Descriptive kinetics of the seminiferous epithelium cycle and genome size in the mole Talpa occidentalis (Insectivora)

The male germ cell cytodifferentiative process of the mole Talpa occidentalis is described. Cytochemical procedures were used 1) to follow acrosome formation and spermatid differentiation, dividing the seminiferous epithelium cycle into ten stages, each characterized by typical germ cell-to-cell associations, and recognizing 13 steps in spermatid differentiation; 2) to monitor, in situ, histones replacement by protamines at step 11 of the spermiogenic process. The seminiferous epithelium cycle of the mole has the basic histological features present in all mammals and appears rather similar to that of the common shrew (Sorex araneus), the only one so far known among Insectivora. The metabolism of the DNA-associated proteins reveals that protamines replace histones during the late steps (11–13) of spermiogenesis, mRNA for protamines having been synthesized at an earlier step (assuming that in the mole this occurs at the first spermiogenic steps, as in the house mouse). In addition the genome size (5.0 pg) and the AT/GC ratio (1.3) were evaluated. © 1995 Wiley-Liss, Inc.