[The structual and temporal characteristics of four intermediate filament proteins during retinal development of rat]

To investigate the markers of retinal progenitor cells and their spatio-temporal characteristics during retinal development of rat.

The time sequence, location and intensity of the expression of four intermediate filament proteins in retina were studied in rats (from postnatal day 0 to 12 months) by means of immunohistochemistry staining.

Retinal differentiation of rat was not accomplished until 2 weeks after birth. Nestin positive cells were seen in neurocytes, glial cells and capillary endothelial cells of rat retina 2 weeks after birth. The number of Nestin positive cells and intensity of Nestin staining in rat retina decreased obviously after 2 weeks of birth then turned to negative at 4 weeks after birth. However, the expression of Nestin was persisted in cells from a few ciliary processes during the development and the intensively positive staining cells were observed in ciliary process, mostly in pigment epithelium cells in adult. In addition, Nestin positive cells were also found in the optic nerve of adult rat. The expression pattern of Vimentin is similar to that of Nestin within 2 weeks after birth. But the expression of Vimentin was persisted with high level lifetime in all glial cells and nonpigment epithelium cells of ciliary. Besides the horizontal cells, positive staining of Vimentin was also found in Muller cells and amacrine cells at 4 weeks after birth. The positive expression of GFAP and neurofilament were only found in mature glial cells and in the axons of ganglion cells, respectively.

Nestin could be considered as the marker of retinal progenitor cells. Retinal progenitor cells of adult rat are also present in optic nerve and in a few ciliary processes.