Localized morphological differentiation in the bipolar cells of the chick retina

On a morphological and ultrastructural level, we studied a thickening which appears on the ascending prolongation of bipolar cells in the chick retina. We first observed this thickening on day 10 of incubation and it remains unchanged throughout the postnatal life of the chick. Its presence seems to be related to the synaptic activity at a dendritic level in certain bipolar cells.