Adult neurogenesis in the four-striped mice (Rhabdomys pumilio)

In this study, we investigated non-captive four-striped mice (Rhabdomys pumilio) for evidence that adult neurogenesis occurs in the adult brain of animal models in natural environment. Ki-67 (a marker for cell proliferation) and doublecortin (a marker for immature neurons) immunostaining confirmed that adult neurogenesis occurs in the active sites of subventricular zone of the lateral ventricle with the migratory stream to the olfactory bulb, and the subgranular zone of the dentate gyrus of the hippocampus. No Ki-67 proliferating cells were observed in the striatum substantia nigra, amygdala, cerebral cortex or dorsal vagal complex. Doublecortin-immunoreactive cells were observed in the striatum, third ventricle, cerebral cortex, amygdala, olfactory bulb and along the rostral migratory stream but absent in the substantia nigra and dorsal vagal complex. The potential neurogenic sites in the four-striped mouse species could invariably lead to increased neural plasticity

The dynamics of adult neurogenesis in human hippocampus

The phenomenon of adult neurogenesis is now an accepted occurrence in mammals and also in humans. At least two discrete places house stem cells for generation of neurons in adult brain. These are olfactory system and the hippocampus. In animals, newly generated neurons have been directly or indirectly demonstrated to generate a significant amount of new neurons to have a functional role. However, the data in humans on the extent of this process is still scanty and such as difficult to comprehend its functional role in humans. This paper explores the available data on as extent of adult hippocampal neurogenesis in humans and makes comparison to animal data

Histology and ultrastructure of transitional changes in skin morphology in the juvenile and adult four-striped mouse (Rhabdomys pumilio)

The four-striped mouse has a grey to brown coloured coat with four characteristic dark stripes interspersed with three lighter stripes running along its back. The histological differences in the skin of the juvenile and adult mouse were investigated by Haematoxylin and Eosin and Masson Trichrome staining, while melanocytes in the skin were studied through melanin-specific Ferro-ferricyanide staining. The ultrastructure of the juvenile skin, hair follicles, and melanocytes was also explored. In both the juvenile and adult four-striped mouse, pigment-containing cells were observed in the dermis and were homogeneously dispersed throughout this layer. Apart from these cells, the histology of the skin of the adult four-striped mouse was similar to normal mammalian skin. In the juvenile four-striped mouse, abundant hair follicles of varying sizes were observed in the dermis and hypodermis, while hair follicles of similar size were only present in the dermis of adult four-striped mouse. Ultrastructural analysis of juvenile hair follicles revealed that the arrangement and differentiation of cellular layers were typical of a mammal. This study therefore provides unique transition pattern in the four-striped mouse skin morphology different from the textbook description of the normal mammalian skin

Learning styles of physiotherapy students and teaching styles of their lecturers in undergraduate gross anatomy education

Background. Anatomy is essential to prepare physiotherapy students for future clinical practice. Student learning styles and lecturer teaching styles may influence learning outcomes. Objective. To determine if the learning style of this student population is consistent and compatible with lecturers’ teaching styles for better learning outcomes. Methods. A descriptive cross-sectional study was undertaken during 2015 and 2016. The Grasha-Riechmann learning style scale (GRLSS) and Grasha-Riechmann teaching style scale (GRTSS) were used to measure learning styles of two consecutive physiotherapy student cohorts and teaching styles of their anatomy lecturers, respectively. Results. Student samples were small (group 1: N=59 and group 2: N=54), but response rates high (n=39; 66.1% and n=43; 81.5%) in 2015 and 2016, respectively. Mean Likert scores for GRLSS indicated that the most popular choice for learning style was the dependent style (mean (standard deviation) 3.81 (0.75)) for group 1 and the independent style (3.68 (0.61)) for group 2. Female students preferred the dependent style (group 1: n=12; 30.8% and group 2: n=10; 23.3%) and male students the participant style (group 2: n=6; 14%) of learning. Lecturers scored highest in the expert category of teaching styles. Compatibility between learning and teaching styles was seen in both years based on comparisons made using teaching style clusters, where the identified GRLSS and GRTSS were grouped together and seen to fit into specific cluster categories. Conclusion. Consistency in learning style choice was observed. A degree of cohesion between student learning styles and their respective lecturers’ teaching styles augured well for good interaction between staff and students

Putative adult neurogenesis in old world parrots: the congo African grey parrot (Psittacus erithacus) and timneh grey parrot (Psittacus timneh)

In the current study, we examined for the first time, the potential for adult neurogenesis throughout the brain of the Congo African grey parrot (Psittacus erithacus) and Timneh grey parrot (Psittacus timneh) using immunohistochemistry for the endogenous markers proliferating cell nuclear antigen (PCNA), which labels proliferating cells, and doublecortin (DCX), which stains immature and migrating neurons. A similar distribution of PCNA and DCX immunoreactivity was found throughout the brain of the Congo African grey and Timneh grey parrots, but minor differences were also observed. In both species of parrots, PCNA and DCX immunoreactivity was observed in the olfactory bulbs, subventricular zone of the lateral wall of the lateral ventricle, telencephalic subdivisions of the pallium and subpallium, diencephalon, mesencephalon and the rhombencephalon. The olfactory bulb and telencephalic subdivisions exhibited a higher density of both PCNA and DCX immunoreactive cells than any other brain region. DCX immunoreactive staining was stronger in the telencephalon than in the subtelencephalic structures. There was evidence of proliferative hot spots in the dorsal and ventral poles of the lateral ventricle in the Congo African grey parrots at rostral levels, whereas only the dorsal accumulation of proliferating cells was observed in the Timneh grey parrot. In most pallial regions the density of PCNA and DCX stained cells increased from rostral to caudal levels with the densest staining in the nidopallium caudolaterale (NCL). The widespread distribution of PCNA and DCX in the brains of both parrot species suggest the importance of adult neurogenesis and neuronal plasticity during learning and adaptation to external environmental variations

Changes in the cholinergic, catecholaminergic, orexinergic and serotonergic structures forming part of the sleep systems of adult mice exposed to intrauterine alcohol

We examined the effect of chronic prenatal alcohol exposure on certain neuronal systems involved with the sleep-wake cycle of C57BL/6J mice exposed to prenatal alcohol once they had reached 56 days post-natal. Pregnant mice were exposed to alcohol, through oral gavage, on gestational days 7–16, with recorded blood alcohol concentration (BAC)s averaging 1.84 mg/ml (chronic alcohol group, CA). Two control groups, an oral gavage sucrose control group (chronic alcohol control group, CAc) and a non-treated control group (NTc), were also examined. At 56 days post-natal, the pups from each group were sacrificed and the whole brain sectioned in a coronal plane and immunolabeled for cholineacetyltransferase (ChAT), tyrosine hydroxylase (TH), serotonin (5HT) and orexin-A (OxA) which labels cholinergic, catecholaminergic, serotonergic and orexinergic structures respectively. The overall nuclear organization and neuronal morphology were identical in all three groups studied, and resemble that previously reported for laboratory rodents. Quantification of the estimated numbers of ChAT immunopositive (+) neurons of the pons, the TH+ neurons of the pons and the OxA+ neurons of the hypothalamus showed no statistically significant difference between the three experimental groups. The stereologically estimated areas and volumes of OxA+ neurons in the CA group were statistically significantly larger than the groups not exposed to prenatal alcohol, but the ChAT+ neurons in the CA group were statistically significantly smaller. The density of orexinergic boutons in the anterior cingulate cortex was lower in the CA group than the other groups. No statistically significant difference was found in the area and volume of TH+ neurons between the three experimental groups. These differences are discussed in relation to the sleep disorders recorded in children with fetal alcohol spectrum disorder (FASD)

Putative adult neurogenesis in two domestic pigeon breeds (Columba livia domestica): Racing homer versus utility carneau pigeons

Generation of neurons in the brains of adult birds has been studied extensively in the telencephalon of song birds and few studies are reported on the distribution of PCNA and DCX in the telencephalon of adult non-song learning birds. We report here on adult neurogenesis throughout the brains of two breeds of adult domestic pigeons (Columba livia domestica), the racing homer and utility carneau using endogenous immunohistochemical markers proliferating cell nuclear antigen (PCNA) for proliferating cells and doublecortin (DCX) for immature and migrating neurons. The distribution of PCNA and DCX immunoreactivity was very similar in both pigeon breeds with only a few minor differences. In both pigeons, PCNA and DCX immunoreactivity was observed in the olfactory bulbs, walls of the lateral ventricle, telencephalic subdivisions of the pallium and subpallium, diencephalon, mesencephalon and cerebellum. Generally, the olfactory bulbs and telencephalon had more PCNA and DCX cells than other regions. Two proliferative hotspots were evident in the dorsal and ventral poles of the lateral ventricles. PCNA- and DCX-immunoreactive cells migrated radially from the walls of the lateral ventricle into the parenchyma. In most telencephalic regions, the density of PCNA- and DCX-immunoreactive cells increased from rostral to caudal, except in the mesopallium where the density decreased from rostral to middle levels and then increased caudally. DCX immunoreactivity was more intense in fibres than in cell bodies and DCX-immunoreactive cells included small granular cells, fusiform bipolar cells, large round and or polygonal multipolar cells. The similarity in the distribution of proliferating cells and new neurons in the telencephalon of the two breeds of pigeons may suggest that adult neurogenesis is a conserved trait as an ecological adaptation irrespective of body size

Ultrastructural studies of acrosomal formation in the testis of male greater cane rat (Thryonomys swinderianus)

Purpose: In furthering the understanding of the process of spermatogenesis in the greater cane rat, this study describes the ultrastructural spermiogenic transformation and acrosomal formation in the testes of this hystricomorphic rodent that is currently undergoing domestication in parts of West Africa. Materials and Methods: Testicular samples were obtained from ten sexually mature cane rats that were perfused-fixed using Karnovsky\u27s fixative (phosphate buffered 2% paraformaldehyde – 2.5% glutaraldehyde fixative at pH 7.4). The samples were processed for ultrastructural analysis and examined under the transmission electron microscope. Results: The testes of the cane rat showed uniqueness in its cellular associations and the ultrastructure of the spermatogenic cells especially in the formation of the acrosome. The spermatid differentiation and acrosomal formation occurred in 12 steps with the first three steps being the Golgi phase and the next three steps making up the cap phase. While the three steps that follow constitute the acrosomal phase, the last 3 steps make up the maturation phase. At the cap and acrosomal phases, the entire acrosomal system comprising the vesicle and granule covers the head of the spermatids with no clear indentation of the nuclear surface by the formed acrosome. Furthermore, elongated spermatids at the maturation phase contained abundance of nuclear vacuoles. Conclusion: This work has not only provided information that will further the understanding of spermatogenesis but also aid the understanding of acrosomal reaction in the reproduction of the greater cane rat

Astrocyte morphology, heterogeneity, and density in the developing African giant rat (Cricetomys gambianus)

Astrocyte morphologies and heterogeneity were described in male African giant rats (AGR; Cricetomys gambianus, Waterhouse) across three age groups (five neonates, five juveniles, and five adults) using Silver impregnation method and immunohistochemistry against glial fibrillary acidic protein. Immunopositive cell signaling, cell size and population were least in neonates, followed by adults and juveniles, respectively. In neonates, astrocyte processes were mostly detected within the glia limitans of the mid and hind brain; their cell bodies measuring 32 ± 4.8 μm in diameter against 91 ± 5.4 μm and 75 ± 1.9 μm in juveniles and adults, respectively. Astrocyte heterogeneity in juvenile and adult groups revealed eight subtypes to include fibrous astrocytes chiefly in the corpus callosum and brain stem, protoplasmic astrocytes in the cortex and dentate gyrus (DG); radial glia were found along the olfactory bulb (OB) and subventricular zone (SVZ); velate astrocytes were mainly found in the cerebellum and hippocampus; marginal astrocytes close to the pia mater; Bergmann glia in the molecular layer of the cerebellum; perivascular and periventricular astrocytes in the cortex and third ventricle, respectively. Cell counts from twelve anatomical regions of the brain were significantly higher in juveniles than in adults (p ≤ 0.01) using unpaired student t-test in the cerebral cortex, pia, corpus callosum, rostral migratory stream, DG, and cerebellum. Highest astrocyte count was found in the DG, while the least count was in the brain stem and sub cortex. Astrocytes along the periventricular layer of the OB are believed to be part of the radial glia system that transport newly formed cells towards the hippocampus and play roles in neurogenesis migration and homeostasis in the AGR. Therefore, astrocyte heterogeneity was examined across age groups in the AGR to determine whether age influences astrocytes population in different regions of the AGR brain and discuss possible functional roles

Connective tissue, glial and neuronal expressions in testis of the African giant rat (Cricetomys gambianus)

Introduction: This study was carried out to investigate the expression of connective tissue (Collagens I and III), glia and neuronal markers in the testis of the African giant rat using histology and immunohistochemistry techniques. Materials and Methods: Eight (8) apparently healthy wild male African giant rats were used for this experiment, divided into 2 groups (juvenile and adult) of 4 animals each. The testes were harvested following intracardial perfusion of the rats and histology was performed using Haematoxylin-Eosin stain and Mallory-Heideinhain rapid one- step staining for connective tissue. Immunohistochemical identification was achieved using the following antibodies: anti-collagen type I, anti-collagen type III, anti-glial fibrillary acidic protein and anti-p75 nerve growth factor for the expression of collagen type I, collagen type III, astrocyte-like cell and neuronal cells respectively. Photomicrography was achieved using Axioskop® microscope and quantitative data were analyzed using student t-test. Results: The cyto-architecture of the testis was typical in the African giant rat. The connective tissue expressed in the juvenile and adult group, signaling of glial-like cells were seen in the perivascular region across the experimental groups. Immuno-localization of neuronal cells were seen in the interstitial spaces across all the groups, but with more expressions in the juvenile. Conclusion: This work has provided a clear description of the expression of connective tissue, neuronal and glial cells in the testis of the African giant rat and their possible relationships across juvenile and adult groups