Figure 46.0 Frogs mating Chap46 Animal Reproduction

Asexual reproduction Budding Fragmentation Regeneration

Animal reproductive pattern Parthenogenesis Sequential Parthenogenesis: Protogynous (female): Fig 46.3 Protogynous (male):

Figure 46.2 Sexual behavior in parthenogenetic lizards (a)

Figure 46.3 Sex reversal in a sequential hermaphrodite

Figure 46.x2 Sea urchin sperm fertilizing an egg

Figure 46.9 Reproductive anatomy of the human female

Figure 46.9 Reproductive anatomy of the human female (continued)

Figure Reproductive anatomy of the human male (continued)

Figure Reproductive anatomy of the human male

Figure 46.9x Ovary (left) and follicle (right)

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 follicle Mature follicle Ruptured follicle Ovulated secondary oocyte Corpus luteum Degenerating corpus luteum 2n2n 2n2n n n n n Figure Oogenesis is the development of mature ova

Figure 46.13b Oogenesis

Spermatogenesis is the production of mature sperm Epididymis Seminiferous tubule Testis Cross section of seminiferous tubule Sertoli cell nucleus Lumen of Seminiferous tubule 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 2n2n 2n2n n n nn nn n n nn Figure Differentiation and onset of meiosis I

Figure Spermatogenesis

Figure Structure of a human sperm cell

The reproductive cycle of the human female 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 FSHLH Pituitary gonadotropins in blood LH FSH 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 phaseOvulation Ovarian hormones in blood 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 Days 1 (a) (b) (c) (d) (e)

Positive and negative feedback Positive : Follicular phase: LH  estrogen Negative: Luteal phase:  LH and FSH  Estrogen and progesterone

Androgen secretion and sperm production Are both 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

Fertilization of an egg by a sperm, conception Occurs in the oviduct Figure 46.15a, b Ovary Uterus Endometrium From ovulation to implantation Endometrium Inner cell mass Cavity Blastocyst Trophoblast (a) Implantation of blastocyst(b) Ovulation releases a secondary oocyte, which enters the oviduct. 1 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 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 The blastocyst implants in the endometrium about 7 days after conception. 5

Figure Placental circulation

Figure Human fetal development

Figure Hormonal induction of labor

Figure The three stages of labor

Mechanisms of some contraceptive methods Figure Male Female Method Event Method Production of viable sperm Production of viable oocytes Vasectomy Combination birth control pill (or injection, patch, or vaginal ring) Sperm transport down male duct system Ovulation Abstinence Condom Coitus interruptus (very high failure rate) Sperm deposited in vagina Capture of the oocyte by the oviduct Abstinence Tubal ligation Spermicides; diaphragm; cervical cap; progestin alone (minipill, implant, or injection) Sperm movement through female reproductive tract Transport of oocyte in oviduct Meeting of sperm and oocyte in oviduct Morning-after pill (MAP) Union of sperm and egg Implantation of blastocyst in properly prepared endometrium Birth Progestin alone

Figure Mechanisms of some contraceptive methods

Figure Ultrasound imaging