Gross and microscopic anatomy of thyroid gland of the wild Africang rasscutter (Thryonomys swinderianus, Temminck) in Southeast Nigeria

ABSTRACT

The thyroid gland of the wild African grasscutter (Thryonomys swinderianus) was studied morphometrically and histologically by gross dissection. The organ was a symmetrical bilobed organ located on the lateral aspect of the trachea, between the first and the third tracheal rings, without an isthmus connecting the lobes. The mean weight of the two lobes was 0.23 ± 0.02 g and the relative thyroidbody weight was 0.03 ± 0.01 g/kg. The mean length (long axis), width (short axis) and thickness (height) were 1.50 ± 0.06 cm, 0.61 ± 0.05 cm and 0.42 ± 0.02 cm, respectively. The mean diameter of the small round follicles was 96.001 ± 0.03 µm, and that of the medium round follicles measured 180.18 ± 0.07 µm, while that of the large round follicles was 240.01 ± 0.08 µm. The epithelial cell heights of the small, medium and large-sized follicles were 7.52 ± 0.05 µm, 7.31 ± 0.01 µm and 7.12 ± 0.06 µm respectively. The general histologically appearance did not vary greatly from that described for most mammals. The small follicles were remarkably located centrally and the large ones were located peripherally. Peripheral vacuoles were present in the follicular lumen. The features and sizes of the follicular epithelial cells and the presence of parafollicular cells suggest activity in the thyroid gland of the wild African grasscutter (AU)

RESUMEN

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