PCNA-negativity in the telencephalon of adult female songbirds (Serinus serinus): absence of signs of normal proliferation.

In a recent study, we demonstrated the persistence of normal proliferation in the telencephalon of adult male songbirds (Serinus serinus), as shown by the expression of Proliferating Cell Nuclear Antigen (PCNA), a test that uses monoclonal antibodies to reveal cells in the S phase. Near the start of the breeding season, this proliferation was observed in circumscribed areas of the ventricular ependymal epithelium (zona germinativa dorsalis and zona germinativa ventralis) and in small masses of cells that were grouped or separated ("hot spots"). Therefore, we decided to extend this research to normal adult females of the species, using the same marker and the same time period as in the previous study. This time, however, we did not observe PCNA-positivity, and thus any sign of natural proliferation, in the telencephalic areas that showed it in the male songbirds. The immunocytochemical patterns recorded in females and males of Serinus serinus agree with the information reported in the literature, namely that in adult homeothermic Vertebrates the presence of spontaneous cerebral neurogenesis is limited to male songbirds.