Phyletic distribution of crypt-type olfactory receptor neurons in fishes

The olfactory epithelium of teleost fishes contains ciliated and microvillo us olfactory receptor neurons intermingled with supporting cells. Recently the crypt cell, a third type of olfactory receptor neuron (ORN), was descri bed for two ostariophysans. This type of ORN bears apical microvilli as wel l as occult cilia extending into a crypt at the apex of the cell. The prese nt study used scanning and transmission electron-microscopic methods to exa mine how widespread this cell type is in other groups of fish. We investiga ted the olfactory epithelia of 18 species, freshwater and marine, including various actinopterygian fish as well as 2 species of lungfishes belonging to the sarcopterygians. Crypt cells were detected in 13 species of actinopt erygian fish, but in none of the sarcopterygian lungfishes. Crypt cells are present in basic as well as in highly derived actinopterygians. We conclud e that crypt cells are a common feature of actinopterygian fish. Copyright (C) 2000 S. Karger AG, Basel.