urethra Body Glans Prepuce Clitoris Labia minora Labia majora Ovaries Oviduct Follicles Corpus luteum Uterine wall Endometrium Vagina Uterus Cervix

Female Reproductive System

Figure 46.10a (Rectum) Cervix Vagina Major vestibular (Bartholin’s) gland Vaginal opening Oviduct Ovary Uterus (Urinary bladder) (Pubic bone) Urethra Body Glans Prepuce Clitoris Labia minora Labia majora

›Pituitary Hormones: –FHS (Follicle Stimulating Hormone) stimulates these changes: ›Development of the oocyte in the follicle (follicle contains the oocyte) ›Thickening of the follicle wall ›Secretion of follicular fluid ›Secretion of estrogen by follicle wall –LH (Leutenizing Hormone) stimulates these changes: ›Completion of meiosis in the oocyte ›Partial digestion of the follicle wall allowing it to burst open (ovulation) ›Growth of the corpus luteum which secretes estrogen and progesterone Outline the role of hormones in the menstrual cycle, including FSH, LH and estrogen and progesterone

›Estrogen- secreted by the developing follicles: –Thickening of endometrium –Blood vessels growth in the endometrium –Increase in FSH receptors in follicle –Inhibition of FSH secretion and stimulation of LH secretion estrogen levels are high ›Progesterone released from the corpus leutium, causes these changes –maintenance of thickening of the endometrium with many blood vessels –Inhibition of FSH and LH

6.6.3 Annotate a graph showing hormone levels in the menstrual cycle, illustrating the relationship between changes in hormonal levels and ovulation, menstruation and thickening of the endometrium

Figure Control by hypothalamus(a) Hypothalamus GnRH Anterior pituitary FSHLH Inhibited by combination of estradiol and progesterone Stimulated by high levels of estradiol Inhibited by low levels of estradiol    (b)Pituitary gonadotropins in blood LH FSH FSH and LH stimulate follicle to grow 6 LH surge triggers ovulation Ovarian cycle Growing follicle Maturing follicle Corpus luteum Degenerating corpus luteum Follicular phaseOvulationLuteal phase Estradiol secreted by growing follicle in increasing amounts (c) Progesterone and estradiol secreted by corpus luteum (d) Ovarian hormones in blood Estradiol Peak causes LH surge (see ) Progesterone Progesterone and estra- diol promote thickening of endometrium Estradiol level very low (e) Uterine (menstrual) cycle Endometrium Menstrual flow phaseProliferative phase Secretory phase Days

Figure 46.13a Control by hypothalamus(a) Hypothalamus GnRH Anterior pituitary FSHLH Inhibited by combination of estradiol and progesterone Stimulated by high levels of estradiol Inhibited by low levels of estradiol    Reproduction begins with release of GnRH which stimulates the anterior pituitary to release FSH and LH 2. FSH and LH Release

Figure 46.13b (b)Pituitary gonadotropins in blood LH FSH FSH and LH stimulate follicle to grow LH surge triggers ovulation Ovarian cycle Growing follicle Maturing follicle Corpus luteum Degenerating corpus luteum Follicular phaseOvulationLuteal phase (c) Days 3678

3. FS stimulates the follicle growth aided by LH 4. the cells of growing follicles begin to make estradiol. 5. when estradiol secretion by the growing follicle begins to rise steeply, 6. the FSH and LH levels increase Low levels of estradiol inhibits the secretion GnRH and High level increase release of GnRH (positive feedback) 7. The maturing follicle, containing a fluid filled cavity, enlarges, forming a bulge near the surface of the ovary. The follicle phase ends with ovulation [about a day after the spike], releasing the secondary oocyte

Figure 46.13b (b)Pituitary gonadotropins in blood LH FSH FSH and LH stimulate follicle to grow LH surge triggers ovulation Ovarian cycle Growing follicle Maturing follicle Corpus luteum Degenerating corpus luteum Follicular phaseOvulationLuteal phase (c) Days 3678

8.Luteal phase: after the release of the oocyte, LH triggers the follicle to the transformed into corpus luteum, a glandular structure. The corpus luteum secreted progesterone and estradiol which leads to negative feedback on the hypothalamus and pituitary – thus preventing the stimulation of another egg Eventually LH and FSH levels drop, GnRH drops and this leads to the degeneration of the corpus luteum Degeneration in the corpus luteum triggers the reduction in estradiol and progesterone which leads to the cycle beginning again –Endometrium is sloughed away (menstruation) –No longer inhibited, FSH can start menstrual cycle again –If fertilization of egg occurs, the zygote releases a hormone (hCG) which maintains the corpus luteum

Figure 46.13c Estradiol secreted by growing follicle in increasing amounts Progesterone and estradiol secreted by corpus luteum (d) Ovarian hormones in blood Estradiol Peak causes LH surge (see ) Progesterone Progesterone and estra- diol promote thickening of endometrium Estradiol level very low (e) Uterine (menstrual) cycle Endometrium Menstrual flow phaseProliferative phase Secretory phase Days (e)

Figure Control by hypothalamus(a) Hypothalamus GnRH Anterior pituitary FSHLH Inhibited by combination of estradiol and progesterone Stimulated by high levels of estradiol Inhibited by low levels of estradiol    (b)Pituitary gonadotropins in blood LH FSH FSH and LH stimulate follicle to grow 6 LH surge triggers ovulation Ovarian cycle Growing follicle Maturing follicle Corpus luteum Degenerating corpus luteum Follicular phaseOvulationLuteal phase Estradiol secreted by growing follicle in increasing amounts (c) Progesterone and estradiol secreted by corpus luteum (d) Ovarian hormones in blood Estradiol Peak causes LH surge (see ) Progesterone Progesterone and estra- diol promote thickening of endometrium Estradiol level very low (e) Uterine (menstrual) cycle Endometrium Menstrual flow phaseProliferative phase Secretory phase Days

›Oogenesis describes the production of female gametes (ova) within the ovary ›The process begins during fetal development, when a large number of cells (oogonia) are formed by mitosis before undergoing a period of growth ›These cells begin meiosis but are arrested in prophase I until puberty ›At puberty, some follicles continue to develop each month is response to FSH secretion ›These follicles complete the first meiotic division to form two cells of unequal size Outline the process involved in oogenesis within the ovary, including mitosis, cell growth, the two divisions of meiosis, the unequal division of the cytoplasm and the degeneration of the polar body

›The cell with less cytoplasm is a polar body (which degenerates), while the larger cell forms a secondary oocyte ›The secondary oocyte begins the second meiotic division but is arrested in prophase II (until fertilization) ›It is released from the ovary (ruptured follicle develops into corpus luteum) and, if fertilization occurs, will complete meiosis ›The second meiotic division will produce an ovum and a second polar body

›Germinal epithelium ›Primary follicles ›Mature follicle ›Secondary ooctye Annotate a diagram of the ovary that show the location and function of:

›The ovary contains follicles in various stages of development ›Egg cells within primordial follicles have been arrested in prophase I and have yet to undergo meiotic division ›Egg cells within mature follicles have begun meiotic division and are released from the ovary as secondary oocytes (arrested in prophase II) ›The ruptured follicle develops into a corpus luteum that will, in time, degenerate into a corpus albicans ›The germline epithelium functions as an epithelial layer separating ovarian tissue from the rest of the body - it is not involved in oocyte development Oogenesis video

6.6.1 Draw and label diagrams of the adult male and female reproductive systems List three roles of testosterone Annotate a light micrograph of the testis tissue to show the location and the function of the interstitial cells (Leydig), germinal epithelium cells, developing spermatozoa Outline the process involved in spermatogenesis within the testis including: mitosis, cell growth, the two divisions of meiosis, and cell differentiation State the role of LH, testosterone and FSH in spermatogenesis Draw and label a diagram of mature sperm and egg Outline the role of the epididymis, seminal vesicles and the prostate gland in the production of semen. Male Reproductive System

Reproduction in Males

Figure 46.11a Seminal vesicle (behind bladder) Urethra Scrotum (Urinary bladder) Prostate gland Bulbourethral gland Erectile tissue of penis Vas deferens Epididymis Testis

Figure 46.11b Seminal vesicle (Rectum) Vas deferens Ejaculatory duct Prostate gland Bulbourethral gland Vas deferens Epididymis Testis Scrotum (Urinary bladder) (Urinary duct) (Pubic bone) Erectile tissue Urethra Glans Prepuce Penis

1.Pre-natal development of male genitalia 2.Development of secondary sex characteristics 3.Maintenance of sex drive (libido) 4.Anabolic activity leads to increase body mass List three roles of testosterone

›Interstitial cells (Leydid cells) - produce the male sex hormone, testosterone ›Germinal epithelium: germ cells, spermatogonia (2n), divides by mitosis to make 1⁰ spermatocytes. –Germ cells will divide by meiosis to make spermatozoa) ›Developing spermatozoa ›Sertoli cells – nourish developing spermatozoa Annotate a light micrograph of the testis tissue to show the location and the function of the

“Germ Cells” Spermatogonoia (2n) mitosis Primary spermatocyte meiosis I Secondary spermatocyte(1n) meiosis II Spermatids Maturation produces spermatozoa (1n gametes) ( million sperm/ejaculation) Sperm production

Testes 40X magnification

A. Spermatocytes B. Spermatogonium C. Provides Nourishment for the developing cell D. produce the male sex hormone, testosterone

›Mitosis ›Cell growth ›Meiosis (both phases) ›Cell differentiation ›Spermatogenesis (5:38)Spermatogenesis Outline the process involved in spermatogenesis within the testis including:

›Spermatogenesis describes the production of spermatozoa (sperm) in the seminiferous tubules of the testes ›The first stage of sperm production requires the division of germline epithelium by mitosis –These cells (spermatogonia) then undergo a period of growth ›This is followed by two meiotic divisions that result in four haploid daughter cells ›These haploid cells then differentiate to form sperm cells ›The developing sperm cells are nourished throughout by the Sertoli cells

State the role of LH, Testosterone and FSH in spermatogenesis ›LH: Stimulates the interstitial cells (Leydig cells) to produce testosterone ›FSH: Stimulates the (first) meiotic division of spermatogonia ›Testosterone: Stimulates the (second) meiotic division of spermatogonia and the maturation of spermatozoa through differentiation

Figure Hypothalamus    GnRH Anterior pituitary FSHLH Sertoli cells Leydig cells InhibinSpermatogenesisTestosterone Testis Negative feedback

Figure 46.12ac Plasma membrane Tail Neck Midpiece Head Mitochondria Nucleus Acrosome Draw and label a diagram of a mature sperm and egg

›Epididymus ›Seminal vesicles ›Prostate gland Outline the role of each in regards to production of semen:

Epididymis ›Testicular fluids are removed, concentrating the sperm ›Sperm mature and develop the ability to swim ›It stores the sperm for 2–3 months. ›Final maturation is completed in the female reproductive tract.female A. Head of epididymis, B. Body of epididymis, C. Tail of epididymis, and D. Vas deferens

Seminal Vesicle ›Adds nutrients (including fructose) for respiration ›Secretes prostaglandins, causing contractions to the female system and helping sperm move towards the egg Prostate Gland ›Secretes alkaline fluid which neutralizes vaginal acids (changes pH from 4 to 6 which aids sperm motility)

Figure 46.12ac Plasma membrane Tail Neck Midpiece Head Mitochondria Nucleus Acrosome

Compare the process of spermatogenesis and oogenesis including the number of gametes and the timing of the formation and release of gamets.

6.6.5 Outline the process of in vitro fertilization (IVF) Discuss the ethical issues associated with IVF Describe the process of fertilization, including the acrosome reaction, penetration of the egg membrane by a sperm and the cortical reaction Outline the role of HCG in early pregnancy Outline early embryo development up to the implantation of the blastocyst Explain how structure and function of the placenta, including its hormonal role in secretion of estrogen and progesterone, maintain pregnancy State that fetus is supported and protected by the amniotic sac and amniotic fluid State that materials are exchanged between the maternal and fetal blood in the placenta Outline the process of birth and its hormonal control, including the changes in progesterone and oxytocin levels and positive feedback. Fertilization

In vitro fertilization refers to fertilization that occurs outside the body ('in vitro' = 'in glass') Stop normal menstrual cycle (with drugs) Hormone treatments to develop follicles (FSH to stimulate follicle growth ; hCG for follicle maturation) Extract multiple eggs from ovaries OUTLINE THE PROCESS OF IN VITRO FERTILIZATION (IVF)

Sperm selected, prepared (capacitation) and then injected into egg via intra- cytoplasmic sperm injection (ICSI) Fertilization occurs under controlled conditions (in vitro) Implantation of multiple embryos into uterus Test for pregnancy is conducted to see if implantation was successful

›IVF is expensive and might not be equally accessible to all ›Success rate is low (~15%) and therefore stressful for couples ›It could lead to eugenics (e.g. gender choice) ›Often leads to multiple pregnancies which may be unwanted, unable to be budgeted for and involves extra birth risks ›Issues concerning storage and disposal of unused embryos (right to life concerns) ›There are cultural and religious objections to embryo creation by such means ›Inherited forms of infertility may be passed on to children DISADVANTAGES ›Chance for infertile couples to have children ›Genetic screening of embryos could decrease suffering from genetic diseases ›Spare embryos can be stored for future pregnancies or used for stem cell research ADVANTAGES Discuss the ethical issues associated with IVF.

›When the sperm enters the female reproductive tract, biochemical changes to the sperm occur in the final part of its maturation (capacitation). ›The sperm is attracted to the egg due to the release of chemical signals from the secondary oocyte (chemotaxis) ›Fertilization generally occurs in the oviduct (fallopian tube) ›To enter the egg membrane, the sperm must penetrate the protective jelly coat (zona pellucida) surrounding the egg via the acrosome reaction –The acrosome vesicle fuses with the jelly coat and releases digestive enzymes which soften the glycoprotein matrix Describe the process of fertilization, including the acrosome reaction, penetration of the egg membrane by a sperm and the cortical reaction.fertilization,

›The membrane of the egg and sperm then fuse and the sperm nucleus (and centriole) enters the egg ›To prevent other sperm from penetrating the fertilized egg (polyspermy), the jelly coat undergoes biochemical changes via the cortical reaction –The cortical granules release enzymes that destroy the sperm-binding proteins on the jelly coat Fertilization video: 5:42

›Now fertilized, the nucleus of the secondary oocyte completes meiosis II and then the egg and sperm nuclei fuse to form a diploid zygote

Outline the role of HCG in early pregnancy ›The endometrium is a blood-rich environment in which an implanted zygote can grow and it is sustained by the hormone progesterone ›If progesterone levels aren't maintained (i.e. the corpus luteum degenerates), then the endometrium will be sloughed away (menstruation) ›A fertilized zygote develops into a blastocyst that secretes human chorionic gonadotrophin (hCG) ›hCG maintains the corpus luteum post-ovulation so that the blastocyst can remain embedded in the endometrium and continue to develop ›Gradually the placenta develops and produces progesterone (at around weeks), at which point the corpus luteum is no longer needed

›After fertilization, the zygote undergoes several mitotic divisions to create a solid ball of cells called a morula (at around 4 days) ›Unequal divisions beyond this stage cause a fluid-filled cavity to form in the middle - this makes a blastocyst (at around 5 days) ›The blastocyst consists of: –An inner mass of cells (this will develop into the embryo) –An outer layer called the trophoblast (this will develop into the placenta) –A fluid filled cavity (called the blastocoele) ›These developments all occur as the developing embryo is moving from the oviduct to the uterus ›When the blastocyst reaches the uterus, it will embed in the endometrium (implantation) Outline early embryo development up to the implantation of the blastocyst.

›Structure and Function: –The placenta is a disc-shaped structure that nourishes the developing embryo –It is formed from the development of the trophoblast upon implantation and eventually invades the uterine wall –The umbilical cord connects the fetus to the placenta and maternal blood pools via open ended arterioles into intervillous spaces (lacunae) Explain how structure and function of the placenta, including its hormonal role in secretion of estrogen and progesterone, maintain pregnancy.

–Chorionic villi extend into these spaces and facilitate the exchange of materials between the maternal blood and fetal capillaries –Nutrients, oxygen and antibodies will be taken up by the fetus, while carbon dioxide and waste products will be removed –The placenta is expelled from the uterus after childbirth

Hormonal Role ›The placenta also takes over the hormonal role of the ovary (at around 12 weeks) ›Estrogen stimulates growth of the muscles of the uterus (myometrium) and the development of the mammary glands ›Progesterone maintains the endometrium, as well as reduces uterine contractions and maternal immune response (no antibodies against fetus) ›Both estrogen and progesterone levels drop near time of birth

›The fetus develops in a fluid-filled space called the amniotic sac ›Amniotic fluid is largely incompressible and good at absorbing pressure, and so protects the child from impacts to the uterine wall ›The fluid also creates buoyancy so that the fetus does not have to support its own body weight while the skeletal system develops ›Finally, amniotic fluid prevents dehydration of the tissues, while the amniotic sac provides an effective barrier against infection State that fetus is supported and protected by the amniotic sac and amniotic fluid

›The fetus relies on the exchange of materials across the placental wall to grow and develop: State that materials are exchanged between the maternal and fetal blood in the placenta

›The process of childbirth is called parturition and is controlled by the hormone oxytocin ›After nine months, the fetus is fully grown and takes up all available space in the uterus, stretching the walls of the uterus ›This causes a signal to be sent to the brain, releasing oxytocin from the posterior pituitary Outline the process of birth and its hormonal control, including the changes in progesterone and oxytocin levels and positive feedback.

›Oxytocin inhibits progesterone, which was inhibiting uterine contractions ›Oxytocin also directly stimulates the smooth muscle of the uterine wall to contract, initiating the birthing process ›The contraction of the uterine wall causes further stretching, which triggers more oxytocin to be released (causing even more contraction)

›Additionally, the fetus responds to the cramped conditions by releasing prostaglandins which cause further myometrial contractions ›As the stimulus causing oxytocin release is increased by the effects of oxytocin, this creates a positive feedback pathway ›Contractions will stop when labor is complete and the baby is birthed (no more stretching of the uterine wall)

Happy Birthday!