Sex and Reproduction

1. 0 Sex and Reproduction

2. 0

3. Sexual and Asexual Reproduction 0 • Sexual reproduction occurs when a new individual is formed through the union of two sex cells (gametes). • produce zygote gametes formed by meiosis in sex organs (gonads). • Asexual reproduction occurs when genetically identical cells are produced from a single parent cell by mitosis. • fission or budding

4. Fertilization and Development 0 • Vertebrate sexual reproduction evolved in the ocean before vertebrates colonized land. • External fertilization - Males generally release sperm into water where the union of the free gametes occurs.

5. Fertilization and Development 0 • Three strategies of Internal fertilization: • Eggs are fertilized internally and deposited outside mother’s body to complete development. • Fertilized eggs are retained within mother to complete development, but all nourishment gained from yolk sac. • Young develop within mother and obtain nourishment directly from mother’s blood.

6. Mammals 0 • Mammals • Females generally undergo reproductive cycles (estrous cycles). (In Heat or Breeding season) • periodic release of mature ovum • Changes in secretion of follicle stimulating hormone (FSH) and luteinizing hormone (LH) by pituitary gland drive cycle. • induced ovulators - Females ovulate only after copulation as a result of LH secretion. • cats and rabbits

7. Male Reproductive System 0 • Sperm are produced in seminiferous tubules. In adult male 100 to 200 million sperm per day • Leydig cells, located in interstitial tissue between seminiferous tubules, secrete testosterone. • Converts indifferent structures into male external genitalia (penis and scrotum). • Secondary sexual characteristics • In an adult, each testis is composed primarily of seminiferous tubules. • testes descend into scrotum • maintains slightly lowered temperature ~ 34oC Leydig Cells

8. Human Male Reproductive System 0

9. Male Reproductive System 0 • Production of sperm • Wall of seminiferous tubule consists of germinal cells which become sperm, by meiosis, and supporting Sertoli cells. • Each parent cell undergoes mitosis, and one of the two daughter cells then undergoes meiosis to form sperm.

10. Testis and Sperm 0

11. Male Reproductive System 0 • Male accessory sex organs • epididymis • vas deferens • seminal vesicles • prostate gland • urethra • erectile tissue

12. B. Vas deferens - 0 • tube where some sperm are stored and connects to the urethra at the base of the urinary bladder vas deferens

13. C. Accessory glands 0 1. Prostate gland- large gland behind urinary bladder and produces seminal fluid. 2. Seminal vesicles- paired glands at bases of vas deferentia and produce seminal fluid. • Seminal fluid serves as a lubricant, pH buffer, and nutrient (high in sugars) seminal vesicle prostate

14. 0 D.Urethra and penis - urethra is tube exiting the urinary bladder and extending the length of the penis, the male intromittent organ. urethra

15. Female Reproductive System 0 • Female embryo develops a clitoris and labia majora. • Ovaries contain ovarian follicles which each contain an egg cell and smaller granulosa cells. • At puberty, estrogen triggers menarche and the formation of secondary sexual characteristics. • breast development, pubic hair

16. Human Female Reproductive System 0

17. Female Reproductive System 0 • Female accessory sex organs • fallopian tubes (oviducts) • uterus • cervix • vagina

18. Female Reproductive System 0 • Menstrual and estrous cycles • At birth, a female’s ovaries contain approximately 2 million follicles. • Some follicles are stimulated to develop each cycle. • Human menstrual cycle lasts approximately one month, and is commonly divided into a follicular phase and a luteal phase.

19. Female Reproductive System 0 • Follicular phase • A few follicles are stimulated to grow under FSH stimulation, but only one achieves full maturity as a tertiary, Graafian, follicle. • Ovulation • Increasing level of estrogen in the blood stimulates the anterior pituitary gland to secrete LH about midcycle. • follicle bursts releasing secondary oocyte

20. Journey of an Egg 0

21. Female Reproductive System 0 - phase1 second half of menstrual cycle • Corpus luteum secretes estrogen and progesterone. - phase2 of the endometrium • Endometrium becomes more vascular, glandular, and enriched with glycogen. • secretory phase

22. Female Reproductive System 0 • In absence of fertilization, corpus luteum triggers its own atrophy toward the end of the luteal phase. • menstrual phase

23. 0

24. LH FSH 2 4 6 8 10 12 14 16 18 20 22 24 26 28 Follicular Phase Luteal Phase Estrogen Progesterone 2 4 6 8 10 12 14 16 18 20 22 24 26 28 VII. The Menstrual Cycle 0 A. Days 1 - 14 1. Uterine activity a. 1-4 - menstrual phase b. 5-7 - repair phase c. 7-14 - proliferative phase - walls of uterus increase as a result of build-up of tissue and blood vessels - Preparation to receive fertilized egg for implantation into wall of uterus

25. LH FSH 2 4 6 8 10 12 14 16 18 20 22 24 26 28 Follicular Phase Luteal Phase Estrogen Progesterone 2 4 6 8 10 12 14 16 18 20 22 24 26 28 The Menstrual Cycle 0 2. Ovarian activity - Graffianfollicle begins to develop during this 14-day period OVULATION OCCURS ON OR ABOUT DAY 14 - Slight increase in body temperature and increase flow of mucus

26. LH FSH 2 4 6 8 10 12 14 16 18 20 22 24 26 28 Follicular Phase Luteal Phase Estrogen Progesterone 2 4 6 8 10 12 14 16 18 20 22 24 26 28 3. Hormones - 0 a. Estrogen gradually increases - Prompts build-up of uterine walls; stimulates pituitary to produce FSH - follicle stimulating hormone - follicular development b. Progesterone - gradually increases to prepare uterus for pregnancy.

27. LH FSH 2 4 6 8 10 12 14 16 18 20 22 24 26 28 Follicular Phase Luteal Phase Estrogen Progesterone 2 4 6 8 10 12 14 16 18 20 22 24 26 28 Menstrual Cycle (cont.) 0 B. Days 14 -20 1. Uterine activity Walls of uterus continue to proliferate (build up) under influence of progesterone

28. LH FSH 2 4 6 8 10 12 14 16 18 20 22 24 26 28 Follicular Phase Luteal Phase Estrogen Progesterone 2 4 6 8 10 12 14 16 18 20 22 24 26 28 Menstrual Cycle (cont.) 0 Days 14-20 2. Ovarian activity -old Graffian follicle becomes corpus luteum and secretes a hormone, LH (luteinizing hormone) which keeps levels of progesterone high.

29. LH FSH 2 4 6 8 10 12 14 16 18 20 22 24 26 28 Follicular Phase Luteal Phase Estrogen Progesterone 2 4 6 8 10 12 14 16 18 20 22 24 26 28 3. Hormones - days 14-20 0 a. estrogen - decreases b. progesterone - highest levels to maintain walls of uterus and blocks FSH c. luteinizing hormone (LH) from ovarian follicle high and maintains levels of progesterone

30. LH FSH 2 4 6 8 10 12 14 16 18 20 22 24 26 28 Follicular Phase Luteal Phase Estrogen Progesterone 2 4 6 8 10 12 14 16 18 20 22 24 26 28 C. Days 20 - 28 0 1. Uterine Activity - continued increase in proliferation until day 28 2. Ovarian activity - continued secretion of LH - to maintain high levels of progesterone - to maintain walls of uterus

31. LH FSH 2 4 6 8 10 12 14 16 18 20 22 24 26 28 Follicular Phase Luteal Phase Estrogen Progesterone 2 4 6 8 10 12 14 16 18 20 22 24 26 28 C. Days 20 - 28 0 3. Hormones a. progesterone begins to decrease if pregnancy has not occurred. b. LH decreases as old corpus luteum loses secretory function • Walls of uterus sloughed away as tissue and blood

32. Birth Control 0 • abstinence • sperm blockage • condom • cervical cap • sperm destruction • jellies or foams • prevention of ovulation • oral contraceptives

33. Birth Control 0 • Prevention of embryo implantation • intrauterine devices (IUD) • morning after pill • Sterilization • vasectomy • tubal ligation

34. Sex Determination in Mammals 0