Microscopic anatomy of the subcommissural organ in the brain of the adult greater cane rat (Rodentia: Thryonomyidae)

Abstract

The subcommissural organ (SCO) is a well-developed gland present in the brain of vertebrates. The SCO secretes glycoproteins into the circulating cerebrospinal fluid and these assemble to form Reissner's fibre. It also plays an important function in neurogenesis and axonal guidance during embryogenesis. This study delves into the microscopic anatomy of the SCO in the adult greater cane rat (GCR), shedding light on its histoarchitectural characteristics. By utilizing histological techniques and microscopic analysis, we investigated the SCO's location and cellular composition within the brain of adult GCR. Our findings showed that the SCO in this species is located ventrally to the posterior commissure (PC) and dorsally to the third ventricle. The SCO consists of specialized ependymal or nuclear cell layer and apical processes lining the third ventricle. Moreover, the SCO's proximity to the PC and the third ventricle highlights its strategic position within the brain's ventricular system. With immunohistochemical analyses, the SCO cells expressed glial fibrillary protein when immunolabelled with Glial fibrillary acid protein (GFAP) antibody, a marker for astrocytes/astrocytic-like cells. Few microglia-like cells were immuno-positive for Ionized calcium-binding adapter molecule 1 (Iba1) antibody, that are existing within the SCO. However, the SCO in the GCR showed a negative immunostaining to NeuN antibody. This study contributes to our understanding of the microscopic anatomy of the SCO in a lesser-studied mammalian species. Further research into the SCO's functional significance especially during development in the GCR, may hold promise for more insights into neurological health and pathology.

Keywords: ependymal layer; greater cane rat; hypendymal cells; subcommissural organ.