S excurrent duct system

The excurrent duct system develops from the mesonephric (Wolffian) duct and mesonephric tubules

The initial development of Leydig cells and initiation of testosterone secretion stimulate the mesonephric (Wolffian) duct to differentiate into the excretory duct system for the developing testis (Fig. 21.20). The portion of the mesonephric duct adjacent to the developing testis becomes convoluted and differentiates into the duct of the epididymis. In addition, a number (about 20) of the remaining mesonephric tubules in this region make contact with the developing seminiferous cords and finally develop into the efferent ductules (Fig. 21.21). They connect the developing rete testis with the duct of the epididymis. The distal part of the mesonephric duct acquires a thick, smooth muscle coat and becomes the ductus deferens. The end of the distal mesonephric duct gives rise to the ejacu-latoiy duct and seminal vesicles.

The efferent ductules are lined with pseudostratified columnar epithelium

In man, approximately 20 efferent ductules connect the channels of the rete testis at the superior end of the mediastinum to the proximal portion of the duct of the epididymis. As the efferent ductules exit the testis, they become highly coiled and form 6 to 10 conical masses, the coni vasculosi, whose bases form part of the head of the epididymis. The coni vasculosi, each about 10 mm in length, contain the highly convoluted ducts that measure 15 to 20 cm in length. At the base of the cones, the efferent ducts open into a single channel, the duct of the epididymis (see Fig. 21.4).

mesonephric tubules, __

mesonephric duct rete testis mesonephric duct

seminiferous tubule tunica albugĂ­nea primordium of prostate

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