HUMAN RETINAL GANGLION-CELL DEVELOPMENT IN EARLY PRENATAL PERIOD USING CARBOCYANINE DYE DII

Early development of retinal ganglion cell morphology has been studied in human fetuses of gestational age ranging from 7-8 weeks to 19-20 w eeks by retrograde labelling with a lipophilic fluorescent dye, DiI. T he retinal ganglion cells with simple and relatively uniform appearanc e having few dendritic processes between 7 to 11 weeks of gestation sh ow progressive growth and elaboration of dendrites at 17-18 weeks reve aling some morphological variation in shapes. It is by 19-20 weeks of gestation that the three major ganglion cell types resembling the alph a, beta and gamma classes of cat ganglion cells are identifiable in th e developing human retina. The dendrites of some ganglion cells exhibi t varicosities, filiform processes and spines even as early as 10-11 w eeks indicating a possibility of involvement in synaptic connectivity.