1. Chapter 46.4 and 46.5
Animal Reproduction

2. Primordial germ cell in embryo
Fig c Fill in the blanks.
During _____________________,
_____ sperm cells are produced in the
testis.
Primordial germ cell in embryo
Mitotic divisions
Spermatogonial stem cell 2n
Mitotic divisions
Spermatogonium 2n
Mitotic divisions
Primary spermatocyte 2n
Meiosis I
Secondary spermatocyte n n
Meiosis II
Figure Human gametogenesis
Early spermatid n n n n
Differentiation (Sertoli cells provide nutrients)
Sperm n n n n

3. Fig. 46-12d What are the functions of the underlined structures?
Neck
Tail
Midpiece
Head
Plasma membrane
Mitochondria
Nucleus
Acrosome
Figure Human gametogenesis

4. Primary oocyte within follicle
Fig f Match the description to each box by placing the number next to the image.
What the ruptured follicle develops into after the release of the oocyte.
Arrested at Metaphase II, the secondary oocyte is released during ovulation cycle.
Develops during embryonic stage but is arrested at prophase I before birth.
It’s development occurs at the beginning of puberty.
What happens if the oocyte is not fertilized.
Is stimulated by FSH to resume growth and development.
Ovary
Ruptured follicle
Primary oocyte within follicle
Ovulated secondary oocyte
Growing follicle
Figure Human gametogenesis
Corpus luteum
Mature follicle
Degenerating corpus luteum

5. Figure 46.12 Human gametogenesis
Fig g Why is the secondary oocyte so large compared to the polar bodies?
In embryo
Primordial germ cell
Mitotic divisions 2n
Oogonium
Mitotic divisions
Primary oocyte (present at birth), arrested in prophase of meiosis I 2n
Completion of meiosis I and onset of meiosis II
First polar body n n
Secondary oocyte, arrested at metaphase of meiosis II
Ovulation, sperm entry
Figure Human gametogenesis
Completion of meiosis II
Second polar body n
Fertilized egg n

6. – – – Hypothalamus GnRH Anterior pituitary FSH LH Sertoli cells
Fig How would a mutation in Leydig cells that caused overproduction of LH receptors affect this system? –
Hypothalamus
GnRH – –
Anterior pituitary
FSH LH
Negative feedback
Negative feedback
Sertoli cells
Leydig cells
Figure Hormonal control of the testes
Inhibin
Spermatogenesis
Testosterone
Testis

7. Degenerating corpus luteum
Fig How do birth controls pills prevent follicular development and ovulation?
(a)
Control by hypothalamus
Inhibited by combination of estradiol and progesterone
Hypothalamus –
Stimulated by high levels of estradiol 1
GnRH +
Anterior pituitary
Inhibited by low levels of estradiol – 2
FSH LH
(b)
Pituitary gonadotropins in blood 6 LH
FSH
FSH and LH stimulate follicle to grow
LH surge triggers ovulation 3
(c)
Ovarian cycle 7 8
Growing follicle
Maturing follicle
Corpus luteum
Degenerating corpus luteum
Follicular phase
Ovulation
Luteal phase
Estradiol secreted by growing follicle in increasing amounts
Progesterone and estradiol secreted by corpus luteum 4
(d)
Ovarian hormones in blood
Peak causes LH surge 5 10
Estradiol
Progesterone 9
Estradiol level very low
Progesterone and estra- diol promote thickening of endometrium
(e)
Uterine (menstrual) cycle
Endometrium
Menstrual flow phase Proliferative phase
Secretory phase
Days | | | | | | | | 5 10 14 15 20 25 28

8. Degenerating corpus luteum
Fig a How is the inhibition of ovulation by the use of oral contraceptives related to a lower incidence of ovarian cancer?
(a)
Control by hypothalamus
Inhibited by combination of estradiol and progesterone
Hypothalamus –
Stimulated by high levels of estradiol
GnRH +
Anterior pituitary
Inhibited by low levels of estradiol –
FSH LH
(b)
Pituitary gonadotropins in blood LH
FSH
FSH and LH stimulate follicle to grow
LH surge triggers ovulation
(c)
Ovarian cycle
Corpus luteum
Degenerating corpus luteum
Growing follicle
Maturing follicle
Follicular phase
Ovulation
Luteal phase
Days | | | | | | | | 5 10 14 15 20 25 28

9. Ovarian hormones in blood Peak causes LH surge
Fig b Why does a female taking oral contraceptives still experience a menstrual cycle? How is this different than an estrous cycle?
(d)
Ovarian hormones in blood
Peak causes LH surge
Estradiol
Progesterone
Estradiol level very low
Ovulation
Progesterone and estra- diol promote thickening of endometrium
(e)
Uterine (menstrual) cycle
Endometrium
Figure The reproductive cycle of the human female
Menstrual flow phase Proliferative phase
Secretory phase
Days | | | | | | | | 5 10 14 15 20 25 28