 Reference Base  Gross and histological study on the thyroid gland of a we... |
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Talukdar, S.R., 1996. Gross and histological study on the thyroid gland of a week-old rhino calf (Rhinoceros unicornis). Indian Veterinary Journal 73 (January): 85-87, figs. 1-2
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| Location: |
World |
| Subject: |
Anatomy - Glands |
| Species: |
Indian Rhino |
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Rhinoceros unicornis. Thyroid collected from 7 day old calf in Gauhati Zoo. The two lobes of thyroid gland were flattered and triangular in outline. They were dark reddish brown in colour and existed at the ventro-lateral aspect of trachea, extending from second to the fourth tracheal ring. The two lobes were connected by slightly flat isthmus which was situated ventrally in between first and second tracheal rings. The present study recorded the weight, length, breadth and thickness of the right lobe of thyroid gland as 5.20 g, 3.5 cm, 2.8 cm and 1.0 cm and that of the left as 3.71 g, 3.5 cm, 2.5 cm, and 1.5 cm respectively. The isthmus measured 5.0 cm in rhino calf.
The present investigation revealed that the gland was covered by capsule which contained collagen, reticular and few elastic fibers. The connective tissue trabeculae from the capsule divided the gland into lobes, lobules and follicles. The present study revealed that reticular fibers were prominent around the follicular wall. The thyroid follicle of rhino calf measured 96 to 1145.4 m with an average of 228.32 m. The thyroid follicles of rhino call were lined by high cuboidal epithelium. But some small follicles and follicles in their course of development were lined by low cuboidal or squamnous cells. Cytoplasm towards the luminal border of follicular cells of rhino calf was more eosinophilic as compared to the basal part.
The follicular cells in hyperactive state of the gland were tall, in the process of mitosis, and the mass of the colloid was relatively small. Most of the follicules of rhino calf were also found in hyperactive state with depleted colloid, and in some cases the colloid near the follicular cell was more eosinophilic than the central part of the colloidal mass. Few follicles contained no colloid. The average epithelial height of follicular cells in rhino calf was 9.76 m.
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