Fig. 19.1 Mammary gland (in breast) Uterine tube Seminal vesicle Ovary Copyright © McGraw-Hill Education. Permission required for reproduction or display. Mammary gland (in breast) Uterine tube Seminal vesicle Ovary Ductus deferens Prostate gland Uterus Vagina Epididymis Penis Testis (a) (b)

Fig. 19.4 Basement membrane Interstitial cells (Leydig cells) Copyright © McGraw-Hill Education. Permission required for reproduction or display. Basement membrane Interstitial cells (Leydig cells) Sustentacular cell Spermatogonia Rete testis Efferent ductules Testis Seminiferous tubule Primary and secondary spermatocytes Epididymis Duct of epididymis Spermatids (b) Sperm cells Septa Acrosome Lobules with coiled seminiferous tubules Head Ductus deferens Nucleus Midpiece Centriole (a) Tail (c) Mitochondria Tail (d)

Fig. 19.3 Ureter Seminal vesicle Urinary bladder Ejaculatory duct Copyright © McGraw-Hill Education. Permission required for reproduction or display. Ureter Seminal vesicle Urinary bladder Ejaculatory duct Rectum Prostate gland Bulbourethral gland Anus Urethra Penis Ductus deferens Epididymis Glans penis Testis Prepuce Scrotum Medial view

Fig. 19.4 Basement membrane Interstitial cells (Leydig cells) Copyright © McGraw-Hill Education. Permission required for reproduction or display. Basement membrane Interstitial cells (Leydig cells) Sustentacular cell Spermatogonia Rete testis Efferent ductules Testis Seminiferous tubule Primary and secondary spermatocytes Epididymis Duct of epididymis Spermatids (b) Sperm cells Septa Acrosome Lobules with coiled seminiferous tubules Head Ductus deferens Nucleus Midpiece Centriole (a) Tail (c) Mitochondria Tail (d)

Fig. 19.2 Copyright © McGraw-Hill Education. Permission required for reproduction or display. First Meiotic Division (Meiosis I) Second Meiotic Division (Meiosis II) (continued from the bottom of previous column) 1 Early prophase I The duplicated chromosomes become visible chromatids. Centromere Chromosome 6 Prophase II Each chromosome consists of two chromatids. Nucleus Chromatids Centrioles 2 Middle prophase I Pairs of chromosomes synapse. Crossing over may occur at this stage. Pair of chromosomes Spindle fibers 3 Metaphase I Pairs of chromosomes align along the center of the cell. Random assortment of chromosomes occurs. 7 Metaphase II Chromosomes align along the center of the cell. Equatorial plane 4 Anaphase I Chromosomes move apart to opposite sides of the cell. 8 Anaphase II Chromatids separate, and each is now called a chromosome. Cleavage furrow 5 Telophase I New nuclei form, and the cell divides. Each cell now has two sets of half the chromosomes. 9 Telophase II New nuclei form around the chromosomes. The cells divide to form four daughter cells with half as many chromosomes as the parent cell. Prophase II (top of next column)

Fig. 19.5 Copyright © McGraw-Hill Education. Permission required for reproduction or display. 1 Spermatogonia are the cells from which sperm cells arise. The spermatogonia divide by mitosis. One daughter cell remains a spermatogonium that can divide again by mitosis. cell becomes a primary spermatocyte. 1 Spermatogonium (germ cell) 46 46 Mitotic division 46 Daughter cell Sustentacular cell Primary spermatocyte 46 2 The primary spermatocyte divides by meiosis to form secondary spermatocytes. First meiotic division 2 Secondary spermatocyte 23 23 3 The secondary spermatocytes divide by meiosis to form spermatids. 3 Second meiotic division Spermatid 23 23 23 23 4 The spermatids differentiate to form sperm cells. 4 Spermatid becoming a sperm cell 23 23 23 23 23 23 23 23 Lumen of seminiferous tubule Sperm cells

Table 19.2

Fig. 19.7 1 Gonadotropin-releasing hormone (GnRH) from the Copyright © McGraw-Hill Education. Permission required for reproduction or display. 1 Gonadotropin-releasing hormone (GnRH) from the hypothalamus stimulates the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the anterior pituitary. GnRH Hypothalamus Stimulatory 2 LH stimulates testosterone secretion from the interstitial cells. Inhibitory 3 FSH stimulates sustentacular cells of the seminiferous tubules to increase spermatogenesis and to secrete inhibin. Anterior pituitary LH, FSH 1 5 4 Testosterone has a stimulatory effect on the sustentacular cells of the seminiferous tubules, as well as on the development of reproductive organs and secondary sexual characteristics. LH FSH Inhibin 2 3 6 Interstitial cells of testis Sustentacular cells of seminiferous tubules 5 Testosterone has a negative-feedback effect on the hypothalamus and pituitary to reduce GnRH, LH, and FSH secretion. Testosterone 4 Development of reproductive organs and secondary sexual characteristics 6 Inhibin has a negative-feedback effect on the anterior pituitary to reduce FSH secretion. Spermatogenesis

Fig. 19.1 Mammary gland (in breast) Uterine tube Seminal vesicle Ovary Copyright © McGraw-Hill Education. Permission required for reproduction or display. Mammary gland (in breast) Uterine tube Seminal vesicle Ovary Ductus deferens Prostate gland Uterus Vagina Epididymis Penis Testis (a) (b)

Fig. 19.8 Uterine tube Vertebral column Ovary Uterus Urinary bladder Copyright © McGraw-Hill Education. Permission required for reproduction or display. Uterine tube Vertebral column Ovary Uterus Urinary bladder Pubic symphysis Cervix of uterus Anterior Posterior Mons pubis Rectum Urethra Clitoris Vagina Urethral orifice Vaginal orifice Labia minora Labia majora Medial view

Fig. 19.10 Mesovarium Blood vessels Primordial follicles Copyright © McGraw-Hill Education. Permission required for reproduction or display. Mesovarium Blood vessels Primordial follicles Primary oocyte Degenerated corpus luteum Primary follicles Visceral peritoneum Granulosa cells Zona pellucida Outer part of ovary Inner part of ovary Degenerating follicle Secondary follicle Vesicles Zona pellucida Corpus luteum Theca Zona pellucida Primary oocyte Cumulus cells Mature, or graafian, follicle Antrum Theca

Fig. 19.9 Uterine tube Mesovarium Uterine cavity Suspensory ligament Copyright © McGraw-Hill Education. Permission required for reproduction or display. Uterine tube Mesovarium Uterine cavity Suspensory ligament Ovary Fimbria Broad ligament Ampulla of uterine tube Fundus Ovary Uterine tube Broad ligament Ovarian ligament Uterus Body Round ligament Endometrium Myometrium (muscular layer) Perimetrium (serous layer) Broad ligament (cut) Cervix Cervical canal Vagina (cut) Opening of cervix Anterior view

Fig. 19.8 Uterine tube Vertebral column Ovary Uterus Urinary bladder Copyright © McGraw-Hill Education. Permission required for reproduction or display. Uterine tube Vertebral column Ovary Uterus Urinary bladder Pubic symphysis Cervix of uterus Anterior Posterior Mons pubis Rectum Urethra Clitoris Vagina Urethral orifice Vaginal orifice Labia minora Labia majora Medial view

Fig. 19.14 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Hypothalamus GnRH Pituitary gland LH Pituitary gland FSH Degenerating corpus luteum Corpus luteum Developing follicles Ovulation Estrogen Ovary Progesterone Endometrium Uterus 2 4 6 8 10 12 14 16 18 20 22 24 26 28 days Menses Proliferative phase Secretory phase Menses

Fig. 19.2 Copyright © McGraw-Hill Education. Permission required for reproduction or display. First Meiotic Division (Meiosis I) Second Meiotic Division (Meiosis II) (continued from the bottom of previous column) 1 Early prophase I The duplicated chromosomes become visible chromatids. Centromere Chromosome 6 Prophase II Each chromosome consists of two chromatids. Nucleus Chromatids Centrioles 2 Middle prophase I Pairs of chromosomes synapse. Crossing over may occur at this stage. Pair of chromosomes Spindle fibers 3 Metaphase I Pairs of chromosomes align along the center of the cell. Random assortment of chromosomes occurs. 7 Metaphase II Chromosomes align along the center of the cell. Equatorial plane 4 Anaphase I Chromosomes move apart to opposite sides of the cell. 8 Anaphase II Chromatids separate, and each is now called a chromosome. Cleavage furrow 5 Telophase I New nuclei form, and the cell divides. Each cell now has two sets of half the chromosomes. 9 Telophase II New nuclei form around the chromosomes. The cells divide to form four daughter cells with half as many chromosomes as the parent cell. Prophase II (top of next column)

Number of primary oocytes Fig. 19.11 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Oocyte Maturation Follicle Maturation Age 1 Oogonia give rise to oocytes. Before birth, oogonia multiply by mitosis. During development of the fetus, many oogonia begin meiosis, but stop in prophase I and are now called primary oocytes. They remain in this state until puberty. Oogonia Before birth 46 46 Mitotic division Daughter cell 46 1 2 Primary oocyte Primordial follicle 2 Before birth, the primary oocytes become surrounded by a single layer of granulosa cells, creating a primordial follicle. These are present until puberty. Primary oocyte 46 First meiotic division begins and then stops Granulosa cells Number of primary oocytes decreases to 300,000 Birth to puberty 3 After puberty, primordial follicles develop into primary follicles when the granulosa cells enlarge and increase in number. Puberty to menopause 3 Primary follicles Primary oocyte Granulosa cells 4 Secondary follicles form when fluid-filled vesicles develop and theca cells arise on the outside of the follicle. Zona pellucida Primary oocyte 4 Secondary follicle Zona pellucida Fluid-filled vesicles Granulosa cells 5 Mature follicles form when the vesicles create a single antrum. Theca 5 Mature (graafian) follicle 6 Just before ovulation, the primary oocyte completes meiosis I, creating a secondary oocyte and a nonviable polar body. First meiotic division completed just before ovulation Zona pellucida 6 Cumulus cells Antrum 7 The secondary oocyte begins meiosis II, but stops at metaphase II. Theca Secondary oocyte First polar body (may divide to form two polar bodies) 23 23 Second meiotic division begins and then stops Granulosa cells being converted to corpus luteum cells 8 During ovulation, the secondary oocyte is released from the ovary. 7 Ovulation 9 The secondary oocyte only completes meiosis II if it is fertilized by a sperm cell. The completion of meiosis II forms an oocyte and a second polar body. Fertilization is complete when the oocyte nucleus and the sperm cell nucleus unite, creating a zygote. Secondary oocyte Secondary oocyte 23 8 Zona pellucida Second polar body 9 Sperm cell unites with secondary oocyte Cumulus cells 10 23 23 Zygote 23 46 10 Following ovulation, the granulosa cells divide rapidly and enlarge to form the corpus luteum. Corpus luteum Second meiotic division completed after sperm cell unites with the secondary oocyte 11 11 The corpus luteum degenerates to form a scar, or corpus albicans. Corpus albicans Fertilization

Table 19.3