Glial Cells Ontogeny in the Telencephalon and Mesencephalon of the Lizard Gallotia galloti

In contrast to the extensive literature on mammalian gliogenesis, relatively little attention has been paid to lower vertebrates and particularly to reptiles. Along this chapter we have documented the distribution of macroglial cells and the modifications of their precursors during ontogeny in the central nervous system (CNS) of the lizard Gallotia galloti by using histological, immunohistological methods, and electron microscopy. Our observations showed that most glial cell phenotypes in Gallotia galloti and the sequence of their morphological differentiation and maturation do not greatly differ from those of mammals. However there are some differences that should be pointed. The first striking feature is the different glial distribution between telencephalon and mesencephalon as demonstrated by double-labelling immunocytochemistry. Another remarkable feature is the large proportion of radial glial cells present in the adult brain. Finally, another particularity of special interest, is the presence of immature cells in some ventricular sulci throughout lizard lifetime. Probably, the abundance of immature cells in mesencephalic and telencephalic sulci of adult nuclei could be related to the regenerative capacity of reptilian CNS.