Comparative Postnatal Cytoarchitectural study of the Cochlear and Vestibular nuclei in the African giant rat (Cricetomys gambianus)

The medulla oblongata relays impulses between the spinal cord and higher brain centers and serves as the control center for autonomic processes. The gray matter of the medulla oblongata houses the cochlear and vestibular cranial nerve nuclei, and they are involved in the control of essential bodily activities. Information on status of the auditory reflex centres at earlier postnatal developmental stages of the African giant rat (AGR) is lacking in available literature. Previous studies advocated the use of juveniles instead of adults for neurological studies. The cytoarchitecture of the cochlear and vestibular nuclei at different postnatal developmental stages in AGR need to be investigated to further understand the variation in the auditory capacity of this rodent. It is with this dearth of knowledge on the auditory brain centres of the AGR that the need to conduct the present study was born. Neuronal axons of cochlear bushy cells were absent in neonates, present but short in juveniles and well developed in adults. The relatively poor acoustic structures in neonates, improved acoustic structures in juveniles and dominant acoustic structures in adult AGRs is Progressive. This progressive development of cochlear bushy cells from neonates, through juveniles to adults implies that the adults have huge auditory nerve endings for high fidelity neural transmission in response to acoustic events more than the juveniles and far less in neonates. Therefore, the adults of AGR have the best auditory sense acuity, followed by a good one in juveniles and the worst in neonates.