Chapter 46: Animal Reproduction

Figure 46.8 Insect reproductive anatomy Ovary 1 Accessory gland 4 Ejaculatory duct 1 Testis Oviduct 2 Spermatheca 5 Penis 2 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.

Vagina Uterus Cervix Ovaries Oviduct Uterine wall Endometrium Follicles Corpus luteum

Figure 46.10 Reproductive anatomy of the human male Erectile tissue of penis Prostate gland (Urinary bladder) Bulbourethral gland Vas deferens Epididymis Testis Seminal vesicle (behind bladder) Urethra Scrotum Glans penis

Figure 46.11 Human 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 Second polar body

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

Figure 46.14 Hormonal control of the testes 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 46.17 Human fetal development 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. (a) 14 weeks. Growth and development of the offspring, now called a fetus, continue during the second trimester. This fetus is about 6 cm long. (b) 20 weeks. By the end of the second trimester (at 24 weeks), the fetus grows to about 30 cm in length. (c)

Figure 46.18 A model for the induction of labor Estrogen Oxytocin from ovaries from fetus and mother's posterior pituitary Induces oxytocin receptors on uterus Stimulates uterus to contract Stimulates placenta to make Prostaglandins Stimulate more contractions of uterus Positive feedback

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