Extracellular matrix promotes rat Sertoli cell histotypic expression in vitro.

We describe procedures for the preparation of a cell-free seminiferous tubule biomatrix, and provide evidence demonstrating that this material constitutes a useful substratum for maintaining the normal architecture of Sertoli cells in primary culture. Seminiferous tubule biomatrix, which has the morphological appearance of a fibrillar network rich in filaments and amorphous substance, is shown to consist of about 50% protein, most of which is collagen and glycoproteins. Fibronectin and laminin are also present in the seminiferous tubule biomatrix, as judged by immunofluorescence microscopy. Sertoli cell aggregates plated on this substratum retain a cuboidal to columnar shape, spread very slowly to form a monolayer, and survive for at least 3 weeks when cultured in a hormone-free, serum-free, chemically defined medium. In contrast, Sertoli cells plated onto uncoated polystyrene readily spread to form a monolayer of flat squamous cells which do not survive as well. Other morphological and ultrastructural characteristics are described which indicate that cells cultured on the seminiferous tubule biomatrix more closely resemble those of Sertoli cells in vivo than do cells plated on uncoated plastic. These differences in cell structure, including the maintenance of normal polarity as indicated by the presence of basolateral tight junctional complexes, remain evident for periods of 10 to 14 days after plating Sertoli cells onto biomatrix substratum. Rates of DNA synthesis by immature Sertoli cells plated onto biomatrix are less than rates by cells plated onto uncoated plastic. The data are discussed in relation to the role of substratum in the preservation of normal functions and histotype of Sertoli cells.