Male Reproductive System• Consists of the testes

contained in the scrotum, the genital ducts and their associated glands (accessory glands) and the penis.

• Testes function to produce spermatozoa (sperm) and to synthesize the hormone testosterone.

• Major accessory glands include the paired seminal vesicles and the single prostate gland.

• Minor accessory glands include the two bulbourethral glands located at the root of the penis.

• Accessory glands function to manufacture the fluid portion of the semen, which transports and nourishes the spermatozoa as they pass through the excretory ducts.

• Penis is the male copulatory organ that delivers spermatozoa into the female reproductive tract and serves as a conduit for excretion of urine from the body.

Menbranous urethra

Urethra

Penis

Corpus cavernosum of the penis

Corpus cavernosum of the urethra

Prepuce Glands penis

Testicular lobuleTunicia albuginea

Tunicia vaginalis

Tubuli recti Rete testis

Bladder Prostate

Ampulla

Seminal vesticle

Ejaculatory duct

Bulbourethral gland

Ductus deferens

Ductus epididymids

Ductus efferentes

Epididymis

Mediastinumtestis

Fig 22-1 (Text)

Testes

Testis• Is an ovoid body, about 4 to 5cm long, that is

housed within the scrotum.• Develops retroperitoneally in the abdominal

cavity and descends into the scrotum,carrying parietal and visceral layers of the peritoneum (the tunica vaginalis) that partially cover the testis on its anterior and lateral surfaces.

septum

Blood vesselLumen

Seminiferous tubules

Seminiferous epithelium

Tunica vasculosaTunica

albuginea

Tunica Albuginea

• Is the thick fibrous connective tissue capsule of the testis.

• Is thickened posteriorly to form the mediastinum testis from which connective tissue septa arise to divide the organ into approximately 250 compartments (lobuli testis).

Tunica albuginea Seminiferous epithelium

Seminiferous tubules

Seminiferous Tubules

• Are the sites where spermatozoa are produced.• Are 30 to 70 cm long, with a diameter of 150 to

250 um.• Are lined by a complex, stratified epithelium.• Are enveloped by a fibrous connective tissue tunic,

composed of several layers of fibroblasts. Myoid cells, resembling smooth muscle, are present in the inner layer of some species, but not in humans.

• Form tortuous pathways through the organ before they become continuous with the short straight tubuli recti.

Seminiferous Epithelium

• Is composed of two different types of cells, the spermatogenic cells from which the germ cells eventually develop and the Sertoli cells, which support and provide nutrition to the spermatogenic cells.

• Is 4 to 8 cell layers thick.

Figure 22–4. Part of a seminiferous tubule with its surrounding tissues. The seminiferous epithelium is formed by 2 cell populations: the cells of the spermatogenic lineage and the supporting or Sertoli cells.

Cytoplasmic bridgesEarly spermatids

Secondary spermatocytes

Primary spermatocyte

Interstitial cells

spermatogonium

Late spermiogenesis

meiosis

Initial spermiogenesis

Basal lamina

fibroblast

Sertoli cell

• Tall cells with their bases resting over the basal lamina of the tubule

• The cell outline is irregular, with several infoldings.

• Cytoplasm with a reticular appearance, with lipid droplets, granules, and spindle-shaped crystalloid bodies near the nucleus (crystalloids of Charcot-Böttcher)

• Sertoli cells have tight junctions that separate the tubules into 2 compartments.

• Adluminal compartment containing the haploid spermatocytes & spermatids.

• Basal compartment containing the diploid spermatogonia.

• Prevents immune attack against sperm cells.

• Zonulae occludens join adjacent Sertoli cells & form a blood testis barrier.

Sertoli cells have multiple functions including:

• Secretion of factors which regulate spermatogenesis andSpermiogenesis- Androgen Binding Protiein( ABP)

• Secretion of inhibin which regulates hormone production

• Secretion of tubular fluid

• Phagocytosis of discarded spermatid cytoplasm

• Forms blood testis barrier

Figure 22–13. Hypophyseal control of male reproduction. Luteinizing hormone (LH) acts on the Leydig cells, and follicle-stimulating hormone (FSH) acts on the seminiferous tubules. A testicular hormone, inhibin, inhibits FSH secretion in the pituitary. ABP, androgen-binding protein. (Modified and reproduced, with permission, from Bloom W, Fawcett DW: A Textbook of Histology, 10th ed. Saunders, 1975.)

Spermatogenesis-

1) Spermatogonial Phase• refers to mitotic division of the spermatogonia to provide a

continuous supply of cells that will give rise to primary spermatocytes.

2)Meiosis• are two successive meiotic divisions that reduce the

chromosome number from diploid to haploid and produce spermatids.

3) Spermiogenesis• is cytodifferentiation and transformation of spermatids to

form spermatozoa.

Spermatogonial Phase & Meiosis

Spermiogenesis

Spermatozoa

Interstitial Cells

Interstitial Cells

INTRATESTTICULARGENITAL DUCTS

Tubuli Recti

Rete Testis

Ductuli Efferentes

Tubuli Recti

• Have a narrow lumen lined by a simple cuboidal epithelium.

• Lead into the rete testis, a network of epithelial-lined channels located in the mediastinum.

Seminiferous tubules

Tubuli recti Connective tissue

Mediastinum testis

Epithelium Rete testis

Ductuli Efferentes

• Lead from the rete testis into the epididymis.

Epithelium

Ductuli efferentes

Connective tissue

Spermatozoa

Spermatozoa

Ductuli Efferentes

EXCRETORY GENITAL DUCTS

• Ductus Epididymis• Ductus Deferens (vas deferens)

• Ampulla• Ejaculatory Duct

Menbranous urethra

Urethra

Penis

Corpus cavernosum of the penis

Corpus cavernosum of the urethra

Prepuce Glands penis

Testicular lobuleTunicia albuginea

Tunicia vaginalis

Tubuli recti Rete testis

Bladder Prostate

Ampulla

Seminal vesticle

Ejaculatory duct

Bulbourethral gland

Ductus deferens

Ductus epididymids

Ductus efferentes

Epididymis

Mediastinumtestis

Ductus Epididymis

• begins as the terminal portions of the ductuli efferentes fuse. Reservoir of spermatozoa.

• is a narrow, highly coiled tubule, 4 to 6 meters long.

• is surrounded by connective tissue containing blood vessels.

• is subdivided into a head, body, and tail region.• its lumen is lined pseudostratified columnar

epithelium.

Epithelium

• is composed of basal and principal cells.

Basal Cells

• are round and appear undifferentiated, apparently serving as precursors of the columnar principal cells.

Principle Cells

• possess stereocilia (long irregular branching microvilli) on their luminal surface.

• also possesses endoplasmic reticulum, a large Golgi complex, lysosomes, and many pinocytotic and coated vesicles in their apical portions (suggesting fluid resorption).

• secrete glycerophosphocholine, a substance that probably inhibits capacitation.

• Smooth muscle – 3 layers.

Figure 22–15. The highly coiled ductus epididymidis, sectioned several times. Its wall is made of a pseudostratified columnar epithelium surrounded by connective tissue and smooth muscle. PSH stain. Medium magnification. Inset: Higher magnification of the epithelial cells with their long microvilli (stereocilia).

microvilli

Spermatozoa

Connective tissue and smooth muscle

Basal cellColumnar cell

Ductus Deferens (vas deferens)

• begins at the end of the ductus epididymis as a straight tube with a thick muscular wall.

Pseudostratified Epithelium

• (with stereocilia) similar to that of the ductus epididymis, lines the narrow, irregular lumen of the ductus deferens.

Muscular Wall

• is composed of inner and outer layers of longitudinally oriented smooth muscle, separated from one another by a middle circular layer.

Mucosa

Inner Longitudinal smooth muscle layer

Circular smooth muscle layer

Figure 22—16. Section of the ductus deferens showing the mucosa formed by pseudostratified columnar epithelium with stereocilia and a lamina propria. The thick outer wall is formed of smooth muscle (brown) and collagen fibers (blue). Trichrome stain. Low magnification.

Outer Longitudinal smooth muscle layer

Middle circularmuscle Layer

Outer longitudional muscle layer

Inner longitudional muscle layer

Epithelium

lumen

Stereocillia

Epithelium

Seminal Vesicles

• are the paired tortuous tubular glands (15 cm in length) located adjacent the posterior aspect of the bladder.

• their ducts join the ductus deferens just prior to its entering the prostate gland.

Psuedostratified Columnar Epithelium

– lines the extensively folded mucosa of this gland.– consists of low columnar cells interspersed with

cuboidal basal cells (whose height is testosterone dependent).

Columnar Cells

– have many yellow lipochrome pigment granules and secretory granules, contain a large Golgi apparatus, many mitochondria, and an abundant rough endoplasmic reticulum.

Lamina Propria

– consists of fibroelastic connective tissue surrounded by an inner circular and an outer longitudinal layer of smooth muscle.

Adventitia– is also composed of fibroelastic connective tissue.

Secretory Product

• is a yellow, viscous fluid that is rich in fructose and other substances and constitutes about 70% of the human ejaculate.

Prostate Gland

• surrounds the urethra as it exits the urinary bladder and is the largest accessory gland.

• consist of 30 to 50 discrete branched tubuloalveolar glands that empty their contents into the prostatic urethra (via excretory ducts).

Glands of the Prostate

– are arranged in three concentric layers (central, transitional, peripheral) around the urethra and are surrounded by a fibroelastic capsule that contains smooth muscle.

– stroma from the capsule penetrate the gland and divide it into lobes.

Simple or Pseudostratified Columnar Epithelium

– lines the glands, and the fibroelastic connective tissue enveloping them contains elastic fibers and is richly vascularized.

Epithelial Cells

– contain abundant rough endoplasmic reticulum, a well-developed large Golgi complex, numerous lysosomes, and many secretory granules.

Prostatic Concretions

• composed of glycoprotein are sometimes observed in the lumina of the glands.

• may become calcified and their numbers increase with age.

Secretion

• of the prostate, under the influence of dihydrotestosterone, is a whitish, thin fluid containing proteolytic enzymes, citric acid, acid phosphatase, and lipids.

Peripheral zone

Transition zone

Central zone

Prostatic urethra

Figure 22—18. Section of prostate showing the distribution of its glands in 3 zones. The gland ducts open into the urethra.

Stroma

Smooth muscle

Blood vesselBasal cell

Prostatic concretion

Columnar cell

Penis

• functions both as an excretory organ for urine and as a copulatory organ for delivering sperm into the female reproductive tract.

• is composed of three cylindrical masses of erectile tissue. The paired corpora cavernosa lie dorsally and the single corpus spongiosum contains the penile (spongy) urethra.

• is covered by skin that overlies a loose connective tissue sheath that surrounds the corpora cavernosa and corpus spongiosum.

• skin (distally) lacks hair follicles and contains only a few sweat glands.

• hypodermis contains a prominent layer of smooth muscle but no adipose tissue.

Prepuce

• that portion of skin that covers the glans penis.• resembles as mucous membrane, since it is lined

by stratified squamous nonkeratininzed epithelium.

Tunica Albuginea

• is the thick fibrous connective tissue sheath surrounding the three erectile bodies.

• The arrangement of the dense collagen bundles in the tunica permit extensibility of the penis during erection.

Corpora Cavernosa

• are the two-paired erectile bodies dorsally in the penis.

• contain irregular vascular spaces lined by a continuous layer of endothelial cells separated from each other by trabeculae of connective tissue and smooth muscle cells.

Vascular Spaces

• are decreased in size toward the periphery of the corpora.

• become engorged with blood during erection, making the penis turgid.

Corpus Spongiosum

• is the singular erectile body surrounding the spongy urethra.

• its erectile tissue is similar to those of the corpora cavernosa, except that the trabeculae contain more elastic fibers and only a few smooth muscle cells.

• its vascular spaces are uniform throughout.

Glands of Littre

• are mucus secreting glands that are also present throughout the length of the penile urethra.

Menbranous urethra

Urethra

Penis

Corpus cavernosum of the penis

Corpus cavernosum of the urethra

Prepuce Glands penis

Testicular lobuleTunicia albuginea

Tunicia vaginalis

Tubuli recti Rete testis

Bladder Prostate

Ampulla

Seminal vesticle

Ejaculatory duct

Bulbourethral gland

Ductus deferens

Ductus epididymids

Ductus efferentes

Epididymis

Mediastinumtestis

Glans Penis

• is the terminal end of the corpus spongiosum.• contains dense connective tissue and longitudinal

muscle fibers.

Erection• occurs when the erectile tissues become distended

with blood due to parasympathetic stimulation mediated by tactile or erotic stimulation.

• Figure 22—21. Transverse section of the penis.

Glands of littre´

Erectile tissue

Blood vessel

Connective tissue

Epithelium

Urethra