Distribution and ontogeny of parvalbumin immunoreactivity in the chicken retina

The distribution of parvalbumin-like immunoreactivity was studied in the embryonic and postnatal chicken retina. In post-hatched chickens, parvalbumin-like immunoreactivity was confined to amacrine cells. Three distinct subpopulations were identifiable based upon soma position and level of dendritic arborization in the inner plexiform layer. The primary dendrites from parvalbumin-immunoreactive amacrine cells descended vertically into the inner plexiform layer and eventually branched to give rise to a laminarly arrayed plexus in sublamina I, sublamina V and, to a lesser extent, at the boundary between sublaminae III and IV. Parvalbumin-like immunoreactive amacrine cells projecting to sublamina I of the inner plexiform layer were consistently monostratified. Some, but not all, contributed thick fibers to sublamina I that could be followed for long distances across the retina and were generally not radially organized. The parvalbumin-like immunoreactive cells that projected to sublamina V gave rise to a primary dendrite from which three to five fibers branched radially. Collateral branches of these same primary dendrites gave rise to the parvalbumin-like immunoreactive plexus at the interface between sublaminae III and IV. In prenatal chickens, parvalbumin-like immunoreactivity was not detected until embryonic day 14. At this time it appeared as a faint band at the inner nuclear layer-inner plexiform layer boundary in the central retina. By embryonic day 18 the intensity of immunoreactivity and the complexity of the arborizations of the parvalbumin-like immunoreactive dendrites approached that seen in the post-hatched chicken. In the chicken retina, parvalbumin-like immunoreactivity was displayed by morphologically distinct subpopulations of amacrine cells suggesting that these amacrine cells may subserve diverse functions.(ABSTRACT TRUNCATED AT 250 WORDS)