Postnatal neurogenesis in the olfactory bulbs of a lizard. A tritiated thymidine autoradiographic study

Autoradiographically labelled cells were observed in the olfactory bulbs of perinatal, young and adult specimens of the lizard Podarcis hispanica following intraperitoneal injection of tritiated thymidine (5 muCi/g b.wt). After survival times of 7, 18 and 28 days labelled cells were found in the granular layer of both main and accessory bulbs. A few labelled cells were observed in the ependyma, mitral and glomerular layer. In the main olfactory bulb, one week of survival time resulted in labelling of cells in the innermost part of the granular layer. Longer survival times (up to 4 weeks), resulted in labelling of cells mainly in the outermost part of the granular layer. This spatio-temporal gradient was not observed in the accessory bulb. Nevertheless, longer survival times resulted in greater number of labelled cells located in the dorsal and ventral parts of the granular layer of the accessory bulb.