1. Chapter 40 HUMAN REPRODUCTION AND DEVELOPMENT

2. A. Male Reproductive System Consists of testes, a network of tubules & glandular secretions. Testis Scrotum ] Testes (  gonads) Located outside body cavity in scrotum. Testes contain seminiferous tubules (highly coiled tubules within which sperm are produced). When does sperm production begin? end?

3. ] Epididymis Highly coiled tube in which sperm mature & are stored until ejaculation. Testis Epididymis Vas deferens ] Vas deferens Tube that transports sperm from epididymis into body cavity. Each vas deferens loops over urinary bladder & joins to the urethra. Urethra

4. ] Urethra Tube extending from urinary bladder through penis. Vas deferens Urethra transports urine & sperm, but not at the same time. Pathway of sperm: testis  epididymis  vas deferens  urethra Urethra Bladder

5. Three sets of glands contribute fluids: ] Seminal vesicles Secrete fluid containing fuctose & prostaglandins into vas deferens. Seminal vesicle Prostate gland Bulbourethral gland ] Bulbourethral glands Secrete an alkaline mucus into urethra. ] Prostate gland Surrounds urethra at point where vasa deferentia enter; secretes milky, alkaline fluid into urethra.

6. During sexual arousal, penis becomes erect and semen is ejaculated. Semen consists of: ] Sperm (100-500 million) ] Fluid from seminal vesicles, prostate & bulbourethral glands.

7. B. Female Reproductive System Consists of ovaries, fallopian tubes, uterus & vagina. Ovary Fallopian tube Uterus Vagina ] Ovaries (  gonads) Each ovary contains ~ 1 million follicles at birth. Follicle = developing egg (oocyte) + follicle cells. When does ovulation/menstruation begin? end?

8. Ovary Fallopian tube Uterus Vagina ] Fallopian tubes (oviducts) Tubes that transport oocyte from ovaries to uterus. Site of fertilization. ] Uterus (womb) Muscular sac that functions to receive, retain & nourish a developing embryo. Lower end of uterus (cervix) opens into vagina. ] Vagina (birth canal) Cervix

9. Cyclic Changes in the Ovary & Uterus Regulated by hormones. ] GnRH - produced by hypothalamus; regulates release of FSH & LH from anterior pituitary. ] FSH - produced by anterior pituitary; stimulates development of follicles. ] LH - produced by anterior pituitary; triggers ovulation & formation of corpus luteum.

10. ] Estrogen - produced by follicle cells & corpus luteum; causes endometrium (uterine lining) to thicken. ] Progesterone - produced by corpus luteum of ovary; increases thickness of endometrium. Ovarian & menstrual cycles occur about every 28 days (puberty  menopause).

11. Day 1 of cycle: low levels of estrogen, progesterone, FSH & LH signal hypothalamus...

12. C. Prenatal Development (gestation) Typically divided into 3 stages: ] Preembryonic stage (first 2 weeks) Includes fertilization, cleavage, implantation & beginning of gastrulation. ] Embryonic stage (3rd - 8th weeks) Completion of gastrulation & organogenesis. ] Fetal period (9th week - birth) Organs begin to function & coordinate to form organ systems.

13. 1. Fertilization Union of a sperm and “egg”, forming a zygote. Female ovulates a secondary oocyte (arrested in metaphase II). Oocyte begins journey down fallopian tube; must be fertilized within 12-24 hours.

14. Male deposits sperm in female vagina. Sperm are capacitated (develop fertilizing ability) as they swim toward oocyte. Acrosomal enzymes of sperm digest outer coverings of oocyte. Only 1 sperm enters! Sperm entry signals secondary oocyte to complete meiosis II.

15. 2. Cleavage Period of rapid cell division following fertilization. ] Blastomeres - daughter cells ] Morula - solid ball of ~ 16 cells ] Blastocyst - fluid-filled sphere (~100 cells)

16. 3. Implantation Nestling of blastocyst into endometrium. Blastocyst (5 days post- fertilization) trophoblast inner cell mass blastocyst cavity Trophoblast forms chorion. Trophoblast/chorion produces hCG (human chorionic gonadotropin) hCG prevents degeneration of corpus luteum

17. 4. Gastrulation Process that forms the 3 primary germ layers (ectoderm, mesoderm & endoderm ) ; blastocyst is now a gastrula. 9-day implanted blastocyst amniotic cavity yolk sac epiblast hypoblast embryonic disc chorion 16-day embryo (gastrula) cut edge of amnion epiblast Notochord forms beneath primitive streak.

18. Derivatives of the primary germ layers: ] Ectoderm - nervous system, sense organs, epidermis of skin, hair, nails, sweat glands & oil glands. ] Endoderm - organs & lining of digestive & respiratory systems. ] Mesoderm - notochord, dermis of skin, bones, muscles, circulatory system, urinary system & reproductive system.

19. Roles of Extraembryonic Membranes ] Chorion - forms the fetal portion of the placenta. Placenta functions in exchange of materials, and produces estrogen & progesterone. ] Amnion - protects developing embryo. ] Yolk sac - produces blood cells until 6th week; develops into intestines & germ cells. ] Allantois - forms as outpocketing of yolk sac; forms umbilical cord & becomes part of urinary bladder.

21. 5. Organogenesis Formation of body organs & organ systems. First major event in organogenesis is neurulation (formation of the neural tube). ] Notochord induces overlying ectoderm to form neural groove.

23. Sex Determination Sex is determined at fertilization: ] XY embryos develop into males (SRY gene is activated in week 7). ] XX embryos develop into females

24. Digestive & respiratory systems are last to mature. 6. Labor and Birth Occurs ~266 days post-fertilization (280 days from last menstrual period). ] Stage 1: dilation stage (6-12 hrs) Initiated by oxytocin, which stimulates: F uterus to contract F placenta to produce prostaglandins Descent of fetus ruptures amniotic sac & dilates cervix to 10 centimeters.

25. ] Stage 2: delivery of infant (~2 hrs) Lasts from full dilation to birth. Usually delivered in head-first orientation. Cesarean section - surgical delivery. ] Stage 3: delivery of placenta (~30 min) Uterine contractions expel placenta & extraembryonic membranes. Of every 100 secondary oocytes exposed to sperm, only 31 will survive to be born.

26. D. Postnatal Development