Special Histology and Embryology: Practical Course - V. K. Napkhanyuk 2001

Reproductive System
Male Reproductive System
Ductus Deferentes

The Ductus deferens form a system of tubules within the Testis and its Epididymis through which sperm is transported to the Urethra. The excretory ducts begin as the straight testicular tubules (tubuli seminiferi recti), which empty into the rete testis located in the Mediastinum. From this network, 12–15 convoluted efferent ductules (ductuli efferentes testis) emerge and connect to the duct of the epididymis. The latter coils extensively to form the body of the epididymis and, in its lower tail region, transitions directly into the ductus deferens, which reaches the Prostate Gland and opens into the urethra.

The ductus deferens is a paired organ. It is a tube approximately 45 cm in length with a lumen of 0.2–0.5 mm.

Its wall consists of three layers: 1) a mucous membrane (mucosa) lined with Cytology/practical/33.html">Pseudostratified columnar epithelium; 2) a muscular layer (muscularis) composed of three layers of smooth myocytes: inner and outer longitudinal layers, and a middle circular layer; and 3) an adventitial layer formed of loose Connective Tissue that gradually merges into the surrounding Tissues of the Spermatic Cord.

The ejaculatory duct (ductus ejaculatorius) is a paired segment of the sperm-conducting pathways, located distal to the junction of the ductus deferens and Seminal Vesicles. It passes through the prostate gland and opens into the urethra.

Its wall consists of three layers: 1) a mucous membrane that forms numerous folds and is composed of a bilayered epithelium of tall columnar bordered Cells and low basal cells; 2) a muscular layer characterized by a weaker development of muscular elements compared to the ductus deferens; and 3) an adventitial layer formed of connective tissue that fuses with the stroma of the prostate.

Slides for Study

Slide 1. Testis with Epididymis (Fig. 70).

Low magnification. Examine and make a drawing of the slide. Identify the fibrous capsule (tunica albuginea) covered by a serous membrane, locate the epididymis, and find at least one major septum possessing the same Structure as the capsule, along with Blood Vessels running along it. Observe the cross-sections of the convoluted seminiferous tubules, which make up the bulk of the testis, and the interstitial connective tissue located between them, containing blood vessels, nerves, and large interstitial (Leydig) cells.

Lumina are visible in vertically sectioned tubules, whereas tangential sections do not show lumina. Each tubule is surrounded by its own connective tissue sheath, inside of which, resting on a basement membrane, lies the spermatogenic epithelium consisting of several rows of Germ Cells at various Selection/3.html">Stages of development.

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Fig. 70. Testis with epididymis. Hematoxylin-eosin staining. x 100:

1 — testis; 2 — epididymis; 3 — tunica albuginea; 4 — convoluted seminiferous tubules; 5 — spermatogenic epithelium; 6 — proper Sheath of the convoluted tubule; 7 — supporting cells, or sustentocytes (Sertoli cells); 8 — interstitial cells, or glandulocytes (Leydig cells); 9 — efferent ductule of the testis; 10 — duct of the epididymis; 11 — spermatozoa; 12 — fat cells; 13 — blood vessels

Numerous cross-sections of tubules surrounded by connective tissue containing blood vessels are visible within the epididymis. Two groups of tubules, separated by a layer of connective tissue, can be distinguished: narrower ones with an uneven lumen contour, and wider ones with a broad and smooth lumen. The former represent the efferent ductules of the HEAD of the epididymis. They are surrounded by a dense Proper Connective Tissue sheath containing smooth Muscle, upon which rests an epithelium composed of tall columnar cells. These cells transition into low cuboidal cells. The other tubules are multiple cross-sections of the highly convoluted duct of the epididymis (Fig. 71). The epithelium of this duct is represented by tall columnar cells whose nuclei are located near the base.

Fig. 71. Spermatogenesis and STRUCTURE OF THE convoluted tubule wall (diagram):

1 — supporting Cell, or sustentocyte (Sertoli cell); spermatogonia; 2 — primary spermatocytes; 3 — secondary spermatocytes; 4 — spermatids; 5 — successive stages of spermiogenesis; 6 — spermatozoa; 7 — basement membrane of the epithelial-spermatogenic layer; 8 — basal layer; 9 — blood vessels; 10 — myoid layer

High magnification. It can be seen that the proper sheath of the convoluted seminiferous tubules consists of Fibrous connective tissue with a small number of fibrocytes possessing elongated-oval nuclei. The spermatogenic epithelium is separated from the proper sheath by a basement membrane. The Cells of the spermatogenic epithelium are embedded in a gelatinous mass—the Sertoli syncytium. Within this syncytium, perinuclear regions known as Sertoli cells can be distinguished. By examining various tubules, one can trace The process of transformation of spermatids into spermatozoa.

Label on the figure: 1) epididymis; 2) tunica albuginea; 3) convoluted seminiferous tubules; 4) spermatogenic epithelium; 5) proper sheath of the convoluted tubule; 6) supporting cells; 7) interstitial cells (Leydig cells); 8) efferent ductule of the testis; 9) duct of the epididymis; 10) spermatozoa; 11) fat cells; 12) blood vessels.

Slide 2. Cross-section of the human spermatic cord (Fig. 72).

Fig. 72. Cross-section of the human spermatic cord. Hematoxylin-eosin staining. x 40:

1 — pseudostratified epithelium of the mucosa; 2 — lamina propria of the mucosa; 3 — inner longitudinal layer of the muscular coat; 4 — middle circular layer of the muscular coat; 5 — outer longitudinal layer of the muscular coat; 6 — adventitial layer; 7 — blood vessels; 8 — nerve fiber bundles

Low magnification. Study and make a drawing of the slide. The spermatic cord comprises the ductus deferens, numerous blood vessels, and nerves. The wall of the ductus deferens is very thick. It is formed by three coats: mucosal, muscular, and adventitial. The lumen of the duct is star-shaped because the mucosa forms longitudinal folds. The epithelium of the mucosa is pseudostratified columnar. The muscular coat is also very thick, consisting of three layers of Smooth Muscle tissue: inner and outer longitudinal layers, and a middle circular layer. The adventitia is formed of loose connective tissue.

Label on the figure: 1) ductus deferens: a) mucosa, folds, pseudostratified columnar epithelium; b) muscular coat — inner longitudinal layer, middle circular layer, outer longitudinal layer; c) adventitia; 2) blood vessels: a) Arteries; b) Veins; 3) nerve trunks.