•Each seminal vesicle, a long, narrow gland that is highly folded on itself, produces a rich, nutritive substance with a characteristic yellow color that supplies a fructose-rich secretion for the spermatozoa.

•The prostate gland is composed of numerous individual glands that surround, and whose ducts pierce, the wall of the urethra. These glands are distributed in three regions of the prostate and are therefore categorized as mucosal, submucosal, and external (main) prostatic glands.

The secretion of the prostate gland is a whitish, thin fluid containing fibrinolysin, citric acid, serine protease (prostate-specific antigen, PSA), and acid phosphatase.

Prostatic concretions are frequently found in the lumina of the prostate gland.

PENIS

The penis, the male organ of copulation, is normally in the flaccid state. During erotic stimulation, however, its three cylindrical bodies of erectile tissues become distended with blood. The fluid turgid pressure within the vascular spaces of the erectile tissues greatly enlarges the penis, causing it to become erect and hard. Subsequent to ejaculation or the termination of erotic stimulation, detumescence follows and the penis returns to its flaccid state.

Erection and Ejaculation

The penis, during copulation, delivers spermatozoa-con- taining semen to the female reproductive tract. It is also the excretory organ for urine. The penis is covered by skin and is composed of three erectile bodies, the two corpora cavernosa and the ventrally positioned corpus spongiosum (urethrae).

M A L E R E P R O D U C T I V E S Y S T E M 437

•Each erectile body, housing large, endothelially lined cavernous spaces, is surrounded by a thick connective tissue capsule, the tunica albuginea.

The erectile bodies are supplied by helicine arteries that are usually bypassed via arteriovenous shunts, maintaining the penis in a flaccid state.

Parasympathetic impulses to these shunts cause vasoconstriction, directing blood into the helicine arteries and thus into the cavernous spaces.

The erectile bodies (especially the corpora cavernosa) become engorged with blood, and the penis becomes erect.

Subsequent to ejaculation or in the absence of continued stimulation, parasympathetic stimulation ceases; blood flow to the helicine arteries is diminished; blood slowly leaves the cavernous spaces; and the penis returns to its flaccid condition.

•Ejaculation is the forceful expulsion of semen from the male reproductive tract.

The force required for ejaculation is derived from rhythmic contraction of the thick smooth muscle layers of the ductus (vas) deferens and the rapid contraction of the bulbospongiosus muscle.

•Each ejaculate contains spermatozoa suspended in seminal fluid.

•The accessory glands of the male reproductive system, the prostate and bulbourethral glands, as well as the seminal vesicles (and even the glands of Littré) contribute to the formation of the fluid portion of semen.

•Secretions of the bulbourethral glands lubricate the

urethra, whereas secretions of the prostate assist the spermatozoa in achieving motility by neutralizing the acidic secretions of the ductus deferens and of the female reproductive tract.

•Approximately 70% of the fluid portion of the semen is due to the secretions of the seminal vesicles.

This figure is from the testis of a postpubertal patient demonstrating the absence of spermatogenesis in the seminiferous tubule as well as a very thick, hyalinized basement membrane. (Reprinted with permission from Rubin R, Strayer D, et al., eds. Rubin’s Pathology. Clinicopathologic Foundations of Medicine, 5th ed., Baltimore: Lippincott Williams & Wilkins, 2008, p. 763.)

Vasectomy

Vasectomy is a method of sterilization that is performed by making a small slit in the wall of the scrotum through which the ductus deferens is severed.

A normal ejaculate averages about 3 mL of semen that contains 60 to 100 million spermatozoa per mL. It is interesting to note that about 20% of the ejaculated spermatozoa are abnormal and 25% immotile. An individual producing less than 20 million spermatozoa per milliliter of ejaculate is considered sterile.

Benign Prostatic Hypertrophy

The prostate gland undergoes hypertrophy with age, resulting in benign prostatic hypertrophy, a condition that may constrict the urethral lumen resulting in difficulty in urination. At age 50, about 40% of the male population is affected, and at age 80, about 95% of the male population is affected by this condition.

This photomicrograph is from a patient with nodular hyperplasia of the prostate. Observe that the gland is displaying cellular hypertrophy of the epithelium whose folding, in places, partially occludes its lumen. (Reprinted with permission from Rubin R, Strayer, D, et al., eds. Rubin’s Pathology. Clinicopathologic Foundations of Medicine, 5th ed., Baltimore: Lippincott Williams & Wilkins, 2008, p. 774.)

Adenocarcinoma of the Prostate

Adenocarcinoma of the prostate affects about 30% of the male population over 75 years of age. Although this carcinoma is slow growing, it may metastasize to the bone. Analysis of elevated levels of prostate-specific antigen (PSA) in the bloodstream is utilized as an early diagnostic test for prostatic cancer. Biopsy is required for accurate diagnosis.

Testicular Cancer

Testicular cancer affects mostly men younger than 40 years of age. It is discovered on palpation as a lump in the scrotum. If the lump is not associated with the testis, it is usually benign, whereas if it is associated with the testis it is usually malignant; therefore, a lump noticed on the testis, whether or not it is painful, should be examined by a physician. Frequently, individuals with testicular cancer present with elevated blood alpha-fetoprotein and human chorionic gonadotropin levels.

This figure is from the testis of a patient with a form of a testicular cancer known as seminoma. Observe the clusters of tumor cells with large nuclei. These cells are enveloped by a connective tissue septum that appears quite cellular due to the lymphocytic infiltration. (Reprinted with permission from Rubin, R, Strayer, D, et al., eds. Rubin’s Pathology. Clinicopathologic Foundations of Medicine, 5th ed., Baltimore: Lippincott Williams & Wilkins, 2008, p. 769.)

Balanoposthitis

Accumulation of a thick, yellowish-white exudate underneath the foreskin of uncircumcised men can be a breeding ground for yeast and bacteria that, if not cleaned, may cause inflammation of the foreskin, known as posthitis, as well as inflammation of the glans penis, known as balanitis. When the two occur together, the condition is known as balanoposthitis. The condition may be accompanied by redness, pain, and itching as well as a swelling of the glans with a concomitant stricture of the urethra.

Phimosis

Phimosis, a tight foreskin that cannot easily be pulled over the glans penis, is a normal condition in uncircumcised infants, but in mature men, the condition can be very painful and may result in interference with urination and sexual activity. As the penis becomes erect, the foreskin cannot expand to accommodate the increase girth and may result in balanoposthitis and urinary tract infections. Circumcision can usually alleviate this condition.

System Reproductive Male • 1-18 GRAPHIC

M A L E R E P R O D U C T I V E S Y S T E M 441

Neck

Head

Outer dense fibers

Spermiogenesis• 2-18 GRAPHIC

estis • T1-18 PLATE

442 M A L E R E P R O D U C T I V E S Y S T E M

FIGURE 1. Testis. Monkey. Plastic section. ×14.

This low magnification photomicrograph of the testis displays its thick tunica albuginea (TA) as well as the slender septa (Se) that attach to it. Observe that sections of seminiferous tubules (ST) present various geometric profiles, attesting to their highly convoluted form. Note that each lobule (Lo) is densely packed with seminiferous tubules, and the connective tissue stroma (arrows) occupies the remaining space. A region similar to the boxed area is presented at a higher magnification in Figure 2.

FIGURE 3. Testis. Seminiferous tubule. Monkey. Plastic section. ×540.

The adjacent walls of two seminiferous tubules (ST), in close proximity to each other, are composed of myoid cells (MC), fibroblasts (F), and fibromuscular connective tissue (CT). The stratified seminiferous epithelium (SE) is separated from the tubular wall by a basal membrane (arrowheads). Spermatogonia (Sg) and Sertoli cells (SC) lie on the basal membrane and are in the basal compartment (BC), whereas primary spermatocytes (PS), secondary spermatocytes, spermatids (Sp), and spermatozoa (Sz) are in the adluminal compartment (AC). Observe that the lumen

(L) of the seminiferous tubule contains spermatozoa as well as cellular debris discarded during the transformation of spermatids into spermatozoa. Compare the cells of the seminiferous epithelium with those of Figure 4.

FIGURE 2. Testis. Seminiferous tubules. Monkey. Plastic section. ×132.

This photomicrograph is a higher magnification of a region similar to the boxed area of Figure 1. Observe that the tunica vasculosa (TV) of the tunica albuginea (TA) is a highly vascular region (arrows) and that blood vessels (BV) penetrate the lobuli testis in connective tissue septa (Se). The walls of the seminiferous tubules (ST) are closely apposed to each other (arrowheads), although in certain regions the cellular stroma (St) is evident. Observe that the lumen (L) of the seminiferous tubule is lined by a stratified seminiferous epithelium (SE).

FIGURE 4. Testis. Seminiferous tubule. Monkey. Plastic section. ×540.

Observe that the fibromuscular walls of the two tubular cross sections are very close to each other (arrows); however, in regions, arterioles (A) and venules (V) are evident. The Sertoli cells (SC) may be recognized by their pale nuclei and dense nucleoli (n). In comparing the seminiferous epithelia (SE) of the tubules in the right and left halves of this photomicrograph, as well as those of Figure 3, it should be noted that their cellular compositions are different, indicative of the cyclic stages of the seminiferous epithelium. Note also that three types of spermatogonia are recognizable by their nuclear characteristics: dark spermatogonia A (Ad) possessing dark, flattened nuclei; pale spermatogonia A (Ap) with flattened pale nuclei; and spermatogonia B (B) with round nuclei.

Testis

Epididymis

Seminiferous tubule

Testis, epididymis, and seminiferous tubule

ST

Sg

CT

MC

F

TA

TV

BV

L

Se

SE

ST

L

St

FIGURE 1 FIGURE 2

estis • T1-18 PLATE

Epididymis and estis • T2-18 PLATE

444 M A L E R E P R O D U C T I V E S Y S T E M

FIGURE 1. Interstitial cells. Testis. Monkey. Plastic section. ×270.

The stroma (St) surrounding seminiferous tubules (ST) possesses a rich vascular supply (BV) as well as extensive lymphatic drainage (LV). Much of the vascular elements are associated with the endocrine cells of the testis, the interstitial cells of Leydig (IC), which produce testosterone. Inset. Interstitial cells. Testis. Monkey. Plastic section. ×540. The interstitial cells (IC), located in small clumps, are recognizable by their round-to-oval nuclei (N) and the presence of lipid (arrow) within their cytoplasm.

FIGURE 3. Ductuli efferentes. Human. Paraffin section. ×132.

The first part of the epididymis, the ductuli efferentes (De), receives spermatozoa (Sz) from the rete testis. The lumina of the ductuli are lined by a simple columnar epithelium (Ep), composed of tall and short cells, which are responsible for the characteristic fluted (uneven) appearance of these tubules. The thick fibroelastic connective tissue (CT) wall of the ductuli houses numerous smooth muscle cells (SM).

FIGURE 2. Rete testis. Human. Paraffin section. ×132.

The rete testis (RT), located in the mediastinum testis (MT), is composed of labyrinthine, anastomosing spaces lined by a simple cuboidal epithelium (Ep). The dense collagenous connective tissue (CT) of the mediastinum testis is evident, as are the profiles of seminiferous tubules (ST). Spermatozoa gain access to the rete testis via the short, straight tubuli recti (TR).

FIGURE 4. Ductus epididymis. Monkey. Plastic section. ×132.

The ductus epididymis (DE) may be distinguished from the ductuli efferentes with relative ease. Note that the nuclei (N) of the pseudostratified epithelial lining (Ep) are of two types, oval and round, whereas those of the ductuli are round. Observe that the lumen contains numerous spermatozoa (Sz) and that the epithelium sits on a basal lamina. The connective tissue wall of the ductus epididymis may be differentiated easily from its circularly arranged smooth muscle coat (SM).

Ep

RT

MT

ST St

LV BV

ST

N

DE

Ep

SM

Sz

Sz

Epididymis and estis • T2-18 PLATE

Vesicle Seminal and Deferens, Ductus , Epididymis• 3-18 PLATE

CT

SM

n

PC

MM

CT

Ep

FIGURE 3

L

Ep

BV LP

IL

MC

OL

FIGURE 2

C

Sz

L

CC

N

BC

FIGURE 4

Vesicle Seminal and Deferens, Ductus , Epididymis• 3-18 PLATE

Urethra and Penis, ostate, • Pr4-18 PLATE

448 M A L E R E P R O D U C T I V E S Y S T E M

FIGURE 1. Prostate gland. Monkey. Plastic section. ×132.

The prostate gland, the largest of the male reproductive accessory glands, possesses a thick fibroelastic connective tissue capsule with which the connective tissue stroma (St) is continuous. Note that the stroma houses smooth muscle (SM) and blood vessels. The secretory portion of the prostate gland is composed of individual glands of varied shapes but consisting of a simple cuboi- dal-to-low columnar type of epithelium (Ep), although regions of pseudostratified columnar epithelia are readily apparent. A region similar to the boxed area is presented at a higher magnification in Figure 2.

FIGURE 3. Penis. Human. x.s. Paraffin section. ×14.

The penis is composed of three erectile bodies: the two corpora cavernosa and the corpus spongiosum. The cross section of the corpus spongiosum (CS) displays the urethra (U), which is surrounded by erectile tissue (ET), whose irregular, endothelially lined cavernous spaces (Cs) contain blood. The spongy tissue is surrounded by the thick, fibrous tunica albuginea (TA). The three cavernous bodies are surrounded by a looser connective tissue sheath to which the skin (removed here) is attached. The boxed area is presented at a higher magnification in Figure 4. Inset.

Penis. Human. x.s. Paraffin section. ×14. The cavernous spaces

(Cs) of the corpus cavernosum are larger than those of the corpus spongiosum. Moreover, the fibrous trabeculae (FT) are thinner, resulting in the corpora cavernosa becoming more turgid during erection than the corpus spongiosum.

FIGURE 2. Prostate gland. Monkey. Plastic section. ×540.

This photomicrograph is a higher magnification of a region similar to the boxed area of the previous figure. Observe that the fibroelastic connective tissue stroma (St) presents numerous blood vessels (BV) and smooth muscle cells (SM). The parenchyma of the gland is composed of columnar cells (CC) as well as short basal cells (BC). Note that the dome-shaped apices (arrows) of some of the columnar cells appear to protrude into the lumen, which contain a prostatic concretion (Pc). The number of these concretions, which may calcify, increases with age.

FIGURE 4. Urethra. Human. Paraffin section. ×132.

This photomicrograph is a higher magnification of the boxed area of the previous figure. Note that the spongy urethra (U) is lined by a pseudostratified columnar epithelium (Ep) surrounded by a loose connective tissue sheath (CT), housing a rich vascular supply (BV). The entire urethra is enveloped by the erectile tissue (ET) of the corpus spongiosum. Additionally, the mucous glands of Littré (GL) deliver their secretory product into the lumen of the urethra, lubricating its epithelial lining.

St SM

St

BV

Ep

Pc

Urethra and Penis, ostate, • Pr4-18 PLATE

FIGURE 1. Epididymis. Rabbit. Electron microscopy. ×7,200.

The epithelial lining of the rabbit ductuli efferentes is composed of two types of tall columnar cells: principal cells (PC) and

ciliated cells (CC). Note that both cell types possess numerous organelles, such as Golgi (G), mitochondria (m), and rough endoplasmic reticulum (arrows). Additionally, principal cells contain dense bodies (DB), probably a secretory material. (Courtesy of Dr. R. Jones.)