Ultrastructure of peritubular tissue in association with tubular hyalinization in human testis

Testicular peritubular tissue, also known as the tunica propria, surrounds the seminiferous tubules and is responsible for contractile, paracrine and transport functions. The aim of the present report is to describe the pathomorphology of peritubular tissue in association with tubular hyalinization in human testis. Twenty-seven testicular biopsies from 21 subfertile and infertile men were studied with the electron microscope. Biopsies from five patients showed complete or nearly complete tubular hyalinization, In addition to changes described earlier, the following new ultrastructural features were observed. 1. loss of polarity and configuration of myoid cells; 2. protrusion of myoid cells towards the tubule and evagination of basal lamina surrounding the tubule towards the interstitial direction leading to 'bridge' formation. These 'bridges' of myoid cells often created completely separated small compartments within the tunica propria; 3. vacuolization and fragmentation of myoid cell nuclei; 4. a balloon-like swelling of myoid cell containing phagolysosomes and lipid droplets. We conclude that disorganization and loss of vital functions of the extracellular matrix and myoid cells contribute to the pathogenesis of tubular hyalinization.