Fine structure of the olfactory epithelium in the goldfish, Carassius auratus. A study of retrograde degeneration.

The fine structure of the goldfish olfactory epithelium was studied by transmission and scanning electron microscopy. Six different cell types were distinguished. Identification of the olfactory receptor cell was accomplished by use of retrograde degeneration studies. Two morphologically distinct types of olfactory receptor cells were identified: one type bears radially oriented cilia (Type I cell); the other type bears microvilli (Type II cell). The other four cell types were not identifiable as olfactory receptor cells: they are ciliated cells (Type III), rod-shaped cells (Type IV), supporting cells (Type V), and basal cells (Type VI).