45T-1, an established cell line with characteristics of Sertoli cells, forms organized aggregates in vitro after exposure to tumor necrosis factor alpha.

In the testis TNF is produced by germinal cells. The putative role of tumor necrosis factor alpha (TNF) in development and differentiation was investigated in 45T-1 mouse cell cultures, a cell line with characteristic markers of Sertoli cells, established from transgenic mouse families expressing the polyoma large T antigen in their testes. Exposure to TNF elicited a gradual assembly of the cells of the monolayer into highly organized spheroids. The first morphological sign of the changes was detected one week after TNF treatment by anti-desmin immunostaining which showed the formation of foci in the culture consisting of several hundred cells connected by an increasing number of cell contacts. Between days 10-20 the cells formed large ovoid or vermiform aggregates covered by several layers of flat, elongated cells. These cells extended septae into the inner mass of the spheroids consisting of loosely arranged, large polygonal or palisadic cells. The spheroids were surrounded by radially arranged elongated cells covered by small blebs. TNF treatment upregulated laminin expression in 45T-1 cell cultures, which is known to induce formation of cord-like structures by Sertoli cells in vitro. Coculturing 45T-1 cells with immortalized germinal cells or TNF-producing HeLa cells also lead to the formation of spheroids. These observations suggest that TNF production of germinal cells might contribute to the organization/differentiation of Sertoli cells.