Immunohistochemical localization of taurine in the retina of developing and adult human and adult monkey.

The localization of taurine in the retina of fetal (12-25 weeks of gestation), postnatal (five-month-old infant) and adult human (35- and 65-year-old) was examined by immunohistochemistry. Additionally, retinas of fresh adult monkey, which served as positive controls, were employed. No immunoreactivity was found in the fetal retinas from 12-15 weeks of gestation. At 1617 weeks of gestation, the ganglion cells and some of their axons were conspicuously labelled for taurine. At 18-19 weeks, Muller glial endfeet, the inner plexiform layer, some amacrine and putative horizontal cells and photoreceptors showed moderate immunoreactivity. With further development at 20-21 and 24-25 weeks of gestation, the immunoreactivity was prominent in Muller cell endfeet, some bipolar cells and in horizontal cells that were aligned in a row in the inner nuclear layer, close to the fovea. At both fetal stages, the photoreceptors and horizontal cells showed strong immunoreactivity. In the postnatal infant retina, taurine immunoreactivity was present in some amacrine cells and photoreceptor inner segments and nuclei, but not in ganglion and horizontal cells, which was also the pattern noted in the adult monkey and human retinas. With development, a shift in the intensity of taurine immunoreactivity was noted towards the outer retina. The expression of taurine immunoreactivity in most fetal retinal neurons implies a role for this amino acid in the normal development as well as maturation of human retina.