Chapter 46.4 and 46.5 Animal Reproduction

Primordial germ cell in embryo Fig. 46-12c 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 46.12 Human gametogenesis Early spermatid n n n n Differentiation (Sertoli cells provide nutrients) Sperm n n n n

Fig. 46-12d What are the functions of the underlined structures? Neck Tail Midpiece Head Plasma membrane Mitochondria Nucleus Acrosome Figure 46.12 Human gametogenesis

Primary oocyte within follicle Fig. 46-12f 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 46.12 Human gametogenesis Corpus luteum Mature follicle Degenerating corpus luteum

Figure 46.12 Human gametogenesis Fig. 46-12g 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 46.12 Human gametogenesis Completion of meiosis II Second polar body n Fertilized egg n

– – – Hypothalamus GnRH Anterior pituitary FSH LH Sertoli cells Fig. 46-13 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 46.13 Hormonal control of the testes Inhibin Spermatogenesis Testosterone Testis

Degenerating corpus luteum Fig. 46-14 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

Degenerating corpus luteum Fig. 46-14a 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

Ovarian hormones in blood Peak causes LH surge Fig. 46-14b 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 46.14 The reproductive cycle of the human female Menstrual flow phase Proliferative phase Secretory phase Days | | | | | | | | 5 10 14 15 20 25 28