The Macroglia Of Teleosts: Characterization, Distribution and Development

We present morphological, immunocytochemical and developmental studies on the macroglia of species of two groups of teleosts carried out in our laboratories. One of these species, the grey mullet (Chelon labrosus; Acanthopterygii), is an advanced euteleost. The other species are trouts (Salmo trutta fario, Oncorhynchus mykiss; Protacanthopterygii) which belong to the basal stock of euteleosts. We present our results on a specialized astroglial structure of the medulla oblongata of the adult grey mullet, the distribution of astroglial markers (vimentin, GFAP and S-100) in the brain of the adult mullet and their pattern of expression in juveniles of 5 to 70 mm in length, as well as results obtained with S-100 and GFAP immunocytochemistry in trout. In old adult mullet (circa 50 cm in length), we have studied with light and electron microscopy the diversity of oligodendrocytes of the lateral line area of the medulla oblongata. In the brain of old adult trout (circa of 36 cm in length), the NADPHd histochemical reaction was used to study the large population of oligodendrocytes. Finally, we studied the development of the oligodendrocytes in trout using an antibody to the 36K myelin protein. Our results in old adults of two species pertaining to different lines within teleosts showed that diversity of oligodendrocyte sizes in different regions of the brain is a shared characteristic of teleosts and mammals.