Reproductive Systems PDF

The Reproductive Systems The reproductive systems and homeostasis The male and female reproductive organs work together to produce offspring. In addition, the female reproductive organs contri...

The Reproductive Systems The reproductive systems and homeostasis The male and female reproductive organs work together to produce offspring. In addition, the female reproductive organs contribute to sustaining the growth of embryos and fetuses. Sexual reproduction is the process by which organisms produce offspring by making germ cells called gametes (GAM-ēts ⫽ spouses). After the male gamete (sperm cell) unites with the female gamete (secondary oocyte)—an event called fertilization ˉ -shun)—the resulting cell contains one set of chromosomes from each parent. Males and females have (fer⬘-til-i-ZA anatomically distinct reproductive organs that are adapted for producing gametes, facilitating fertilization, and, in females, sustaining the growth of the embryo and fetus. The male and female reproductive organs can be grouped by function. The gonads—testes in males and ovaries in females— produce gametes and secrete sex hormones. Various ducts then store and transport the gametes, and accessory sex glands produce substances that protect the gametes and facilitate their movement. Finally, supporting structures, such as the penis in males and the uterus in females, assist the delivery of gametes, and the uterus is also the site for the growth of the embryo and during fetus du pregnancy. uring pregn ynecolog (gı̄-ne-KOL-oˉ-jē; gyneco- ⫽ woman; -logy ⫽ study of) is the Gynecology G specialized branch of medicine concerned with the diagnosis and special treatment of diseases of the female reproductive system. As noted in treat Chapter 26, urology (uˉ-ROL-oˉ-jē) is the study of the urinary system. Ch Urologists also diagnose and treat diseases and disorders of the U male reproductive system. The branch of medicine that deals with male disorders, especially infertility and sexual dysfunction, is called andrology (an-DROL-oˉ-jē; andro- ⫽ masculine). m sco ew /N ide ldw or W n io ct n ne o kC Stoc s ge BAO- Ima Did you ever wonder how breast augmentation D and breast reduction are performed 1041 1042 CHAPTER 28 THE REPRODUCTIVE SYSTEMS 28.1 Male Reproductive System Scrotum OBJECTIVES The scrotum (SKRŌ-tum ⫽ bag), the supporting structure for Describe the location, structure, and functions of the the testes, consists of loose skin and underlying subcutaneous organs of the male reproductive system. layer that hangs from the root (attached portion) of the penis Discuss the process of spermatogenesis in the testes. (Figure 28.1a). Externally, the scrotum looks like a single pouch of skin separated into lateral portions by a median ridge The organs of the male reproductive system include the testes, called the raphe (RAˉ-fē ⫽ seam). Internally, the scrotal sep- a system of ducts (epididymis, ductus deferens, ejaculatory tum divides the scrotum into two sacs, each containing a single ducts, and urethra), accessory sex glands (seminal vesicles, testis (Figure 28.2). The septum is made up of a subcutaneous prostate, and bulbourethral glands), and several supporting layer and muscle tissue called the dartos muscle (DAR-toˉs ⫽ structures, including the scrotum and the penis (Figure 28.1). skinned), which is composed of bundles of smooth muscle fibers. The testes (male gonads) produce sperm and secrete hormones. The dartos muscle is also found in the subcutaneous layer of the The duct system transports and stores sperm, assists in their scrotum. Associated with each testis in the scrotum is the cre- maturation, and conveys them to the exterior. Semen contains master muscle (krē-MAS-ter ⫽ suspender), a series of small sperm plus the secretions provided by the accessory sex glands. bands of skeletal muscle that descend as an extension of the The supporting structures have various functions. The penis de- internal oblique muscle through the spermatic cord to surround livers sperm into the female reproductive tract and the scrotum the testes. supports the testes. FUN CTI ON S OF THE MA LE RE PRO DU CTIVE SYSTEM Figure 28.1 Male organs of reproduction and surrounding structures. 1. The testes produce sperm and the male sex hormone testosterone. Reproductive organs are adapted for producing new individuals 2. The ducts transport, store, and assist in maturation of sperm. and passing on genetic material from one generation to the next. 3. The accessory sex glands secrete most of the liquid portion of semen. 4. The penis contains the urethra, a passageway for ejaculation of semen and excretion of urine. Sagittal plane Sacrum Peritoneum Seminal vesicle Urinary bladder Vesicorectal pouch Ductus (vas) deferens Coccyx Suspensory ligament Rectum of penis Ampulla of ductus Pubic symphysis (vas) deferens Ejaculatory duct Prostate Prostatic urethra Deep muscles of perineum Intermediate urethra Bulbourethral (Cowper’s) gland Anus Corpus cavernosum penis Spongy urethra Body of penis Root of penis Corpus spongiosum penis Corona Epididymis Glans penis Prepuce (foreskin) External urethral orifice Testis Scrotum (a) Sagittal section  28.1 MALE REPRODUCTIVE SYSTEM 1043 SUPERIOR Seminal vesicle Urinary bladder (opened) Ductus (vas) deferens Prostatic urethra Prostate Ejaculatory duct Pubic symphysis Rectum Corpus cavernosum penis Intermediate urethra Corpus spongiosum penis Root of penis Body of penis Bulbospongiosus muscle Testis Spongy urethra Corona Glans penis POSTERIOR ANTERIOR (b) Sagittal section What are the groups of reproductive organs in males, and what are the functions of each group? The location of the scrotum and the contraction of its muscle Testes fibers regulate the temperature of the testes. Normal sperm produc- tion requires a temperature about 2–3⬚C below core body tempera- The testes (TES-tēz ⫽ witness), or testicles, are paired oval ture. This lowered temperature is maintained within the scrotum glands in the scrotum measuring about 5 cm (2 in.) long and 2.5 because it is outside the pelvic cavity. In response to cold tempera- cm (1 in.) in diameter (Figure 28.3). Each testis (singular) has a tures, the cremaster and dartos muscles contract. Contraction of the mass of 10–15 grams. The testes develop near the kidneys, in the cremaster muscles moves the testes closer to the body, where they posterior portion of the abdomen, and they usually begin their can absorb body heat. Contraction of the dartos muscle causes the descent into the scrotum through the inguinal canals (passage- scrotum to become tight (wrinkled in appearance), which reduces ways in the lower anterior abdominal wall; see Figure 28.2) dur- heat loss. Exposure to warmth reverses these actions. ing the latter half of the seventh month of fetal development. Figure 28.2 The scrotum, the supporting structure for the testes. Internal oblique muscle Aponeurosis of external Spermatic cord The scrotum consists of loose oblique muscle (cut) Superficial skin and an underlying Fundiform ligament of penis inguinal ring subcutaneous layer and Suspensory ligament of penis Cremaster muscle supports the testes. Transverse section of penis: Ductus (vas) deferens Corpora cavernosa penis Autonomic nerve Spongy urethra Testicular artery Corpus spongiosum penis Lymphatic vessel 28 SCROTAL SEPTUM Pampiniform plexus of testicular veins Cremaster muscle C H A P T E R Epididymis Tunica albuginea of testis External spermatic fascia Tunica vaginalis (peritoneum) DARTOS MUSCLE Internal spermatic fascia Skin of SCROTUM RAPHE Which muscles help regulate the temperature of the testes? Anterior view of scrotum and testes and transverse section of penis 1044 CHAPTER 28 THE REPRODUCTIVE SYSTEMS Figure 28.3 Internal and external anatomy of a testis. The testes are the male gonads, which produce haploid l id sperm. Sagittal Spermatic cord plane Blood vessels and nerves Ductus (vas) deferens Head of epididymis Efferent duct SEMINIFEROUS TUBULE Body of epididymis STRAIGHT TUBULE Rete testis TUNICA VAGINALIS TUNICA ALBUGINEA Ductus epididymis LOBULE SEPTUM Tail of epididymis (a) Sagittal section of testis showing seminiferous tubules SUPERIOR Spermatic cord RETE TESTIS SEMINIFEROUS Head of TUBULES Body of epididymis epididymis TUNICA VAGINALIS TESTIS TESTIS TUNICA TUNICA Tail of ALBUGINEA VAGINALIS epididymis POSTERIOR ANTERIOR (b) Lateral view of testis and associated structures (c) Sagittal section What tissue layers cover and protect the testes?  28.1 MALE REPRODUCTIVE SYSTEM 1045 A serous membrane called the tunica vaginalis (TOO-ni-ka vaj-i-NAL-is; tunica ⫽ sheath), which is derived from the perito- CLINICAL CONNECTION | Cryptorchidism neum and forms during the descent of the testes, partially covers The condition in which the testes do not descend into the the testes. A collection of serous fluid in the tunica vaginalis is scrotum is called cryptorchidism (krip-TOR-ki-dizm; crypt- called a hydrocele (HĪ -droˉ-sēl; hydro- ⫽ water; -kele ⫽ hernia). ⫽ hidden; -orchid ⫽ testis); it occurs in about 3% of full- It may be caused by injury to the testes or inflammation of the term infants and about 30% of premature infants. Untreated bi- epididymis. Usually, no treatment is required. Internal to the tu- lateral cryptorchidism results in sterility because the cells involved nica vaginalis the testis is surrounded by is a white fibrous capsule in the initial stages of spermatogenesis are destroyed by the higher composed of dense irregular connective tissue, the tunica albu- temperature of the pelvic cavity. The chance of testicular cancer is 30–50 times greater in cryptorchid testes. The testes of about 80% ginea (al⬘-buˉ-JIN-ē-a; albu- ⫽ white); it extends inward, form- of boys with cryptorchidism will descend spontaneously during the ing septa that divide the testis into a series of internal compart- first year of life. When the testes remain undescended, the condi- ments called lobules. Each of the 200–300 lobules contains one tion can be corrected surgically, ideally before 18 months of to three tightly coiled tubules, the seminiferous tubules (sem⬘-i- age. NIF-er-us; semin- ⫽ seed; -fer- ⫽ to carry), where sperm are produced. The process by which the seminiferous tubules of the testes produce sperm is called spermatogenesis (sper⬘-ma-toˉ- JEN-e-sis; genesis ⫽ to be born). The seminiferous tubules contain two types of cells: sper- cells and the release of sperm into the lumen of the seminiferous matogenic cells (sper⬘-ma-toˉ-JEN-ik), the sperm-forming cells, tubule. They also produce fluid for sperm transport, secrete the and sustentacular cells (sus⬘-ten-TAK-uˉ-lar) or Sertoli cells hormone inhibin, and regulate the effects of testosterone and (ser-TŌ-lē), which have several functions in supporting sper- FSH (follicle-stimulating hormone). matogenesis (Figure 28.4). Stem cells called spermatogonia In the spaces between adjacent seminiferous tubules are clus- (sper⬘-ma-toˉ-GŌ-nē-a; -gonia ⫽ offspring; singular is sper- ters of cells called interstitial cells or Leydig cells (LĪ-dig) (Fig- matogonium) develop from primordial germ cells (prı̄-MŌR- ure 28.4). These cells secrete testosterone, the most prevalent an- dē-al ⫽ primitive or early form) that arise from the yolk sac and drogen. An androgen is a hormone that promotes the development enter the testes during the fifth week of development. In the of masculine characteristics. Testosterone also promotes a man’s embryonic testes, the primordial germ cells differentiate into libido (sexual drive). spermatogonia, which remain dormant during childhood and ac- tively begin producing sperm at puberty. Toward the lumen of Spermatogenesis the seminiferous tubule are layers of progressively more ma- Before you read this section, please review the topic of reproduc- ture cells. In order of advancing maturity, these are primary tive cell division in Chapter 3 in Section 3.7. Pay particular atten- spermatocytes, secondary spermatocytes, spermatids, and sperm tion to Figures 3.33 and 3.34. cells. After a sperm cell, or spermatozoon (sper⬘-ma-toˉ- In humans, spermatogenesis takes 65–75 days. It begins ZŌ-on; zoon ⫽ life), has formed, it is released into the lumen of with the spermatogonia, which contain the diploid (2n) number the seminiferous tubule. (The plural terms are sperm and sper- of chromosomes (Figure 28.5). Spermatogonia are types of matozoa.) stem cells; when they undergo mitosis, some spermatogonia re- Embedded among the spermatogenic cells in the seminifer- main near the basement membrane of the seminiferous tubule ous tubules are large sustentacular cells or Sertoli cells, which in an undifferentiated state to serve as a reservoir of cells for extend from the basement membrane to the lumen of the tubule. future cell division and subsequent sperm production. The rest Internal to the basement membrane and spermatogonia, tight of the spermatogonia lose contact with the basement mem- junctions join neighboring sustentacular cells to one another. brane, squeeze through the tight junctions of the blood–testis These junctions form an obstruction known as the blood–testis barrier, undergo developmental changes, and differentiate into barrier because substances must first pass through the susten- primary spermatocytes (SPER-ma-toˉ-sı̄tz⬘). Primary sper- tacular cells before they can reach the developing sperm. By matocytes, like spermatogonia, are diploid (2n); that is, they isolating the developing gametes from the blood, the blood–tes- have 46 chromosomes. tis barrier prevents an immune response against the spermato- Shortly after it forms, each primary spermatocyte replicates 28 genic cell’s surface antigens, which are recognized as “foreign” its DNA and then meiosis begins (Figure 28.5). In meiosis I, by the immune system. The blood–testis barrier does not in- homologous pairs of chromosomes line up at the metaphase clude spermatogonia. plate, and crossing-over occurs. Then, the meiotic spindle C H A P T E R Sustentacular cells support and protect developing spermato- pulls one (duplicated) chromosome of each pair to an opposite genic cells in several ways. They nourish spermatocytes, sperma- pole of the dividing cell. The two cells formed by meiosis I tids, and sperm; phagocytize excess spermatid cytoplasm as de- are called secondary spermatocytes. Each secondary sper- velopment proceeds; and control movements of spermatogenic matocyte has 23 chromosomes, the haploid number (n). Each 1046 CHAPTER 28 THE REPRODUCTIVE SYSTEMS Figure 28.4 Microscopic anatomy of the seminiferous tubules Interstitial cell and stages of sperm production Blood capillary (spermatogenesis). Arrows indicate the SPERMATOGENIC CELLS: progression of spermatogenic cells from Basement membrane Spermatogonium (2n) least mature to most mature. The (n) and (stem cell) (2n) refer to haploid and diploid numbers of chromosomes, respectively. Sustentacular cell Primary spermatocyte (2n) nucleus Spermatogenesis occurs in the Blood–testis barrier seminiferous tubules of the testes. (tight junction) Secondary spermatocyte (n) Spermatid (n) Sperm cell or spermatozoon (n) Lumen of seminiferous tubule Which cells secrete testosterone? Transverse section of part of seminiferous tubule chromosome within a secondary spermatocyte, however, is Figure 28.5 Events in spermatogenesis. Diploid cells (2n) made up of two chromatids (two copies of the DNA) still at- have 46 chromosomes; haploid cells (n) have 23 chromosomes. tached by a centromere. No replication of DNA occurs in the secondary spermatocytes. Spermiogenesis involves the maturation of spermatids In meiosis II, the chromosomes line up in single file along the into sperm. metaphase plate, and the two chromatids of each chromosome Basement membrane separate. The four haploid cells resulting from meiosis II are of seminiferous tubule Some spermatogonia remain called spermatids (SPER-ma-tids). A single primary spermato- Superficial as precursor stem cells cyte therefore produces four spermatids via two rounds of cell SPERMATOGONIUM 2n division (meiosis I and meiosis II). 2n Mitosis A unique process occurs during spermatogenesis. As sper- Some spermatogonia matogenic cells proliferate, they fail to complete cytoplasmic pushed away from 2n separation (cytokinesis). The cells remain in contact via cyto- basement membrane plasmic bridges through their entire development (see Fig- Differentiation ures 28.4 and 28.5). This pattern of development most likely PRIMARY SPERMATOCYTE accounts for the synchronized production of sperm in any given DNA replication, area of the seminiferous tubule. It may also have survival value 2n tetrad formation, in that half of the sperm contain an X chromosome and half and crossing-over Meiosis I contain a Y chromosome. The larger X chromosome may carry MEIOSIS genes needed for spermatogenesis that are lacking on the SECONDARY SPERMATOCYTES Each smaller Y chromosome. n n chromosome has two The final stage of spermatogenesis, spermiogenesis (sper⬘- Meiosis II chromatids mē-oˉ-JEN-e-sis), is the development of haploid spermatids Cytoplasmic SPERMATIDS into sperm. No cell division occurs in spermiogenesis; each bridge spermatid becomes a single sperm cell. During this process, n n n n spherical spermatids transform into elongated, slender sperm. An acrosome (described shortly) forms atop the nucleus, which SPERMIOGENESIS SPERMATOZOA condenses and elongates, a flagellum develops, and mitochondria Deep n n n n multiply. Sustentacular cells dispose of the excess cytoplasm that sloughs off. Finally, sperm are released from their connec- tions to sustentacular cells, an event known as spermiation (sper⬘-mē-Aˉ -shun). Sperm then enter the lumen of the seminiferous tubule. Fluid secreted by sustentacular cells What is the outcome of meiosis I? Lumen of seminiferous tubule  28.1 MALE REPRODUCTIVE SYSTEM 1047 pushes sperm along their way, toward the ducts of the testes. most sperm do not survive more than 48 hours within the fe- At this point, sperm are not yet able to swim. male reproductive tract. Sperm Hormonal Control of Testicular Function Each day about 300 million sperm complete the process of Although the initiating factors are unknown, at puberty certain spermatogenesis. A sperm is about 60 ␮m long and contains hypothalamic neurosecretory cells increase their secretion of several structures that are highly adapted for reaching and pen- gonadotropin-releasing hormone (GnRH) (goˉ⬘-nad-oˉ-TRŌ- etrating a secondary oocyte (Figure 28.6). The major parts of a pin). This hormone in turn stimulates gonadotrophs in the ante- sperm are the head and the tail. The flattened, pointed head of rior pituitary to increase their secretion of the two gonadotropins, the sperm is about 4–5 ␮m long. It contains a nucleus with 23 highly luteinizing hormone (LH) (LOO-tē-in⬘-ı̄z-ing) and follicle- condensed chromosomes. Covering the anterior two-thirds of stimulating hormone (FSH). Figure 28.7 shows the hormones the nucleus is the acrosome (AK-roˉ-soˉm; acro- ⫽ atop; -some and negative feedback loops that control secretion of testoster- ⫽ body), a caplike vesicle filled with enzymes that help a sperm one and spermatogenesis. to penetrate a secondary oocyte to bring about fertilization. LH stimulates interstitial cells, which are located between Among the enzymes are hyaluronidase and proteases. The tail seminiferous tubules, to secrete the hormone testosterone (tes- of a sperm is subdivided into four parts: neck, middle piece, TOS-te-roˉn). This steroid hormone is synthesized from choles- principal piece, and end piece. The neck is the constricted re- terol in the testes and is the principal androgen. It is lipid-soluble gion just behind the head that contains centrioles. The centri- and readily diffuses out of interstitial cells into the interstitial fluid oles form the microtubules that comprise the remainder of the and then into blood. Via negative feedback, testosterone suppresses tail. The middle piece contains mitochondria arranged in a secretion of LH by anterior pituitary gonadotrophs and suppresses spiral, which provide the energy (ATP) for locomotion of sperm secretion of GnRH by hypothalamic neurosecretory cells. In some to the site of fertilization and for sperm metabolism. The prin- target cells, such as those in the external genitals and prostate, cipal piece is the longest portion of the tail, and the end piece the enzyme 5 alpha-reductase converts testosterone to another is the terminal, tapering portion of the tail. Once ejaculated, androgen called dihydrotestosterone (DHT) (dı̄-hı̄⬘-droˉ-tes- TOS-ter-oˉn). FSH acts indirectly to stimulate spermatogenesis (Figure 28.7). FSH and testosterone act synergistically on the sustentacular cells to stimulate secretion of androgen-binding protein Figure 28.6 Parts of a sperm cell. (ABP) into the lumen of the seminiferous tubules and into the About 300 million sperm mature each day. interstitial fluid around the spermatogenic cells. ABP binds to testosterone, keeping its concentration high. Testosterone stim- ulates the final steps of spermatogenesis in the seminiferous tubules. Once the degree of spermatogenesis required for male Acrosome reproductive functions has been achieved, sustentacular cells HEAD release inhibin, a protein hormone named for its role in inhibit- Nucleus ing FSH secretion by the anterior pituitary (Figure 28.7). If Neck spermatogenesis is proceeding too slowly, less inhibin is re- leased, which permits more FSH secretion and an increased rate of spermatogenesis. Mitochondria Testosterone and dihydrotestosterone both bind to the same Middle piece androgen receptors, which are found within the nuclei of target cells. The hormone–receptor complex regulates gene expression, turning some genes on and others off. Because of these changes, the androgens produce several effects: TAIL Prenatal development. Before birth, testosterone stimulates Principal the male pattern of development of reproductive system ducts 28 piece and the descent of the testes. Dihydrotestosterone stimulates development of the external genitals (described in Section C H A P T E R 28.5). Testosterone also is converted in the brain to estrogens (feminizing hormones), which may play a role in the develop- ment of certain regions of the brain in males. End piece Development of male sexual characteristics. At puberty, testosterone and dihydrotestosterone bring about develop- ment and enlargement of the male sex organs and the devel- opment of masculine secondary sexual characteristics. Sec- What are the functions of each part of a sperm cell? ondary sex characteristics are traits that distinguish males 1048 CHAPTER 28 THE REPRODUCTIVE SYSTEMS Figure 28.7 Hormonal control of spermatogenesis and and enlargement of the larynx and consequent deepening of actions of testosterone and dihydrotestosterone (DHT). In the voice. response to stimulation by FSH and testosterone, sustentacular Development of sexual function. Androgens contribute to cells secrete androgen-binding protein (ABP). Dashed red lines male sexual behavior and spermatogenesis and to sex drive (li- indicate negative feedback inhibition. bido) in both males and females. Recall that the adrenal cortex is the main source of androgens in females. Release of FSH is stimulated by GnRH and inhibited by inhibin; release of LH is stimulated by GnRH and Stimulation of anabolism. Androgens are anabolic hormones; inhibited by testosterone. that is, they stimulate protein synthesis. This effect is obvious in the heavier muscle and bone mass of most men as compared Hypothalamus to women. GnRH A negative feedback system regulates testosterone production (Figure 28.8). When testosterone concentration in the blood in- Testosterone decreases creases to a certain level, it inhibits the release of GnRH by cells release of GnRH and LH in the hypothalamus. As a result, there is less GnRH in the portal Anterior pituitary blood that flows from the hypothalamus to the anterior pituitary. Inhibin decreases Gonadotrophs in the anterior pituitary then release less LH, so Gonadotroph release of FSH the concentration of LH in systemic blood falls. With less stimu- lation by LH, the interstitial cells in the testes secrete less testos- Together with terone, and there is a return to homeostasis. If the testosterone testosterone, LH stimulates concentration in the blood falls too low, however, GnRH is again FSH stimulates FSH LH testosterone released by the hypothalamus and stimulates secretion of LH by spermatogenesis secretion the anterior pituitary. LH in turn stimulates testosterone produc- Testosterone tion by the testes. Inhibin CHECKPOINT Testosterone 1. Describe the function of the scrotum in protecting the ABP testes from temperature fluctuations. 2. Describe the internal structure of a testis. Where are sperm cells produced? What are the functions of Spermatogenic cells sustentacular cells and interstitial (Leydig) cells? Sustentacular cells Interstitial 3. Describe the principal events of spermatogenesis. secrete androgen- Dihydro- cells secrete 4. Which part of a sperm cell contains enzymes that help binding protein testosterone testosterone (DHT) the sperm cell fertilize a secondary oocyte? (ABP) 5. What are the roles of FSH, LH, testosterone, and inhibin in the male reproductive system? How is secretion of these hormones controlled? Male pattern of development (before birth) Enlargement of male sex organs Reproductive System Ducts in Males and expression of male secondary sex characteristics (starting at puberty) Ducts of the Testis Anabolism (protein synthesis) Pressure generated by the fluid secreted by sustentacular cells pushes sperm and fluid along the lumen of seminiferous tubules Key: and then into a series of very short ducts called straight tubules LH FSH Testosterone (see Figure 28.3a). The straight tubules lead to a network of ducts LH receptor FSH receptor Androgen receptor in the testis called the rete testis (RĒ-tē ⫽ network). From the rete testis, sperm move into a series of coiled efferent ducts (EF- Which cells secrete inhibin? er-ent) in the epididymis that empty into a single tube called the ductus epididymis. and females but do not have a direct role in reproduction. Epididymis These include muscular and skeletal growth that results in The epididymis (ep⬘-i-DID-i-mis; epi- ⫽ above or over; -didymis wide shoulders and narrow hips; facial and chest hair (within ⫽ testis) is a comma-shaped organ about 4 cm (1.5 in.) long hereditary limits) and more hair on other parts of the body; that lies along the posterior border of each testis (see Fig- thickening of the skin; increased sebaceous (oil) gland secretion; ure 28.3a). The plural is epididymides (ep⬘-i-di-DIM-i-dēz).  28.1 MALE REPRODUCTIVE SYSTEM 1049 Figure 28.8 Negative feedback control of blood level of Each epididymis consists mostly of the tightly coiled ductus testosterone. epididymis. The efferent ducts from the testis join the ductus epididymis at the larger, superior portion of the epididymis Gonadotrophs of the anterior pituitary produce called the head. The body is the narrow midportion of the epi- luteinizing hormone (LH). didymis, and the tail is the smaller, inferior portion. At its distal end, the tail of the epididymis continues as the ductus (vas) deferens (discussed shortly). STIMULUS The ductus epididymis would measure about 6 m (20 ft) in length if it were uncoiled. It is lined with pseudostratified colum- nar epithelium and encircled by layers of smooth muscle. The Disrupts homeostasis free surfaces of the columnar cells contain stereocilia (ster⬘-ē-oˉ- by increasing SIL-ē-a), which despite their name are long, branching microvilli (not cilia) that increase the surface area for the reabsorption of CONTROLLED CONDITION degenerated sperm. Connective tissue around the muscle layer at- Blood level of testosterone taches the loops of the ductus epididymis and carries blood ves- sels and nerves. Functionally, the epididymis is the site of sperm matura- tion, the process by which sperm acquire motility and the abil- RECEPTORS ity to fertilize an ovum. This occurs over a period of about Cells in 14 days. The epididymis also helps propel sperm into the ductus hypothalamus (vas) deferens during sexual arousal by peristaltic contraction that secrete GnRH – of its smooth muscle. In addition, the epididymis stores sperm, which remain viable here for up to several months. Any stored sperm that are not ejaculated by that time are eventually Input Decreased GnRH reabsorbed. in portal blood Ductus Deferens CONTROL CENTER Within the tail of the epididymis, the ductus epididymis be- Anterior Return to comes less convoluted, and its diameter increases. Beyond this pituitary homeostasis when point, the duct is known as the ductus deferens or vas deferens gonadotrophs response brings blood level of (DEF-er-enz) (see Figure 28.3a). The ductus deferens, which is testosterone back about 45 cm (18 in.) long, ascends along the posterior border of to normal the epididymis through the spermatic cord and then enters the Output Decreased LH pelvic cavity. There it loops over the ureter and passes over the side in systemic blood and down the posterior surface of the urinary bladder (see Fig- ure 28.1a). The dilated terminal portion of the ductus deferens is EFFECTORS the ampulla (am-PUL-la ⫽ little jar; see Figure 28.9). The Interstitial mucosa of the ductus deferens consists of pseudostratified colum- (Leydig) cells in nar epithelium and lamina propria (areolar connective tissue). testes The muscularis is composed of three layers of smooth muscle; the inner and outer layers are longitudinal, and the middle layer Secrete less is circular. testosterone Functionally, the ductus deferens conveys sperm during sexual arousal from the epididymis toward the urethra by peri- RESPONSE staltic contractions of its muscular coat. Like the epididymis, Decrease in blood the ductus deferens also can store sperm for several months. 28 level of testosterone Any stored sperm that are not ejaculated by that time are even- tually reabsorbed. C H A P T E R Spermatic Cord Which hormones inhibit secretion of FSH and LH by the The spermatic cord is a supporting structure of the male repro- anterior pituitary? ductive system that ascends out of the scrotum (see Figure 28.2). It consists of the ductus (vas) deferens as it ascends through the scrotum, the testicular artery, veins that drain the testes and carry testosterone into circulation (the pampiniform plexus), autonomic 1050 CHAPTER 28 THE REPRODUCTIVE SYSTEMS nerves, lymphatic vessels, and the cremaster muscle. The sper- (see Figure 28.2), a somewhat triangular opening in the aponeu- matic cord and ilioinguinal nerve pass through the inguinal canal rosis of the external oblique muscle. In females, the round liga- (ING-gwi-nal ⫽ groin), an oblique passageway in the anterior ment of the uterus and ilioinguinal nerve pass through the ingui- abdominal wall just superior and parallel to the medial half of the nal canal. inguinal ligament. The canal, which is about 4–5 cm (about 2 in.) The term varicocele (VAR-i-koˉ-sēl; varico- ⫽ varicose; -kele long, originates at the deep (abdominal) inguinal ring, a slitlike ⫽ hernia) refers to a swelling in the scrotum due to a dilation of opening in the aponeurosis of the transversus abdominis muscle; the veins that drain the testes. It is usually more apparent when the canal ends at the superficial (subcutaneous) inguinal ring the person is standing and typically does not require treatment. FUN CTI ON S OF ACCE SSORY SE X G L AN D SECRETIO NS Figure 28.9 Locations of several accessory reproductivee 1. The seminal vesicles secrete an enzymes that break down clotting organs in males. The prostate, urethra, and penis have been alkaline, viscous fluid that helps proteins from the seminal sectioned to show internal details. neutralize acid in the female vesicles. reproductive tract, provides 3. The bulbourethral glands The male urethra has three subdivisions: the prostatic, fructose for ATP production by secrete an alkaline fluid that membranous, and spongy (penile) urethra. sperm, contributes to sperm neutralizes the acidic motility and viability, and helps environment of the urethra and semen coagulate after mucus that lubricates the lining ejaculation. of the urethra and the tip of 2. The prostate secretes a milky, the penis during sexual slightly acidic fluid that contains intercourse. RIGHT DUCTUS (VAS) DEFERENS View Left ureter Urinary bladder Hip bone (cut) AMPULLA OF DUCTUS PROSTATE (VAS) DEFERENS SEMINAL VESICLE PROSTATIC URETHRA SEMINAL VESICLE DUCT INTERMEDIATE EJACULATORY (MEMBRANOUS) DUCT URETHRA Deep muscles of perineum CRUS OF PENIS BULBOURETHRAL (COWPER’S) GLAND BULB OF PENIS CORPORA CAVERNOSA CORPUS SPONGIOSUM PENIS PENIS SPONGY URETHRA (a) Posterior view of male accessory organs of reproduction  28.1 MALE REPRODUCTIVE SYSTEM 1051 Urinary bladder Left ureter Hip bone Pelvic diaphragm RIGHT DUCTUS (VAS) DEFERENS Obturator internus SEMINAL VESICLE muscle AMPULLA OF DUCTUS (VAS) DEFERENS PROSTATE Deep muscles of perineum Bulbospongiosus muscle (b) Posterior view of male accessory organs of reproduction What accessory sex gland contributes the majority of the seminal fluid? Ejaculatory Ducts 8. Give the locations of the three subdivisions of the male Each ejaculatory duct (ē-JAK-uˉ-la-toˉr-ē; ejacul- ⫽ to expel) is urethra. about 2 cm (1 in.) long and is formed by the union of the duct from 9. Trace the course of sperm through the system of ducts from the seminiferous tubules to the urethra. the seminal vesicle and the ampulla of the ductus (vas) deferens 10. List the structures within the spermatic cord. (Figure 28.9). The short ejaculatory ducts form just superior to the base (superior portion) of the prostate and pass inferiorly and an- teriorly through the prostate. They terminate in the prostatic ure- Accessory Sex Glands thra, where they eject sperm and seminal vesicle secretions just before the release of semen from the urethra to the exterior. The ducts of the male reproductive system store and transport sperm cells, but the accessory sex glands secrete most of the liq- Urethra uid portion of semen. The accessory sex glands include the sem- In males, the urethra (uˉ-RĒ-thra) is the shared terminal duct of the inal vesicles, the prostate, and the bulbourethral glands. reproductive and urinary systems; it serves as a passageway for both semen and urine. About 20 cm (8 in.) long, it passes through Seminal Vesicles the prostate, the deep muscles of the perineum, and the penis, and The paired seminal vesicles (VES-i-kuls) or seminal glands is subdivided into three parts (see Figures 28.1 and 26.22). The are convoluted pouchlike structures, about 5 cm (2 in.) in prostatic urethra (pros-TAT-ik) is 2–3 cm (1 in.) long and passes length, lying posterior to the base of the urinary bladder and through the prostate. As this duct continues inferiorly, it passes anterior to the rectum (Figure 28.9). Through the seminal vesi- through the deep muscles of the perineum, where it is known as the cle ducts they secrete an alkaline, viscous fluid that contains intermediate (membranous) urethra (MEM-bra-nus). The inter- fructose (a monosaccharide sugar), prostaglandins, and clotting mediate urethra is about 1 cm (0.5 in.) in length. As this duct passes proteins that are different from those in blood. The alkaline na- 28 through the corpus spongiosum of the penis, it is known as the ture of the seminal fluid helps to neutralize the acidic environ- spongy urethra, which is about 15–20 cm (6–8 in.) long. The ment of the male urethra and female reproductive tract that other- C H A P T E R spongy urethra ends at the external urethral orifice. The histol- wise would inactivate and kill sperm. The fructose is used for ogy of the male urethra may be reviewed in Section 26.8. ATP production by sperm. Prostaglandins contribute to sperm CHECKPOINT motility and viability and may stimulate smooth muscle con- 6. Which ducts transport sperm within the testes? tractions within the female reproductive tract. The clotting 7. Describe the location, structure, and functions of the proteins help semen coagulate after ejaculation. Fluid secreted ductus epididymis, ductus (vas) deferens, and ejaculatory by the seminal vesicles normally constitutes about 60% of the duct. volume of semen. 1052 CHAPTER 28 THE REPRODUCTIVE SYSTEMS Prostate provides sperm with a transportation medium, nutrients, and The prostate (PROS-taˉt; prostata ⫽ one who stands before) is a protection from the hostile acidic environment of the male’s ure- single, doughnut-shaped gland about the size of a golf ball. It thra and the female’s vagina. measures about 4 cm (1.6 in.) from side to side, about 3 cm (1.2 in.) Once ejaculated, liquid semen coagulates within 5 minutes from top to bottom, and about 2 cm (0.8 in.) from front to back. It due to the presence of clotting proteins from the seminal vesi- is inferior to the urinary bladder and surrounds the prostatic ure- cles. The functional role of semen coagulation is not known, thra (Figure 28.9). The prostate slowly increases in size from but the proteins involved are different from those that cause birth to puberty. It then expands rapidly until about age 30, after blood coagulation. After about 10 to 20 minutes, semen reliq- which time its size typically remains stable until about age 45, uefies because prostate-specific antigen (PSA) and other pro- when further enlargement may occur. teolytic enzymes produced by the prostate break down the The prostate secretes a milky, slightly acidic fluid (pH about clot. Abnormal or delayed liquefaction of clotted semen may 6.5) that contains several substances. (1) Citric acid in prostatic cause complete or partial immobilization of sperm, thereby in- fluid is used by sperm for ATP production via the Krebs cycle. hibiting their movement through the cervix of the uterus. After (2) Several proteolytic enzymes, such as prostate-specific antigen passing through the uterus and uterine tube, the sperm are af- (PSA), pepsinogen, lysozyme, amylase, and hyaluronidase, even- fected by secretions of the uterine tube in a process called ca- tually break down the clotting proteins from the seminal vesicles. pacitation (see Section 28.2). The presence of blood in semen (3) The function of the acid phosphatase secreted by the prostate is called hemospermia (hē-moˉ-SPER-mē-a; hemo- ⫽ blood; is unknown. (4) Seminalplasmin in prostatic fluid is an antibiotic -sperma ⫽ seed). In most cases, it is caused by inflammation that can destroy bacteria. Seminalplasmin may help decrease the of the blood vessels lining the seminal vesicles; it is usually number of naturally occurring bacteria in semen and in the lower treated with antibiotics. female reproductive tract. Secretions of the prostate enter the prostatic urethra through many prostatic ducts. Prostatic secre- Penis tions make up about 25% of the volume of semen and contribute The penis (⫽ tail) contains the urethra and is a passageway for to sperm motility and viability. the ejaculation of semen and the excretion of urine (Figure 28.10). It is cylindrical in shape and consists of a body, glans penis, and a Bulbourethral Glands root. The body of the penis is composed of three cylindrical The paired bulbourethral glands (bul⬘-boˉ-uˉ-RĒ-thral), or Cow- masses of tissue, each surrounded by fibrous tissue called the tu- per’s glands (KOW-pers), are about the size of peas. They are nica albuginea (Figure 28.10). The two dorsolateral masses are located inferior to the prostate on either side of the membranous called the corpora cavernosa penis (corpora ⫽ main bodies; urethra within the deep muscles of the perineum, and their ducts cavernosa ⫽ hollow). The smaller midventral mass, the corpus open into the spongy urethra (Figure 28.9). During sexual arousal, spongiosum penis, contains the spongy urethra and keeps it open the bulbourethral glands secrete an alkaline fluid into the urethra during ejaculation. Skin and a subcutaneous layer enclose all that protects the passing sperm by neutralizing acids from urine in three masses, which consist of erectile tissue. Erectile tissue is the urethra. They also secrete mucus that lubricates the end of the composed of numerous blood sinuses (vascular spaces) lined by penis and the lining of the urethra, decreasing the number of endothelial cells and surrounded by smooth muscle and elastic sperm damaged during ejaculation. Some males release a drop or connective tissue. two of this mucus upon sexual arousal and erection. The fluid The distal end of the corpus spongiosum penis is a slightly does not contain sperm cells. enlarged, acorn-shaped region called the glans penis; its mar- gin is the corona (koˉ-RŌ-na). The distal urethra enlarges within the glans penis and forms a terminal slitlike opening, Semen the external urethral orifice. Covering the glans in an uncir- Semen (⫽ seed) is a mixture of sperm and seminal fluid, a liquid cumcised penis is the loosely fitting prepuce (PRĒ-poos), or that consists of the secretions of the seminiferous tubules, seminal foreskin. vesicles, prostate, and bulbourethral glands. The volume of semen The root of the penis is the attached portion (proximal por- in a typical ejaculation is 2.5–5 milliliters (mL), with 50–150 mil- tion). It consists of the bulb of the penis, the expanded poste- lion sperm per mL. When the number falls below 20 million/mL, rior continuation of the base of the corpus spongiosum penis, the male is likely to be infertile. A very large number of sperm is and the crura of the penis (KROO-ra; singular is crus ⫽ resem- required for successful fertilization because only a tiny fraction bling a leg), the two separated and tapered portions of the cor- ever reaches the secondary oocyte. pora cavernosa penis. The bulb of the penis is attached to the Despite the slight acidity of prostatic fluid, semen has a slightly inferior surface of the deep muscles of the perineum and is alkaline pH of 7.2–7.7 due to the higher pH and larger volume of enclosed by the bulbospongiosus muscle, a muscle that aids fluid from the seminal vesicles. The prostatic secretion gives se- ejaculation. Each crus of the penis bends laterally away from men a milky appearance, and fluids from the seminal vesicles and the bulb of the penis to attach to the ischial and inferior pubic bulbourethral glands give it a sticky consistency. Seminal fluid rami and is surrounded by the ischiocavernosus muscle (see  28.1 MALE REPRODUCTIVE SYSTEM 1053 Figure 28.10 Internal structure of the penis. The inset in (b) shows details of the skin and fasciae. The penis contains the urethra, a common pathway for semen and urine. Urinary bladder Internal urethral orifice Prostatic urethra Prostate Orifice of ejaculatory duct Bulbourethral (Cowper’s) gland Intermediate urethra Deep muscles of perineum ROOT OF PENIS: Bulb of penis Crus of penis Skin Deep dorsal Superficial dorsal vein vein BODY OF PENIS: Corpora cavernosa penis Dorsal Subcutaneous layer artery Fascia Corpus spongiosum penis DORSAL Corpora cavernosa penis Spongy urethra Tunica albuginea of corpora cavernosa Deep artery of penis Corona Corpus spongiosum penis GLANS PENIS Spongy urethra Prepuce VENTRAL Tunica albuginea of (foreskin) corpus spongiosum External urethral orifice penis (a) Frontal section (b) Transverse section CLINICAL CONNECTION | Superficial dorsal vein Circumcision Deep dorsal vein Skin Circumcision (⫽ to cut around) is a Dorsal artery Subcutaneous surgical procedure in which part of or layer Corpora cavernosa penis the entire prepuce is removed. It is usually Tunica albuginea of corpora performed several days after birth, and is cavernosa penis done for social, cultural, religious, and (more Deep artery of penis rarely) medical reasons. Although most health-care professionals find no medical jus- tification for circumcision, some feel that it 28 has benefits, such as a lower risk of urinary Spongy urethra tract infections, protection against penile Corpus spongiosum penis C H A P T E R cancer, and possibly a lower risk for sexually transmitted diseases. Indeed, studies in sev- Tunica albuginea of corpus eral African villages have found lower rates spongiosum penis of HIV infection among circumcised men. (c) Transverse section Which tissue masses form the erectile tissue in the penis, and why do they become rigid during sexual arousal? 1054 CHAPTER 28 THE REPRODUCTIVE SYSTEMS Figure 11.13). The weight of the penis is supported by two ligaments that are continuous with the fascia of the penis. (1) CLINICAL CONNECTION | Premature Ejaculation The fundiform ligament (FUN-di-form) arises from the infe- A premature ejaculation is ejaculation that occurs too early, rior part of the linea alba. (2) The suspensory ligament of the for example, during foreplay or on or shortly after penetra- penis arises from the pubic symphysis. tion. It is usually caused by anxiety, other psychological Upon sexual stimulation (visual, tactile, auditory, olfactory, or causes, or an unusually sensitive foreskin or glans penis. For most imagined), parasympathetic fibers from the sacral portion of the males, premature ejaculation can be overcome by various techniques spinal cord initiate and maintain an erection, the enlargement and (such as squeezing the penis between the glans penis and shaft as stiffening of the penis. The parasympathetic fibers produce and re- ejaculation approaches), behavioral therapy, or medication. lease nitric oxide (NO). The NO causes smooth muscle in the walls of arterioles supplying erectile tissue to relax, which allows these blood vessels to dilate. This in turn causes large amounts of blood CHECKPOINT to enter the erectile tissue of the penis. NO also causes the smooth 11. Briefly explain the locations and functions of the muscle within the erectile tissue to relax, resulting in widening of seminal vesicles, the prostate, and the bulbourethral the blood sinuses. The combination of increased blood flow and (Cowper’s) glands. 12. What is semen? What is its function? widening of the blood sinuses results in an erection. Expansion of 13. Explain the physiological processes involved in erection the blood sinuses also compresses the veins that drain the penis; the and ejaculation. slowing of blood outflow helps to maintain the erection. The term priapism (PRĪ -a-pizm) refers to a persistent and usually painful erection of the penis that does not involve sexual desire or excitement. The condition may last up to several hours 28.2 Female Reproductive and is accompanied by pain and tenderness. It results from ab- normalities of blood vessels and nerves, usually in response to System medication used to produce erections in males who otherwise OBJECTIVES cannot attain them. Other causes include a spinal cord disorder, Describe the location, structure, and functions of the leukemia, sickle-cell disease, or a pelvic tumor. organs of the female reproductive system. Ejaculation (ē-jak-uˉ-LAˉ-shun; ejectus- ⫽ to throw out), the Discuss the process of oogenesis in the ovaries. powerful release of semen from the urethra to the exterior, is a The organs of the female reproductive system (Figure 28.11) sympathetic reflex coordinated by the lumbar portion of the spi- include the ovaries (female gonads); the uterine (fallopian) tubes, nal cord. As part of the reflex, the smooth muscle sphincter at or oviducts; the uterus; the vagina; and external organs, which the base of the urinary bladder closes, preventing urine from be- are collectively called the vulva, or pudendum. The mammary ing expelled during ejaculation, and semen from entering the glands are considered part of both the integumentary system and urinary bladder. Even before ejaculation occurs, peristaltic con- the female reproductive system. tractions in the epididymis, ductus (vas) deferens, seminal vesi- cles, ejaculatory ducts, and prostate propel semen into the penile portion of the urethra (spongy urethra). Typically, this leads to Ovaries emission (ē-MISH-un), the discharge of a small volume of se- The ovaries (⫽ egg receptacles), which are the female gonads, are men before ejaculation. Emission may also occur during sleep paired glands that resemble unshelled almonds in size and shape; (nocturnal emission). The musculature of the penis (bulbospon- they are homologous to the testes. (Here homologous means that giosus, ischiocavernosus, and superficial transverse perineal two organs have the same embryonic origin.) The ovaries produce muscles), which is supplied by the pudendal nerve, also con- (1) gametes, secondary oocytes that develop into mature ova (eggs) tracts at ejaculation (see Figure 11.13). after fertilization, and (2) hormones, including progesterone and Once sexual stimulation of the penis has ended, the arterioles estrogens (the female sex hormones), inhibin, and relaxin. supplying the erectile tissue of the penis constrict and the smooth The ovaries, one on either side of the uterus, descend to the muscle within erectile tissue contracts, making the blood sinuses brim of the superior portion of the pelvic cavity during the third smaller. This relieves pressure on the veins supplying the penis month of development. A series of ligaments holds them in posi- and allows the blood to drain through them. Consequently, the tion (Figure 28.12). The broad ligament of the uterus, which is a penis returns to its flaccid (relaxed) state. fold of the parietal peritoneum, attaches to the ovaries by a double-  28.2 FEMALE REPRODUCTIVE SYSTEM 1055 layered fold of peritoneum called the mesovarium (mez⬘-oˉ-VAˉ- people believed that it did. We have since learned that the cells rē-um). The ovarian ligament anchors the ovaries to the uterus, that produce ova arise from the yolk sac and migrate to the and the suspensory ligament attaches them to the pelvic wall. ovaries during embryonic development. Each ovary contains a hilum (HĪ-lum), the point of entrance and The tunica albuginea is a whitish capsule of dense irregular exit for blood vessels and nerves along which the mesovarium is connective tissue located immediately deep to the germinal attached. epithelium. The ovarian cortex is a region just deep to the tunica albu- Histology of the Ovary ginea. It consists of ovarian follicles (described shortly) sur- Each ovary consists of the following parts (Figure 28.13): rounded by dense irregular connective tissue that contains The germinal epithelium (germen ⫽ sprout or bud) is a layer collagen fibers and fibroblast-like cells called stromal cells. of simple epithelium (low cuboidal or squamous) that covers The ovarian medulla is deep to the ovarian cortex. The bor- the surface of the ovary. We now know that the term germinal der between the cortex and medulla is indistinct, but the me- epithelium in humans is not accurate because this layer does dulla consists of more loosely arranged connective tissue and not give rise to ova; the name came about because, at one time, contains blood vessels, lymphatic vessels, and nerves. FUN CTI ON S OF THE FE M AL E RE PRO DU CTIVE SYSTEM Figure 28.11 Female organs of reproduction and 1. The ovaries produce secondary development of the fetus during surrounding structures. oocytes and hormones, including pregnancy, and labor. progesterone and estrogens 4. The vagina receives the penis The organs of reproduction in females include the (female sex hormones), inhibin, during sexual intercourse and is ovaries, uterine (fallopian) tubes, uterus, vagina, vulva, and relaxin. a passageway for childbirth. and mammary glands. 2. The uterine tubes transport a 5. The mammary glands synthesize, secondary oocyte to the uterus secrete, and eject milk for and normally are the sites where nourishment of the newborn. fertilization occurs. 3. The uterus is the site of implanta- tion of a fertilized ovum, Sagittal plane Uterine tube Fimbriae Sacrum Ovary Uterus Uterosacral ligament Round ligament Posterior fornix of vagina of uterus Rectouterine pouch Cervix Vesicouterine pouch Urinary bladder Coccyx Pubic symphysis Rectum Mons pubis Clitoris 28 Vagina Urethra Labium majus C H A P T E R Anus External urethral orifice Labium minus (a) Sagittal section F I G U R E 28. 11 CONTINUES 1056 CHAPTER 28 THE REPRODUCTIVE SYSTEMS F I G U R E 28.11 CONTINUED Fimbriae Ovary Uterine tube Fundus of uterus Body of uterus Rectouterine pouch Cervix of uterus Vesicouterine pouch Urinary bladder Vagina Pubic symphysis Rectum Mons pubis Urethra Clitoris Labium minus Labium majus (b) Sagittal section Which structures in males are homologous to the ovaries, the clitoris, the paraurethral glands, and the greater vestibular glands? Figure 28.12 Relative positions of the ovaries, the uterus, and the ligaments that support them. Ligaments holding the ovaries in position are the mesovarium, the ovarian ligament, and the suspensory ligament. ANTERIOR Rectus abdominis muscle Urinary bladder View Uterus Transverse plane Round ligament Ovarian ligament Uterine (fallopian) tube Mesovarium Ovary Cecum Rectouterine pouch Broad ligament Suspensory ligament Vermiform appendix Ureter Cardinal ligament Ileum Uterosacral ligament Sigmoid colon Common iliac artery POSTERIOR Superior view of transverse section To which structures do the mesovarium, ovarian ligament, and suspensory ligament anchor the ovary?  28.2 FEMALE REPRODUCTIVE SYSTEM 1057 Figure 28.13 Histology of the ovary. The arrows indicate the sequence of developmental stages that occur as part of the maturation of an ovum during the ovarian cycle. The ovaries are the female gonads; they produce haploid oocytes. Primordial Secondary Germinal follicle f