1. 1 Sex and Reproduction Chapter 50

2. 2 Sexual and Asexual Reproduction Sexual reproduction occurs when a new individual is formed through the union of two sex cells (gametes). – produce zygote – Haploid 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

3. 3 Reproduction Parthogenesis hermaphroditism - both sex organs

4. 4 Fertilization and Development External fertilization - Males generally release sperm into water where the union of the free gametes occurs. Internal Fertilization - most cartilaginous fish, reptiles, birds, mammals.

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

6. 6 Mammals – Females generally undergo reproductive cycles (estrous cycles).  periodic release of mature ovum  Changes in secretion of follicle stimulating hormone (FSH) and luteinizing hormone (LH) by pituitary gland drive cycle. – induced ovulators -cats and rabbits

7. 7 Mammals Monotremes are oviparous. – most primitive mammals Marsupials give birth to incompletely developed fetuses. Placental mammals retain young for a long period of development within the mother’s uterus.

8. 8 Human Male Reproductive System

9. 9 Testis and Spermatogenesis

10. 10 Male Reproductive System Spermatozoa – Head encloses nucleus and capped by an acrosome - contains enzymes that aid in egg penetration.  body and tail provide propulsion

11. 11 Male Reproductive System Hormonal control of male reproduction – FSH stimulates the Sertoli to facilitate sperm development. – LH stimulates Leydig cells to secrete testosterone.  Principle negative feedback inhibition applies to FSH and LF secretion.

12. 12 Human Female Reproductive System

13. 13 Female Reproductive System Female accessory sex organs – fallopian tubes (oviducts) – uterus  endometrium – cervix – vagina

14. 14 Female Reproductive System Proliferative phase of the endometrium Luteal phase secretory phase – Corpus luteum secretes estrogen and progesterone. – In absence of fertilization, corpus luteum triggers its own atrophy toward the end of the luteal phase. menstrual phase - menses

15. 15 Journey of an Egg