Chapter 46 Animal Reproduction

1. Chapter 46 Animal Reproduction • Asexual-All genes from one parent, mitotic cell division • many offspring-little variation • Fission • Budding • Gemmules • Fragmentation – Regeneration • Parthenogenesis-between-Daphnia, males of social • insects, some fishes, amphibians, lizards • Sexual-Fusion of haploid gametes to form a zygote; • gametes produced by meiosis; ovum-large sessile; • spermatozoon-small motile; sexual recombination - fewer • offspring - greater variation • Hermaphroditism-most mate, all indv. Are potential • mates; sequential hermaphroditism • External fertilization • Internal fertilization

2. Fission or Budding

3. Parthenogenesis with two females

5. Parthenogenesis with Male stimulation but not fertilization

6. External fertilization

7. Male parental care

8. Hermaphroditism

9. Testes-seminiferous tubules – Leydig cells-produce testosterone scrotum- epididymis- 6m. long tubules; takes 20 days for sperm to pass through; vas deferens-during ejaculation carry sperm up into the abdomen, over the urinary bladder and connect to the urethra inside the prostate gland; semen-secretions of the seminal vesicles (alkaline mucus, fructose, prostaglandins) prostate gland (citrate and anticoagulant) Bulbourethral glands (alkaline fluid that precedes the sperm) and 300 million sperm

10. the penis is composed of three cylinders of spongy erectile tissue that fills with blood pinching off the veins leaving it and the blood pressure causes an erection prepuce or foreskin may be removed by circumcision

11. ovaries contain many follicles (400,000 all formed before a woman is born only 1,000 or so are released-ovulation) that each contain one egg cell (secondary oocyte) corpus luteum- follicular tissue after ovulation continues to secrete estrogen and progesterone; oviducts/Fallopian tubes have funnel–shaped openings the drape the ovaries and cilia pull the egg into it

12. uterus- endometrium- cervix- vagina- hymen-membrane that partially covers the opening to the vagina; labia minora and labia majora-folds of skin tissue around the opening to the vagina; clitoris-erectile tissue similar to the penis

13. Ovary crossection with Several developing follicles Oocyte in a follicle

14. Ovulation

21. GnRH-regulates FSH and LH release from the pituitary FSH-acts on the seminiferous tubules to increase spermatogenesis LH-stimulates Leydig cells to make androgens which stimulate sperm production

22. Estrous cycles occur in all non-primate mammals. Estrus-period just before ovulation and is the only time when most the females of most species will copulate. Due to pheromones and physical changes males know when ovulation occurs. Endometrium is reabsorbed if fertilization does not occur • Menstrual cycle-occurs in humans and other primates; no indications of when ovulation occurs. Menstruation occurs when the endometrium is shed from the uterus through the cervix and vagina.

23. Hypothalamus monitors levels of estrogen and progesterone in blood. It secretes releasing factors (GnRH’s) that cause the pituitary to release LH and FSH. FSH causes a follicle to develop and release estrogen which causes the lining of uterus to thicken. Ovulation triggered by a spurt of LH released by the pituitary. Follicle then becomes the corpus luteum and secretes progesterone

24. fertilization can only occur for 24 hours after ovulation blastocyst implants 7 days after conception and releases human chorionic gonadotropin (HCG)

27. 5 weeks,1cm long 14 weeks, 6cm long 20 weeks, 30cm