Study of adult neurogenesis in the gallotia galloti lizard during different seasons

In a previous study we found a seasonal distribution of cell proliferation (the first stage of adult neurogenesis) in the telencephalic ventricular walls of the adult Gallotia galloti lizard. The aim of the present work was to determine the influence of seasonality on the subsequent migration of the resulting immature neurons. We used wild animals injected with bromodeoxyuridine and kept in captivity within 30 days. To confirm the neuronal identity of these cells, we used double immunohistochemical 5-bromo-2′-deoxyuridine (BrdU) and doublecortin (DCX, an early neuronal marker) labeling, as well as autoradiography after the administration of methyl-[3H]thymidine ([3H]T). We found that: (1) the rate of cell division and/or migration from the ventricular walls varied with the season, especially in regions related with olfaction. (2) Immature neuron-like cells appeared to migrate in an apparently radial and tangential way towards different parts of the telencephalic parenchyma. (3) We did not observe ultrastructurally mature neurons until at least 90 days later, a period considerably greater than that reported for other species of vertebrates in similar studies.

Research highlights
► We studied adult neurogenesis in G. galloti lizards during different seasons.
► We used wild animals injected with mitotic markers and kept during 30 days.
► Newborn cells gave rise to immature neurons in the majority of cases.
► Regions related with olfaction showed remarkable seasonal fluctuations.
► Mature neurons were not ultrastructurally observed until at least 90 days later.