3. Electronic Theses and Dissertations (ETDs) - All submissions

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Neurogenesis in the central nervous system of the Nile crocodile (Crocodylus niloticus) throughout ontogenesis
(2015) Ngwenya, Ayanda
The body and central nervous system of the Nile crocodile (Crocodylus niloticus) is known to grow continuously, even past sexual maturity. Previous studies on crocodilians show a gradual decrease in the rate of growth of the brain as individuals mature; however, the data on brain growth are limited and there are no data on growth rates of the spinal cord and retina. The current thesis provides a description of the growth rates of the brain, spinal cord and eye (ocular volume) of 70 juvenile and sub-adult Nile crocodiles ranging between 92 g and 90 kg in mass. Body growth in the crocodiles is accompanied by growth of all central nervous system structures (brain, spinal cord and eye), although growth occurs at different rates, with the spinal cord being the fastest growing structure, followed by the eye and the brain. The neurogenic regions (areas to which new neurons are continuously added) of the brain were revealed using doublecortin immunohistochemistry. Labelled cells were observed in all the regions of the telencephalon (including the cortical mantle, dorsal ventricular ridge, striatum, septal nuclei and the olfactory bulbs) as well as the molecular and granular layers of the cerebellar cortex, but not in the diencephalon or brainstem.