Figure 2: Morphological characterization of S. aurata primary neuroglial cultures. Phase-contrast microscopy pictures showing development and differentiation steps of Neuroglial Restricted Precursor cells (NGRPs). (a) NGRP cluster of stem cells at the early stage of neurosphere. (a’) Highly branched neurosphere in adhesion morphology. (a’’) Early stage of radial fiber generation: basal fiber cell of radial glia forming a short stub protrusive from the soma. (b, c, d) Early radial glia cluster producing basal glial cells; the NGRPs extend their basal process in a radial direction, thus gaining the typical form of radial glial rosette-like colony. (e) Phase-contrast image showing a rosette like colony of radial glia with early elongated protrusions after 2 weeks of culturing (×200). (e’) An enlargement of cells in (e) showing a particular of the radial colony with areas of active neuronal proliferation and first dividing cells generating neurons (×400). (f) Phasecontrast image showing a rosette colony of radial glia with a blue filter enlightening newly formed neurons after 2 weeks of culturing. (g) Scheme represents development and differentiation of neuro-glial restricted precursor cells (NGRPs) astrocytes, oligodendrocytes, and radial glial cells. Scale bar = 10 μm (a-d); 50 μm (e-f).