THE INTERMEDIATE FILAMENT PROTEIN NESTIN OCCURS TRANSIENTLY IN DIFFERENTIATING TESTIS OF RAT AND MOUSE

Nestin is an intermediate filament (IF) protein (IFP) which occurs dur ing early developmental stages and during regenerative processes in mu scle and neuronal cells, The spatial and temporal localization of nest in in the developing testis of rat and mouse was studied by immunolabe ling light and electron microscopy and by immunoblotting. Nestin local ization was related to the localization of the other major IFPs specif ic for this tissue, i.e. cytokeratins, vimentin and desmin. Laminin im munocytochemistry and conventional microscopy were used to identify ti ssues and cells. With the incipient differentiation of the gonadal anl age, the reaction for nestin was weak in the gonadal ridge, whereas th e cells of the mesonephric mesenchyme showed a prominent reaction for this IFP. The nestin-specific reaction in the epithelial mesonephric d uct and tubules was weak and disappeared at an early phase of differen tiation. With the development of the testis proper, nestin was transie ntly found in several cell types, Nestin was found as well as vimentin and cytokeratins in the Sertoli cells. In the interstitial cells nest in was found together with vimentin and desmin IFPs, and was most prom inent in the differentiating myoid cells. After birth, nestin graduall y disappeared from the testicular cells and in the rat at puberty was found only in the endothelial cells of some blood vessels. The abolish ed nestin synthesis in the testis was confirmed by immunoblotting. The se results suggest that nestin is required transiently during the deve lopment of the testis and mesonephros. The temporary presence of nesti n, and several other IFPs during these phases, coincides with key phas es of urogenital sex differentiation. This may imply that the orchestr ated synthesis of the IFPs nestin, cytokeratins, vimentin and desmin i s likely to be linked with the genes regulating sex differentiation.