CONICET | Buscador de Institutos y Recursos Humanos

Pituitary folliculo-stellate (FS) cells have been investigated in several vertebrates to elucidate their function and origin. In our Laboratory we study the reproduction and adaptation mechanisms of viscacha (Lagostomus maximus maximus). It?s a native rodent with nocturnal habits and seasonal reproduction. The purpose of the present work was to study the pituitary FS cells in the Lagostomus. The pituitaries of adult male viscachas were analyzed by immunohistochemistry techniques and transmission electronic microscopy. Lanthanum hydroxide was used as electrodense tracer. In the immunohistochemical study S-100 and glio-fibrillary acidic (GFAP) proteins were localized. The FS cells show cytoplasmic and nuclear immunolabeling for S-100 and cytoplasmic immunolabeling for GFAP. They are forming follicles with colloidal lumen, present cytoplasmic processes between endocrine cells. The ultrastructural study shows FS cells with irregular nucleus, moderate numbers of mitochondria, scarce rough endoplasmic reticulum and absence of secretory granules. The lateral membranes of the apical region are joined by prominent junctional complex and desmosomas. From the apical poles of the cells, microvilli protruded into the follicular lumen. The tracer penetrates freely into the intercellular spaces, delineating the cellular border of granulated and FS cells. Our results suggest that the FS cells of viscacha originate an extensive and permeate canalicular network of intercommunicated spaces freely between the granulated and FS cells. This cellular interaction probably is involved in the hormonal release control. Besides, the expression of S-100 and GFAP proteins might indicate a neuroectodermal origin of the FS cells in the Lagostomus.

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