1. Chapter 46: Animal Reproduction
Figure 46.1

2. A population transcends finite life spans only by reproduction

3. Asexual v. sexual reproduction
Asexual, new individuals whose genes all come from one parent

4. Sexual reproduction: creation of offspring by the fusion of male and female gametes to form a zygote
Female gamete is the egg
Male gamete is the sperm

5. Asexual Reproduction (inverts)
Fission
Figure 46.2

6. Budding
Fragmentation

7. Reproductive Cycles and Patterns
Related to changing seasons
Controlled by hormones and environmental cues

8. Animals may reproduce exclusively asexually or sexually
Or they may alternate between the two
Some animals reproduce by parthenogenesis
A process in which an egg develops without being fertilized

9. Parthenogenesis Figure 46.3a, b Time Ovary size Hormones Behavior
Ovulation
Progesterone
Estrogen
Female- like
Male- like
(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.

10. Hermaphroditism
Each individual has both male and female reproductive systems

11. Another remarkable reproductive pattern is sequential hermaphroditism
individual reverses its sex during its lifetime
Figure 46.4

12. External fertilization
Figure 46.5
Eggs

13. Internal fertilization fertilization occurs within the reproductive tract  terrestrial adaptation

14. Embryos of many terrestrial animals
Develop in eggs that can withstand harsh environments
Instead of secreting a shell around the embryo
Many animals retain the embryo, which develops inside the female

15. Parental care
survival of offspring
Figure 46.6

16. Simple animal/ complex reproductive system
Figure 46.7
Male organs:
Female organs:
Genital pore
(Excretory pore)
Seminal
receptacle
(Digestive tract)
Testis 1
Vas efferens 2
Sperm duct (vas deferens) 3
Seminal vesicle 4
Ovary
Oviduct
Yolk duct
Yolk gland
Uterus

17. Most insects separate sexes
Ovary 1
Accessory gland 4
Ejaculatory duct 1
Testis
Oviduct
Spermatheca 2 5
Penis
Vas deferens
Vagina 3 3
Seminal vesicle
Accessory gland
(a) Male honeybee. Sperm form in the testes, pass through the sperm duct (vas deferens), and are stored in the seminal vesicle. The male ejaculates sperm along with fluid from the accessory glands. (Males of some species of insects and other arthropods have appendages called claspers that grasp the female during copulation.)
(b) Female honeybee. Eggs develop in the ovaries and then pass through the oviducts and into the vagina. A pair of accessory glands (only one is shown) add protective secretions to the eggs in the vagina. After mating, sperm are stored in the spermatheca, a sac connected to the vagina by a short duct.
Figure 46.8a, b

18. Contains many follicles
Ovaries
Female gonads
Contains many follicles
one egg cell surrounded by layers of follicle cells

19. Ovulation
egg cell expelled from the follicle
Remaining follicular tissue forms a mass called the corpus luteum, which secretes hormones

20. The egg cell is released
Oviducts and Uterus
The egg cell is released
Near the opening of the oviduct, or fallopian tube
Cilia in the tube
Convey the egg to the uterus

21. Testes
Male gonads
Highly coiled tubes (seminiferous tubules) where sperm form

22. Production of normal sperm
Cannot occur at the body temperatures of most mammals
Testes are outside the abdominal cavity lower temperature

23. Gametogenesis
Based on meiosis

24. Primary germ cell in embryo
Oogenesis
Ovary
Primary germ cell in embryo
Differentiation
Oogonium
in ovary
Mitotic
division
Primary oocyte,
arrested in prophase
of meiosis I
(present at birth)
Completion of meiosis I
and onset of meiosis II
Primary
oocyte
within
follicle
Secondary oocyte,
arrested at meta-
phase of meiosis II
First
polar
body
Ovulation
Entry of
sperm triggers
completion of
meiosis II
Ovum
Growing
Mature follicle
Ruptured
Ovulated
secondary oocyte
Corpus luteum
Degenerating
corpus luteum 2n n
Figure 46.11

25. Secondary spermatocyte
Spermatogenesis
Epididymis
Seminiferous tubule
Testis
Cross section
of seminiferous
tubule 2n
Spermatogonium
Mitotic division,
producing large numbers
of spermatogonia
Sertoli cell
nucleus
Differentiation and onset of meiosis I
Primary spermatocyte
(in prophase of meiosis I) 2n
Meiosis I completed n n
Secondary spermatocyte
Meiosis II
Spermatids
(at two stages of
differentiation) n n n n
Early
spermatids
Differentiation
(Sertoli cells provide
nutrients)
Sperm cells n n n n
Neck
Head
Midpiece
Tail
Mitochondria
Nucleus
Figure 46.12
Acrosome

26. Oogenesis v. Spermatogenesis
Cytokinesis is unequal (oogenesis), almost all the cytoplasm monopolized by a single daughter cell, the secondary oocyte

27. 2. Sperm produced continuously
not the case in oogenesis
3. Oogenesis has long “resting” periods
While spermatogenesis produces sperm in uninterrupted sequence

28. The Human Female Reproductive Cycle
One integrated cycle involving two organs, the uterus and ovaries

29. Control by hypothalamus Uterine (menstrual) cycle
Human female reproductive cycle
Figure 46.13a–e
Control by hypothalamus
Inhibited by combination of
estrogen and progesterone
Stimulated by high levels
of estrogen
Inhibited by low levels of
estrogen
Hypothalamus
Anterior pituitary
GnRH
FSH LH
Pituitary gonadotropins
in blood
FSH and LH stimulate
follicle to grow
LH surge triggers
ovulation
Ovarian cycle
Growing follicle
Mature
follicle
Corpus
luteum
Degenerating
corpus luteum
Estrogen secreted
by growing follicle in
increasing amounts
Progesterone and
estrogen secreted
by corpus luteum
Follicular phase
Luteal phase
Ovulation
Ovarian hormones
Peak causes
LH surge
Estrogen
Progesterone
Estrogen level
very low
Progesterone and estro-
gen promote thickening
of endometrium
Uterine (menstrual) cycle
Endometrium
Menstrual flow phase
Proliferative phase
Secretory phase 5 10 14 15 20 25 28
Days 1
(a)
(b)
(c)
(d)
(e) 3 6 7 8 4 2 9

30. The Ovarian Cycle
Hormones(LH and FSH) f/ pituitary stimulate follicle growth, which results in ovulation
Following ovulation, follicular tissue transforms into the corpus luteum

31. The Uterine (Menstrual) Cycle
Cycle after cycle
The maturation and release of egg cells from the ovary are integrated with changes in the uterus
If an embryo has not implanted in the endometrium by the end of the secretory phase
A new menstrual flow commences

32. Male Reproductive cycle
Androgen secretion and sperm production
controlled by hypothalamic and pituitary hormones
Stimuli from other
areas in the brain
Hypothalamus
GnRH from the
hypothalamus reg-
ulates FSH and LH
release from the
anterior pituitary.
FSH acts on the
Sertoli cells of the
seminiferous
tubules, promoting
spermatogenesis.
LH stimulates the
Leydig cells to make
testosterone, which
in turn stimulates
sperm production.
Anterior
pituitary
Negative
feedback
Leydig cells
make
testosterone
Primary and
secondary sex
characteristics
Sertoli cells
Spermatogenesis
Testis
Figure 46.14

33. From ovulation to implantation Implantation of blastocyst
Fertilization of an egg by a sperm, conception occurs in the oviduct
Cleavage (cell division)
begins in the oviduct
as the embryo is moved
toward the uterus
by peristalsis and the
movements of cilia. 3
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. 4
Figure 46.15a, b
Ovary
Uterus
Endometrium
From ovulation to implantation
Inner cell mass
Cavity
Blastocyst
Trophoblast
(a)
Implantation of blastocyst
(b)
Fertilization occurs. A sperm
enters the oocyte; meiosis of
the oocyte finishes; and the
nuclei of the ovum and sperm
fuse, producing a zygote. 2
Ovulation releases a
secondary oocyte, which
enters the oviduct. 1
The blastocyst implants
in the endometrium
about 7 days after conception. 5

34. After fertilization
 zygote  cleavage blastocyst  implantation in the endometrium

35. First Trimester
time of most radical change for both the mother and the embryo

36. first 2 to 4 weeks embryo obtains nutrients directly from the endometrium
Placenta forms

37. Blood from the embryo
Travels to the placenta through arteries of the umbilical cord and returns via the umbilical vein
Placenta
Umbilical cord
Chorionic villus
containing fetal
capillaries
Maternal blood
pools
Uterus
Fetal arteriole
Fetal venule
Maternal portion
of placenta
Fetal portion of
placenta (chorion)
Umbilical arteries
Umbilical vein
Maternal
arteries
veins
Figure 46.16

38. 1st trimester main period of organogenesis
Figure 46.17a–c
(a) 5 weeks. Limb buds, eyes, the heart, the liver, and rudiments of all other organs have started to develop in the embryo, which is only about 1 cm long.
(b) 14 weeks. Growth and development of the offspring, now called a fetus, continue during the second trimester. This fetus is about 6 cm long.
(c) 20 weeks. By the end of the second trimester (at 24 weeks), the fetus grows to about 30 cm in length.

39. Second Trimester
Fetus grows and is very active

40. Third Trimester
Fetus fills the available space within the embryonic membranes

41. The Mother’s Immune Tolerance of the Embryo and Fetus
May be due to the suppression of the immune response in her uterus

42. Amniocentesis and chorionic villus sampling
Invasive techniques in which amniotic fluid or fetal cells are obtained for genetic analysis

43. Noninvasive procedures
Ultrasound imaging to detect fetal condition
Figure 46.21
Head
Body