FINE STRUCTURE OF OLFACTORY TRACT IN TELEOST CARASSIUS CARASSIUS L

Electronmicrographic montages of the olfactory tract at two levels in each of two fish (Carassius carassius L.) were constructed and fibre diameters measured using a Zeiss TGZ 3 particle size analyzer. Medial and lateral tract divisions, rhinocele and dorsal tela were identified. Ciliated ependymal cells line the rhinocele. Meninges form the outer covering of both tract divisions and the tela roofing the central canal. The lateral tract consists of 10-14 fasciculi in which myelinated nerve fibres are prominent. These fibres range in diameter between 0.2 μ and 1.8 μ (mean 0.7 μ) consistent with conduction velocities averaging 0.6 m/sec recorded in the carp lateral olfactory tract. The medial division of the olfactory tract contains two larger fasciculi within which are numerous fine unmyelinated nerve fibres (mean diameter 0.17 μ) arranged in bundles partly enveloped by glial cell processes. Myelinated nerve fibres are unevenly distributed within both fasciculi and have mean diameters of 0.6 μ. An interesting observation is the consistent presence of synapses within the largest bundle of the medial tract at all levels. © 1968 Springer-Verlag.