Morphological evidence of cyclic changes observed in Leydig cells of a chimeric mouse

Light and electron microscopy were employed in studying morphologic heterogeneity in Leydig cells (LC) in situ, as manifested in a chimeric mouse. This mouse was chosen to take advantage of increased LC concentration in territories of agametic tubules (Hrudka et al., 1989). Large number of LC's, side by side, gave better opportunity to compare their size, shape, organelle representation, surface specialization and mutual interaction. Because cell organelles and inclusions were distinctive, we were able to monitor their dynamics and changes in cell shape and size, as well as phenomena in the intercellular space. In spite of an apparent continuum, a series of definite forms or stages were identified, in the course of the study. After arranging these reproducible and predictable forms in a logical sequence, the following, tentative cycle of secretory activity of LC is proposed: 1) stage of transient or 'lean' cell, 2) stage of SER proliferation and cell hypertrophy, 3) stage of lipid deposition or 'fat' cell and 4) stage of regression.