Anatomy and morphometry of the olfactory organ of the wels Silurus glanis L. (Siluridae, Pisces)

The anatomical structure of the olfactory organs, nerve tracts and brain was described in Silurus glanis. The changes connected with aging were considered. The olfactory lamellae are thin and tightly set in a rosette. In the 1 year old individuals there are 48...51 lamellae in a single rosette. This number increases gradually with age and in the 9...10 year old welses reaches 150. The surface area of the lamellae of a single rosette also indicates an increase: in the 1 year old specimen it equals 117 mm2, while in the adult individual (5...6 year old)--1040 mm2. This is due to the increase in both the size of each lamella and the number of the lamellae. The obtained results are discussed with regard to other author's data. It has been found that the dynamics of the increase of the surface area of the olfactory epithelium in fish are closely related to the way of life and not to the systematic affiliation of the species.