GROSS AND HISTOLOGICAL STUDIES ON SOME LYMPHOID ORGANS OF THE GRASSCUTTER (Thyronomysswinderianus)

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Date
2014-06
Authors
KORZERZER, Rachel Mngu-suur
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Abstract
The present study analyses the gross and histological features of some lymphoid organs in the grasscutter. Twelve, apparently, healthy grasscutters,between the ages of three and seven months were obtained from Benue State and used for this study. The animals were transported in cages to the Department of Veterinary Anatomy, Ahmadu Bello University, Zaria where they were rested for 14 days before been sacrificed using chloroform inhalation anaesthesia. After dissection, the thymus, mesenteric lymph node and spleen were exposed, separated from surrounding tissue and photographed for gross assessment. Tissue samples were routinely prepared for histology using H & E as general histological stain and Rhodamine B-aniline methylene blue as special stain. Grossly, the thymus was bilateral on either side of the thoracic midline. Mean ± SEM values for thymic weights were 1.23 ± 0.048g, 0.53 ± 0.019g and 0.30 ± 0.042g at three, five and seven months of age, respectively. Histologically, the thymus showed loss of lymphoid cells as the grasscutters advanced in age.The spleen was dark red in colour, ovoid in shape and the size increased with age, having maximum value at seven months of age in both males and females. Mean ± SEM values for splenic weights were 0.67 ± 0.09g, 1.65 ± 0.35g and 2.31 ± 0.06g at three, five and seven months of age, respectively. The percentage ratio of splenic weight to body weight was 0.1%. The mesenteric lymph nodes were constantly bean shaped and appeared as opaque white masses which resembled fat, but were distinguished from fat by their consistent shape. The mesenteric lymph node weights were 0.056 ± 0.005g, 0.143 ± 0.034g and 0.1600 ± 0.023g at three, five and seven months of age, respectively.In conclusion, this study revealed that while the general morphologies of the thymus, spleen and mesenteric lymph nodes in the grasscutter are similar to that in other mammals, the relative amount of white to red pulp in the spleen showed some specie-specific characteristics, the thymus also showed a constant decrease in weight and size with advancing age, and at seven months there was no Hassal’s corpuscle and cortex-medulla distinction.
Description
A THESIS SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES, AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA IN PARTIAL FULFILLMENT OF THE REQUIREMENTSFOR THE AWARD OF THE DEGREE OF MASTER OF SCIENCE IN VETERINARY ANATOMY
Keywords
GROSS,, HISTOLOGICAL ,, LYMPHOID,, ORGANS,, GRASSCUTTER.
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