Calbindin D-28k-immunoreactive neurons in chick dorsal root ganglion: ontogenesis and cytological characteristics of the immunoreactive sensory neurons.

The expression of calbindin (28,000 mol. wt Vitamin D-dependent calcium binding protein) was studied in sensory neurons of the chick dorsal root ganglion by combining immunocytochemical and ultrastructural features. In the chick embryo at E10, about 20% of the neuroblasts were immunostained with antibodies raised to calbindin. After hatching, two subpopulations of primary sensory neurons were labeled with calbindin-antibodies and could be identified: the large Al cell bodies (6%) mainly characterized by huge blocks of rough endoplasmic reticulum and the small B1 cell bodies (14%) which contain parallel cisternae of rough endoplasmic reticulum. The other neuronal cell types A2 and B2 were devoid of any immunostaining. Thus, calbindin is an early and reliable marker of two subclasses of primary sensory neurons in the chick dorsal root ganglion.