Asexual reproduction one parent Sexual reproduction fusion of male gametes (sperm) and female gametes (eggs)

Asexual Reproduction Fission separation of a parent into two or more individuals of about the same size Budding two new individuals arise from outgrowths of existing ones Fragmentation breaking of the body into pieces, some or all of which develop into adults must be accompanied by regeneration, regrowth of lost body parts

Reproductive Cycles and Patterns cycles related to changing seasons controlled by hormones and environmental cues reproduce asexually or sexually, or they may alternate these methods

Estrogen Ovulation Female- like Progesterone Ovary size Time Hormone level Ovulation Behavior Male- like Female- like Male- like

Hermaphroditism each individual has male and female reproductive systems sequential hermaphroditism reverses its sex during its lifetime

Fertilization external fertilization eggs shed by the female are fertilized by sperm in the external environment

Eggs

internal fertilization sperm are deposited in or near the female reproductive tract fertilization occurs within the tract Requires behavioral interactions & compatible copulatory organs Fertilization requires: critical timing environmental cues Pheromones courtship behavior

Ensuring the Survival of Offspring produce more offspring than the environment can handle proportion that survives is quite small (usually) Adaptations of terrestrial organisms: eggs can withstand harsh environments retain the embryo Develops within female parental care

Male honeybee (drone) Seminal vesicle Vas deferens Testis Accessory gland Ejaculatory duct Penis Female honeybee (queen) Accessory gland Ovary Oviduct Vagina Spermatheca

Female Reproductive Anatomy External Anatomy Labia Clitoris Internal Anatomy Ovaries Fallopian tubes (oviduct) Uterus Vagina Animation: Female Reproductive Anatomy Animation: Female Reproductive Anatomy

Bartholin’s gland Vaginal opening Vagina Cervix (Rectum) Oviduct Ovary Uterus (Urinary bladder) (Pubic bone) Urethra Shaft Glans Prepuce Labia majora Clitoris Labia minora

Vagina Cervix Oviduct Ovaries Uterus Endometrium Follicles Corpus luteum Uterine wall

Male Reproductive Anatomy External Scrotum Penis Internal Gonads produce sperm and hormones accessory glands Animation: Male Reproductive Anatomy Animation: Male Reproductive Anatomy

Seminal vesicle Urethra Scrotum Glans penis Testis Prostate gland Bulbourethral gland Erectile tissue of penis Epididymis (Urinary bladder) (Public bone) Prepuce Vas deferens Ejaculatory duct (Rectum)

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

Gametogenesis Oogenesis development of mature ova Spermatogenesis production of mature sperm

Primary germ cell in embryo Mitotic division Primary oocyte Ovary Oogonium Differentiation Oogonium in ovary Primary oocyte within follicle Growing follicle Secondary oocyte Completion of meiosis I and onset of meiosis II Ovulation First polar body Mature follicle Entry of sperm triggers completion of meiosis II Second polar body Ovum Ruptured follicle Ovulated secondary oocyte Corpus luteum Degen- erating corpus luteum

Spermatogonium Primary spermatocyte (in prophase of meiosis I) Mitotic division, producing large numbers of spermatogonia Meiosis I completed Differentiation and onset of meiosis I Secondary spermatocyte Meiosis II Early spermatids Spermatids (at two stages of differentiation) Differentiation Sperm cells Neck Head Midpiece Tail Plasma membrane Mitochondria AcrosomeNucleus Sertoli cell nucleus Lumen of Seminiferous tubule Cross section of seminiferous tubule Testis Epididymis Seminiferous tubule

Oogenesis differs from spermatogenesis in three major ways: cytokinesis is unequal almost all of the cytoplasm in one daughter cell, the secondary oocyte Unlike sperm, eggs are not produced continuously throughout life Oogenesis has long “resting” periods, whereas sperm are produced in uninterrupted sequence

In menstrual cycles: endometrium is shed from the uterus menstruation Sexual receptivity is not limited to a timeframe In estrous cycles: endometrium is reabsorbed by the uterus Sexual receptivity is limited to a “heat” period

The Human Female Reproductive Cycle Five kinds of hormones scheme involving positive and negative feedback Animation: Post Ovulation Animation: Post Ovulation Animation: Ovulation Animation: Ovulation

Hypothalamus Anterior pituitary Control by hypothalamus Pituitary gonadotropins in blood FSHLH FSH LH GnRH Inhibited by combination of estrogen and progesterone Inhibited by low levels of estrogen Stimulated by high levels of estrogen LH surge triggers ovulation FSH and LH stimulate follicle to grow Mature follicle Growing follicle Ovarian cycle Corpus luteum Degenerating corpus luteum Follicular phase OvulationLuteal phase Progesterone and estrogen secreted by corpus luteum Estrogen secreted by growing follicle in increasing amounts Progesterone and estro- gen promote thickening of endometrium Peak causes LH surge Ovarian hormones in blood Estrogen level very low Progesterone Estrogen Endometrium Uterine (menstrual) cycle Menstrual flow phaseProliferative phaseSecretory phase Days

Human Female Reproductive Cycle ovarian cycle follicle growth Ovulation Uterine (menstrual) cycle Occurs if implantation has not occurred Menopause Occurs after about 450 menstrual cycles Cessation of ovulation and menstruation

Hormonal Control of the Male Reproductive System Androgens Testosterone and others responsible for the primary and secondary sex characteristics of the male Androgen secretion and sperm production are controlled by hypothalamic and pituitary hormones Animation: Male Hormones Animation: Male Hormones

Conception, Embryonic Development, and Birth Conception fertilization of an egg by a sperm occurs in oviduct Cleavage develops into a blastocyst Implantation in the endometrium Pregnancy (gestation) carrying one or more embryos in the uterus Duration correlates with: body size of young at birth maturity of young at birth

From ovulation to implantation Cleavage starts Fertilization occurs Uterus Ovulation Ovary Endometrium The blastocyst implants Cleavage continues

Implantation of blastocyst Blastocyst Endo- metrium Cavity Inner cell mass Trophoblast

Human Development -First Trimester Placenta formation Organogenesis

Umbilical cord Chorionic villus containing fetal capillaries Maternal blood pools Uterus Placenta Maternal arteries Maternal veins Maternal portion of placenta Fetal portion of placenta (chorion) Umbilical arteries Umbilical vein Umbilical cord Fetal arteriole Fetal venule

5 weeks.14 weeks. 20 weeks.

Second Trimester Fetal growth Fetal activity The mother may feel fetal movements uterus growth pregnancy to become obvious

Third Trimester Fetal growth Fills space within the embryonic membranes hormones induces and regulates labor

Estrogen Oxytocin from ovaries from fetus and mother’s posterior pituitary Induces oxytocin receptors on uterus Stimulates uterus to contract Stimulates placenta to make Prostaglandins Stimulate more contractions of uterus Positive feedback

Dilation of the cervix Expulsion: delivery of the infant Placenta Cervix Uterus Umbilical cord Delivery of the placenta Uterus Placenta (detaching) Umbilical cord

Contraception Some general contraceptive methods: Preventing release of eggs and sperm Keeping sperm and egg apart Preventing implantation of an embryo

MaleFemale Method Event Method Vasectomy Production of viable sperm Production of viable oocytes Sperm transport down male duct system Ovulation Sperm deposited in vagina Capture of the oocyte by the oviduct Condom Abstinence Coitus interruptus (very high failure rate) Abstinence Sperm movement through female reproductive tract Transport of oocyte in oviduct Tubal ligation Spermicides; diaphragm; cervical cap; progestin alone (minipill, implant, or injection) Meeting of sperm and oocyte in oviduct Union of sperm and egg Implantation of blastocyst in properly prepared endometrium Morning-after pill (MAP) Progestin alone Birth Combination birth control pill (or injection, patch, or vaginal ring)