Zur funktionellen Morphologie des Rete testis, der Tubuli recti und der Terminalsegmente der Tubuli seminiferi des geschlechtsreif en Rindes1,2

The functional morphology of the rete testis, tubuli recti and terminal segments of the tubuli seminiferi in the mature bull The terminal portion of the seminiferous tubule in the mature bull has three segments: a transitional segment, a middle segment and a terminal plug. The middle segment and the terminal plug are formed almost exclusively by modified sustentacular cells. Each terminal segment is surrounded by a cuff-like, vascular plexus. The seminiferous tubule is succeeded by the straight tubule. The latter begins with a funnel-shaped enlargement which surrounds the terminal plug and then forms a smooth-walled, narrow tube that could be likened to the stem of the funnel. The tubular segment between the stem of the funnel and the rete is characterized by intraepithelial invaginations. The single layer of epithelium of the straight tubule and of the rete contains large numbers of free cells (lymphocytes and macrophages) which constitute up to 25 % of the epithelium. In the subepithelial stroma of the rete are free elastic fibers and flat cells which, because of their phosphatase content, are thought to be contractile.