PRENATAL DEVELOPMENT OF CALBINDIN D-28K AND PARVALBUMIN IMMUNOREACTIVITIES IN THE HUMAN RETINA

Two calcium binding proteins, calbindin D-28K (CB) and parvalbumin (PV ),immunoreactivities were examined by immunocytochemistry in the retin as of human fetuses aged from 13 weeks (W) of gestation to term. CB- a nd PV-immunoreactive products were both detectable at 13 W and appeare d in all layers in a roughly inside-out order by 24 W. PV-immunostaini ng occurred in virtually all ganglion cells, most horizontal cells, an d a few amacrine cells. CB-immunoreactivity was found in most amacrine cells and some horizontal cells, and a subset of cells in the ganglio n cell layer that were more frequent in the nasal than the temporal re tina at 13-15 W. Bipolar cells were distinctly immunostained for CB by 24 W. Foveal cones showed faint CB labeling by 24 W and intense stain ing at 32 W. The patterns of CB- and PV-immunoreactivities by birth we re similar to those at 32 W with the addition of faint CB-immunolabeli ng occurring beyond the fovea in the photoreceptors. A stronger expres sion of CB was seen in the nasal side of the optic ner-ie head from 13 -24 W, peaking at 15 W. The results indicate that CB and PV expression in ganglion cells and inner nuclear layer neurons proceeds in paralle l with their somal and process differentiation, suggesting a possible role for these proteins in neuronal maturation. The early expression o f PV and CB in ganglion cell axons might be related to optic nerve out growth, including path-finding at the optic chiasm. CB expression in c ones and other cells in the fovea may indicate that it is involved in foveal formation that occurs during the perinatal period. (C) 1997 Wil ey-Liss, Inc.