1. Animal Reproduction Chapter 46
Rick L. Knowles
Liberty Senior High School
A.P. Biology

2. Concept 46.1: Both asexual and sexual reproduction occur in the animal kingdom.
Asexual reproduction – “without sex” all genes come from one parent; derived by mitosis.
Sexual reproduction – fusion of haploid gametes to form zygote; derived from meiosis.

3. Types of Asexual Reproduction
Fission – separation of parent into equal sizes (sea anemone, Fig. 46.2).
Budding - outgrowths of existing organisms (corals, hydra).
Fragmentation – breaking the body into several pieces that can develop into complete adults (starfish).

4. Fission in Sea Anemones
Figure 46.2

5. Reproductive Cycles and Patterns
Most animals have cycles of reproductive activity – seasons favorable to survival of offspring.
Periodic reproduction saves energy.
Regulated by hormones and/or env. cues.
Animals may either be asexual, sexual or both.

6. Special Type of Asexual Reproduction
Parthenogenesis – an unfertilized egg (1 n) undergoes mitosis w/o cytokinesis (male bees, several fish, reptiles).
May be an alternative to sexual reproduction.

7. Can haploid cells develop into functioning animals or plants?
Bees Do It!

8. How to make a bee colony? Fertilized Egg, (2n) Female Worker, (2n)
Meiosis
Mitosis w/o Cytokinesis
Unfertilized Egg, (1n)
Queen, (2n)
Male Drone, (1n)

9. Strawberry Plants do both Asexual and Sexual Reproduction
Sexual Flowers
Asexual Stolon

10. Whiptails Reproduce Exclusively by Parthenogensis
(a) Both lizards in this photograph are C. uniparens females. The one on top is playing the role of a male. Every two or three weeks during the breeding season, individuals switch sex roles.
(b) The sexual behavior of C. uniparens is correlated with the cycle of ovulation mediated by sex hormones. As blood levels of estrogen rise, the ovaries grow, and the lizard behaves like a female. After ovulation, the estrogen level drops abruptly, and the progesterone level rises; these hormone levels correlate with male behavior.
Figure 46.3a, b

11. Sexual Reproduction in Sessile Animals
If you’re lonely, you better be flexible!
Hermaphroditism – each individual has male and female reprod. systems; each produce sperm and ova.
Figure 46.1 – Mating Earthworms

12. Sequential Hermaphroditism
Individual may reverse its sex during its lifetime; may be female-first or male-first.
Figure 46.4: Caribbean bluehead wrasse – all born female, but the largest becomes male within a week.
Show Me! Bizarre Breeding, video #132

13. External Fertilization
Eggs are released into water by female where they are fertilized by the male.
Egg release triggered by hormones, env. conditions, male behavior.
Figure 46.5
Eggs

14. Internal Fertilization
Sperm deposited in or near the female reproductive tract.
An adaptation to terrestrial life.
Requires cooperative behavior (for mating) and development of copulatory organs.

15. Fig. 46.9

16. Fig. 46.9

17. Several (Primary) Follicles in Ovary

18. Mature (Graafian) Follicle
Fluid-filled Cavity
Secondary Oocyte
Follicle (Granulosa) Cells

19. Female Reproductive Tract
Ovaries – female gonads; in pelvic cavity and flank the uterus; held by mesentery.
Follicle – consists of one egg cell and many layers of follicle (granulosa) cells – produce estrogen and progesterone.
Ovulation – secondary oocyte and follicle cells rupture from the ovary.
Corpus Luteum – remaining solid mass of follicular tissue that grows and produces estrogen and progesterone in the ovary.

20. Fig

21. Fig

22. Male Reproductive Tract
Testes – male gonads; many highly coiled tubes; suspended in scrotum (not all mammals).
Seminiferous Tubules – site of spermatogenesis and sperm maturation.
Leydig (Interstitial) Cells – in between tubules; secrete testosterone.
Sertoli (Sustentacular ) Cells – induce primary spermatocytes into spermatogenesis.

23. Male Accessory Glands
Seminal Vesicles (pair) – secretions of fructose, prostaglandins (smooth muscle contraction), fibrinogen (coagulant); alkaline.
Prostate Gland – largest of the glands; secretes an antibiotic, fibrinolysin (anticoagulant).
Bulbourethral Glands (pair) – pre-ejaculation secretion of alkaline mucus to neutralize acidity of urethra (acidic urine); may have sperm present.

24. Increasing Levels of LH
Figure 46.11

25. Increasing FSH + Testosterone
Figure 46.12

28. Female Mammal Reproductive Cycles
Menstrual Cycle – some primates and humans; endometrium shed through the cervix and vagina; bleeding = menstruation; may mate regardless of ovulatory status.
Estrous Cycle – all other mammals; most of the endometrium reabsorbed by uterus; little bleeding; marked by intense mating activity – estrus (heat) – only time receptive to mating (ovulating).

29. Human Female Reproductive Cycle
An integrated cycle involving two organs uterus and ovaries.
Uterine Cycle – changes in the uterus (menstrual cycle); caused by the ovarian cycle.
Ovarian Cycle – cyclic events in the ovaries.

30. Reproductive Hormones You Need to Know
Gonarotropin-releasing Hormone (GnRH)
Follicle-stimulating Hormone (FSH)
Luteinizing Hormone (LH)
Estrogen
Progesterone
Testosterone
Inhibin
Human Chorionic Gonadotropin (HCG)

31. Fig

32. Negative Feedback Inhibin Fig. 46.14 (Interstitial Cells)
(Sustentacular Cells)
Fig

33. Figure 46.15a, b Cleavage (cell division) begins in the oviduct
as the embryo is moved
toward the uterus
by peristalsis and the
movements of cilia.
Cleavage continues. By the time the embryo reaches the uterus, it is a ball of cells. It floats in the uterus for several days, nourished by endometrial secretions. It becomes a blastocyst.
Fertilization occurs. A sperm
enters the oocyte; meiosis of
the oocyte finishes; and the
nuclei of the ovum and sperm
fuse, producing a zygote.
The blastocyst implants
in the endometrium
about 7 days after conception.
Ovulation releases a
secondary oocyte, which
enters the oviduct.
Figure 46.15a, b

34. Fig

35. Fig

37. Fig

38. The process of labor has three stages
Figure 46.19
Placenta
Umbilical
cord
Uterus
Cervix
Dilation of the cervix
Expulsion: delivery of the infant
(detaching)
Delivery of the placenta 1 2 3

39. Fig