Stem/progenitor cells in the developing human cerebellum: an immunohistochemical study

The aim of this study was to analyze, by immunohistochemistry, the occurrence of stem/progenitor cells localized in the different niches of the developing human cerebellum. To this end, cerebellar samples were obtained from 3 fetuses and 3 newborns ranging, respectively, from 11 to 24 and from 30 to 38 weeks of gestation. Specimens were 10% formalin-fixed, routinely processed and paraffin-embedded; 3 μm-tick sections were immunostained with anti-SOX2 and PAX6 antibodies. Our study evidenced SOX2 and PAX6 immunoreactivity in precursors cells in all six developing human cerebella. SOX2 was expressed in precursors of different neural cell types, including Purkinje neurons, stellate cells, basket cells and Golgi cells. In the cerebellar cortex, SOX2 expression changed during gestation, being highly expressed from the 20^th up to the 24^th week, whereas at the 30^th and at the 34^th week SOX2 immunoreactivity was restricted to the Purkinje cell layer and the inner zone. Cerebellar human cortex was negative at the 38^th week of gestation. PAX6 immunoreactivity was restricted to granule cell precursors in the external granule layer (EGL), being detected at all gestational ages. Our study indicates SOX2 and PAX6 as two useful markers of stem/progenitor cells that highlight the different germinative zones in the developing human cerebellum.