Anamnia Research Articles

Relationships between seasonal (spring, summer, autumnal) thermal variations and cell proliferation in heterothermic vertebrates, as revealed by PCNA expression in the brain of adult Triturus carnifex

Inspired both by the literature reports and our previous findings on the question if a seasonal cycle alone, consisting of temperature and photoperiod variations, might impact on or activate natural proliferative fluctuations or unmask a latent spontaneous proliferative power in adult brain of poikilothermal Anamnia (fresh water, earth-dwelling) and Amniota (terrestrial), consequently allowing for encephalic reparative and even regenerative potentialities, an investigation has been carried on in normal adult brain of Triturus carnifex caught in nature in spring, summer, autumn. Cells immunostained for PCNA, i.e. cycling cells, were found scattered (“matrix cells”) in the olfactory territories, where they appeared scarce in spring, more frequent in summer, noticeable in autumn; also, immunostained cells were found clustered in “matrix areas”, also named zonae germinativae dorsales and ventrales, in the telencephalic hemispheres: few clusters in spring, an intermediate condition in summer, frequent cell groups in autumn. These results reveal an increasing trend in proliferation from spring, through summer, to autumn. This scenario was appreciable in the forebrain, mainly in the olfactory and telencephalic districts, which is the typical site of stem cells. Signs of potential proliferative activity are well appreciable in the urodele Amphibians, which are the best provided among vertebrates with reparative and regenerative power and possess the richest endowment of dormant cells susceptible to be recruited to proliferation.

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.