Relationships between summer thermal variations and cell proliferation in heterothermic vertebrates, as revealed by PCNA expression in the brain of adult Rana bergeri (Günther, 1986)

About the issue if the natural encephalic proliferative activities can be influenced by the seasonal (thermal and photoperiodic) cyclic fluctuations in adult earth-dwelling Anamnia and poikilothermal Amniota there is a gap regarding expressly summer season alone in literature reports on autoradiographic studies in frog. The actual study suggests that the brain proliferative pattern in Rana bergeri collected in the wild in summer is intermediate between those previously observed in spring and autumn. This would seem to indicate a proliferative increase from spring to autumn. This pattern mainly appears in the forebrain, typically in the olfactory portion where the stem cells are identifiable as scattered “matrix“ cells in the ependyma and grey matter, and in the telencephalic district, where these cells are grouped as “matrix” areas in the well-known zonae germinativae dorsales and ventrales.