Cinética das espermatogônias em camundongos Knockout Tex14 com ausência de pontes intercelulares

Abstract

Intercellular bridges are cytoplasmic channels that interconnect clones of germ cells in a syncytium. It has been predicted that the intercellular bridges have a fundamental role in the communication and synchronization of the germ cells, mediating the transit of apop-totic and mitotic signals between spermatogonial clones and for coordinating the entry into meiosis. Tex14 knockout mice are genetically unable to produce the protein TEX14. This protein is essential for the maintenance of the intercellular bridges and its absence results in sterility. Previous studies on Tex14 knockout mice did not investigate details of the proposed roles attributed to the intercellular bridges by morphological approaches. Hence, the present study evaluated the intercellular bridges participation in the seminiferous epithelial synchronism using high-resolution light microscopy (HRLM), immunohistochemistry (bromodeoxyuridine BrdU for detection of pro-liferating cells in living tissues) and transmission electron microscopy (TEM). The spermatogonial morphology was not affected by the lack of intercellular bridges, but spermatogonial kinetics was impaired in the proliferation of the Aundifferentiated spermato-gonia, which generate the pool committed to differentiate to A1, and B spermatogonia, that generate the pool of spermatocytes committed to meiosis. Some B spermatogonia and the preleptotene spermatocytes were seen far from the basal lamina and others in the intermediated compartment. In the transition of proliferative and meiotic phases, there was a first moment of apoptosis that reduced the number of preleptotene primary spermatocytes. Afterwards, pachytene primary spermatocytes were completely depleted from spermatogonial stage 5 onwards. The results confirm the importance of intercellu-lar bridges in the synchronization of the germ cells and coordination of the critical events like differentiation into A1 and meiosis.