Investigation of fibre structure of olfactory tract in human

2SUMMARYNervus olfactorius (1st cranial nerve) is a collection of sensory nerve fibres.Olfactory cells of N olfactorius (bipolar ganglion cells) is present in the nostrils(regio olfactoria) from where they extend to the bulbus olfactorius. The aim of thisstudy was to investigate the fibre structure of the tractus olfactorius, which is animportant neuronal junction.Forty bulbus and tractus olfactorius tissue samples were obtained from 20cadavers for analysis. Tissue samples were stained with H&E (Hematoxylin-Eosin)and histologically examined. Macroscopic examination revealed that the lengths ofleft and right bulbus olfactorius were 0.74±0.02 cm; while the length of left and righttractus olfactorius, located in the sulcus olfactorius, was 4.82±0.13cm. Whenexamined microscopically, a layered structure of the olfactory bulb was immediatelyapparent. These layers (n=6) were; the layer containing olfactory nerves withoutmyelinated axons, the glomerulus layer, molecular and outer granular layer, mitralcell layer, inner granular layer and the layer of tractus olfactorius.In the light of our findings and information available in literature, it wasfound that the fibrous structure of tractus olfactorius contains, in addition to mitraland tufted cells in the bulbus olfactorius, efferent axons leaving higher brain regionsfrom the anterior nucleus olfactorius and the opposite bulbus olfactorius.Key words: The olfactory tract structure, olfactory bulb, olfaction.