Histological Features of Olfactory Bulb Layers in the African Striped Ground Squirrel (<i>Xerus erythropus</i>)

Abstract

The diurnal African Striped Ground Squirrel (ASGS) (Xerus erythropus), is a member of the rodent order Rodentia and family Sciuridae. Similar to most other vertebrates, the olfactory bulbs (OB) are located most rostrally in the brain and are an integral component of the brain circuitry system responsible for the sense of smell. In this work, the layers and anatomical characteristics of OB in the ASGS were examined. Six (6) adult ASGS were sourced from villages within Zaria Local Government. They were housed in standard laboratory cages and fed with corn and carrot. Water was given ad libitum. The squirrels were euthanized via the abdomen with an injection of ketamine HCL (80mg/kg BW), followed by transcardial perfusion with10% buffered formalin. Craniotomy was carried out to expose the entire brain and the OB was carefully harvested for histological evaluation. Six layers were visible in the olfactory bulb cortex, working their way inward from the outside in. The cells observed were mitral cells, peri-glomerular, granular, and tufted cells. Interestingly, the glomerular layer was observed to be a single layer cell type which is indicative of a good olfactory acuity. It was concluded that African Striped ground squirrel’s one-layered cell thick glomerular layer is indicative of good olfaction and sense of smell giving the ASGS an advantage for navigation in search for food and protection from predation.