Structural organization of the olfactory bulb of wild ferret pigeon (<i>Columba livia</i>)

Abstract

Fourteen brain samples (Ten for morphometry, two for gross and two for histological studies) were used in this study. The mean body weight of the wild ferret pigeon was 214 ± 13.37 g. The brain weight, length and width obtained from this study was 1.61 ± 0.07 g, 11.41 ± 0.25 cm and 15.62 ± 0.25cm. The mean height and volume were 12.04 ± 0.30 cm and 1.66 ± 0.9 cm³. There were significant differences between mean brain weight and volume. Morphologically, the olfactory lobe was observed to be bilobed structures on the rostro-ventral aspect of the cerebral hemispheres and was smaller compared to the entire cerebrum. The cellular layer was observed to be made up of; the olfactory nerve layer, glomerular layer, mitral cell layer and granule cell layer. The mitral or tuft cells resembles small pyramidal cells whose nuclei were centrally located, dark stained and are principal neurones of the olfactory lobe. Some of the processes were directed towards the granule and glomerular layers. The granular cells were numerous with dark stained nuclei. There is a corresponding increase in the brain volume as the brain weight increases. Grossly, the olfactory bulb is not developed. The mitral cell confers olfaction in animals as such, this bird has better olfaction compare to other birds.

Keywords: Structural, organization, olfactory, wild, pigeon