Cell proliferation in the olfactory bulb of adult freshwater teleosts.

The olfactory bulb of adult specimens of Carassius auratus was subjected to an autoradiographic study using [3H]thymidine. Adult specimens of Carassius auratus, Barbus meridionalis, Cyprinus carpio and Salmo gairdneri were also studied using light and electron microscopy. Cells were found undergoing mitotic division with two characteristic locations: a group can be seen near to the ventricle or ventricular recess; these cells can be identified as granule cells or precursors of granule cells. Other cells undergoing division are seen on the outer limiting glial membrane and in the olfactory nerve fibre layer; these cells are identified as astrocytes. Different hypotheses about the destination and meaning of these proliferating cells and the similarities and differences with the cell proliferation in adult higher vertebrates are discussed.