Histology and Brain Derived Neurotrophic Factor immunoreaction of the neurons in the corpora quadrigemina of the African grasscutter (Thryonomys swinderianus – Temminck, 1827)

Abstract

The African grasscutter is the second largest rodent in Africa, thus, a key component of the minilivestock industry. The study described the histological features and probed the distribution of Brain Derived Neurotrophic Factor (BDNF) in the corpora quadrigemina of the African grasscutter at foetal and postnatal developmental periods. Brain samples from foetuses explanted on foetal days 60 (F60) and 90 (F90) and extracted from 3 and 6-days-old pups (P3 and P6, respectively), 72-days-old juveniles (P72) and 450-days-old adults (P450) were used. They were prepared for histology and immunohistochemistry. Three laminae were distinct in the rostral colliculi at the foetal and postnatal periods; an outermost stratum zonale, middle stratum griseum superficiale and an inner stratum griseum profundum. Stratum griseum intermediale and stratum medullarium were not distinct. On F60 and F90, the stratum zonale was made of immature neurons, devoid of neurites; the central nucleus of the caudal colliculus was also made of immature migrating neurons. On P3, the neurons were already mature. The stratum zonale was made of medium-sized neuronal cells and thick processes. The thickness of this layer decreased with age. On P3, the caudal colliculus was made of all the components typical of a developed caudal colliculus. There was no BDNF immunoreactive cell in the stratum zonale at any postnatal period; a moderate BDNF-immunoreactivity in the stratum griseum superficiale on P3, a mild immunoreactivity on P6, none reactivity on P72 and mild on P450. The dorsal and lateral cortices of the caudal colliculus were none reactive to BDNF at any postnatal period. The results suggest a better auditory than visual capacity in the rodent.

Comparative cytoarchitecture of the midbrain colliculi of defined age groups in the African giant pouched rat (Cricetomys gambianus)

“…The three layers of the rostral colliculus in the neonate, juvenile and adult African giant pouched rat shown in the present study corresponded to the study conducted in the African grasscutter rostral colliculus by Ibe et al (2019). However, the migratory immature neurons of the radial glial found in the SZ of the neonate rostral colliculus in the present study was already mature in the neonates of the African grasscutter (Ibe et al, 2019). This implies that the neonate African grasscutter may have better vision than their African giant pouched rat components.…”

“…This implied that the adult caudal colliculus was most developed, followed by that of the juveniles; the neonatal caudal colliculus was still immature. These agreed with the work of Ibe et al (2019) on the African grasscutter partly, especially for the neonates and juveniles but differed in the adults. However, statistical comparison of the lengths of the central nucleus of the caudal colliculus indicated that the juvenile and adult were each better developed than the neonate.…”

“…The developed components of the acoustic pathway, from this study, probably highlights the auditory demands of percussive foraging in the African giant pouched rat. These three divisions of the caudal colliculus in the three age groups corresponded to the findings in the African grasscutter by Ibe et al (2019). However, the presence of the migratory immature neurons and numerous blood vessels in the neonates is suggestive of possible neuronal ablation, high energy demand for cell metabolism and rapid vascularization of this group.…”

Anatomical studies on the African grasscutter (Thryonomys swinderianus), a key component of the minilivestock industry in Nigeria

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“…Bhagwandin et al (2006), Byanet, Nzalak, Salami, Umosen, et al (2008), Nzalak et al (2008), Byanet et al (2009), Ajayi et al (2011), Byanet et al (2012), Obadiah and Obadiah (2014), Byanet et al (2018). Dwarika et al (2008), Mustapha et al (2015), Ibe et al (2016), Ibe et al (2017), Mustapha et al (2017), Ibe, Salami, et al (2018), Ibe, Ikpegbu, and Nlebedu (2018), Ibe, Salami, et al (2019), Ibe, Ojo, et al (2019); Ibe et al (2020)…”