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J Androl. 2004 May-Jun;25(3):417-25.

The contractile wall of the caput epididymidis in men affected by congenital or postinflammatory obstructive azoospermia.

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Andrology Unit, Department of Internal Medicine, University of L'Aquila (I), Milano, Italy.


The transport and storage of spermatozoa in the epididymis depend on the contractile activity of its tubular wall. It is not known what differences exist in the contractile wall of the human epididymis in cases of obstructive azoospermia. The contractile wall in the tubules of the caput epididymidis was analyzed by light microscopy and transmission electron microscopy in 10 azoospermic men, 5 with a bilateral congenital absence of vas deferens (CBAVD) and 5 with a bilateral postinflammatory congestive obstruction of the epididymis. Five specimens from the same region of the caput epididymidis, obtained from fertile men who had undergone an orchidectomy because of testicular cancer, served as controls. No differences were observed between congenital and congestive obstructions. The contractile wall in caput tubules proximal to the obstructed level was strongly thickened when compared with controls (62.98 +/- 5.84 micro; 80.82 +/- 7.72 micro vs 19.59 +/- 2.23 micro, respectively, for congestive and congenital obstructions vs controls; P <.0001 vs controls), and the spindle-shaped myoid cells, which formed the contractile wall in normal cases, were replaced by large smooth muscle cells (SMCs) that showed features of coexisting contractile and secretory functions. The former included crowded cytoplasmic bundles of thin myofilaments (5-6 nm in diameter) converging to a large number of dense bodies, numerous micropinocytotic vesicles of the plasma membrane, and a continuous cell basement membrane. The presence of a developed rough endoplasmic reticulum and a Golgi complex, associated with the accumulation of thick layers of pericellular basement membrane-like material and ground substance, was indicative of a secretory phenotype of SMCs. The increased mechanical forces on the epididymal wall upstream from the obstruction might eventually activate the differentiation of myoid cells into SMCs, leading to an altered physiology of the contractile wall that could have possible clinical relevance in the case of microsurgical epididymovasostomy.

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