Laminin, type IV collagen, and fibronectin in normal and cryptorchid human testes. An immunohistochemical study.

An immunohistochemical study of laminin, type IV collagen, and fibronectin was carried out in the testes of normal men and in the cryptorchid and contralateral scrotal testes of cryptorchid men from 2 to 40 years of age. The integrated optical density (IOD) per unit area of the lamina propria was measured in the immunostained sections. Fibronectin was found throughout the thickness of the lamina propria of the seminiferous tubules and in the interstitial connective tissue. No differences between normal and cryptorchid testes were found. Laminin was observed in the innermost part of the lamina propria of the seminiferous tubules and surrounding the endothelium of blood capillaries from infancy. No differences were found between normal and cryptorchid testes in the prepubertal period. In adult cryptorchid testes, laminin formed more numerous and deeper invaginations towards the seminiferous epithelium than in normal adult testes. Type IV collagen appeared throughout the thickness of the lamina propria of normal testes as well as in the wall of interstitial blood vessels. From infancy, the lamina propria of seminiferous tubules, but not blood vessel walls, showed lesser immunostaining for type IV collagen and a lower IOD of this component than did control tests from men of the same age. No differences between unilateral and bilateral cryptorchidism were found. The contralateral scrotal testes of cryptorchid males showed intermediate immunostaining for type IV collagen between that of normal control testes and that of cryptorchid testes. These findings suggest that the lamina propria of seminiferous tubules is lesioned at an early age in both cryptorchid and contralateral scrotal testes of cryptorchid men.