FIGURE 22.20 • Schematic diagram of development of intratesticular and excurrent duct systems. a. This diagram shows the testis in the seventh week of development before it descends into the scrotal sac. Note that the mesonephric duct and its tubules give rise to the excurrent duct system for the developing testis. b. Sagittal section of a fully developed testis positioned within the scrotum. Note that the seminal vesicles, ejaculatory ducts, ductus deferens, epididymis, and efferent ductules are all developed from the mesonephric duct and tubules. The seminiferous tubules, straight tubules, and rete testis develop from the indifferent gonads. The prostate gland develops from the prostatic primordium that originates from the pelvic urethra.
FIGURE 22.21 • Photomicrograph of efferent ductules. The specimen in this photomicrograph was stained with picric acid and hematoxylin to better visualize the epithelial components of the efferent ductules. The efferent ductules are lined by pseudostratified columnar epithelium. The luminal surface has an uneven or wavy appearance because of the presence of alternating groups of tall columnar cells and cuboidal cells. The ductules are surrounded by several layers of circularly arranged smooth muscle (SM). Within the ductule lumina are clumped spermatozoa (asterisks). Connective tissue (CT ) makes up the stroma of the organ and contains blood vessels (BV ) of various sizes. 120. Inset. This higher magnification of the pseudostratified epithelium shows columnar and cuboidal cells that contain sparse cilia. 500.
FIGURE 22.22 • Photomicrograph of human epididymis. This photomicrograph of an H&E–stained section shows the highly coiled ductus epididymis. Its coiled nature is reflected in the variously shaped profiles of the duct. Within the connective tissue are numerous profiles of blood vessels (BV ). The vessels tend to follow the duct; thus they too reflect multiple profiles of several vessels. The section of the duct within the rectangle is shown at higher magnification in Figure 22.23. 30.
The ductus deferens is the longest part of the excurrent duct system.
The ductus deferens (vas deferens) is a direct continuation of the tail of the epididymis (see Fig. 22.1). It ascends along the posterior border of the testis, close to the testicular vessels and nerves. It then enters the abdomen as a component of the spermatic cord, by passing through the inguinal canal. The spermatic cord contains all of the structures that pass to and from the testis. In addition to the ductus deferens, the spermatic cord contains the testicular artery, small arteries to the ductus deferens and cremaster muscle, the pampiniform plexus, lymphatic vessels, sympathetic nerve fibers, and the genital branch of the genitofemoral nerve. All of these structures are surrounded by fascial coverings derived from the anterior abdominal wall. After leaving the spermatic cord, the ductus deferens descends in the pelvis to the level of the bladder, where its distal end enlarges to form the ampulla of ductus deferens. The ampulla is joined there by the duct of the seminal