THE MORPHOLOGY OF THE OLFACTORY ORGAN OF THE PACIFIC SALMON (ONCORHYNCHUS)

Abstract

The surface area of the olfactory epithelium of Pacific salmon (Oncorhynchus spp.) is about 40% of the retinal area in 10- to 60-cm fish. In salmon up to 12 cm, growth of the olfactory epithelium occurs by increase in the size and number of the olfactory lamellae, in larger fish only by increase in the size of the lamellae. In adult salmon these primary lamellae develop secondary lamellae which can be seen in the unfixed tissue. The secondary lamellae, up to 10 in each primary lamella, consist only of a non-sensory mucous epithelium. Similar secondary lamellae were found in large rainbow trout (Salmo gairdneri) and seem to be characteristic of salmonids.