ABSTRACT
Information on the anatomical studies of the endocrine glands of the indigenous one-humped camel in Northern Nigeria is scarce, and the fact that these endocrine glands may be involved in the mechanisms of adaptation to hostile environment through which it survives for long periods without food and water in the arid zones. Thirty (30) one-humped camels, comprising fifteen (15) males and fifteen (15) females were used in this study. The animals were divided into 3 groups of 10 animals each. Group A, B and C constitute 10 one-humped camels (5 males and 5 females) aged between 1 to 5 years, 6 to 10 years and above 10 years, respectively. The gross anatomical study of the endocrine glands namely; thyroid, parathyroid and adrenal glands were done to determine their shapes, texture, color, surfaces, and borders, measurements on the weights where obtained using digital weighing balance, and measurements of width, thickness and length were taken using digital vernier caliper. Histological features were studied using routine Haematoxylin and Eosin (H and E) for light microscopy. Histochemical features of the endocrine glands were explored using Periodic Acid Schiff (PAS) special stain; for thyroid and parathyroid glands, Acid Hydrolysis Azure A for thyroid gland, Alcian blue and potassium dichromate for adrenal gland. Hormonal assays of Thyroid Stimulating Hormone (TSH), Triiodothyronine (T3), and Tetraiodothyronine (T4) were studied using three different Enzyme Linked Immuno Servent Assay (ELISA) Kits (obtained from Nazo Medical Diagnostic Services, Lagos) for the T3, T4, and TSH ELISA. The result showed that the thyroid gland was a paired-lobe, and lengthy organ, with blood supply from superior thyroid, middle thyroid and inferior thyroid arteries. Correlation of the weight of the thyroid gland in one-humped camel was directly proportional to the age of the animal, while the correlation of the concentration of the thyroid hormones (T3 and T4) was inversely proportional to the weight and the age of the vii thyroid gland in the indigenous one-humped camel. There were higher concentrations of thyroid hormones in the young than in the adult. Histological studies revealed the appearances of numerous vacuolated colloids, and apoptosis of the follicular cells of the adult animals, which highlight the reason for the above correlations. There were follicular and parafollicular cells. The parathyroid glands were two pairs of glands situated around thyroid gland lobes. In addition, accessory parathyroid glands were seen, in this study, situated on the right, while some on the left of the indigenous one-humped camel. The result showed that there was sexual dimorphism in the weight, length, width and thickness in the parathyroid glands in the juvenile age group and the young adult group, especially in the width, which was highly significant (P<0.01). The general histological features of the parathyroid gland consisted of densely packed chief cells (light and dark cells), oxyphil cells, and abundance of adipose cells in the adult male and female, but the adipose cells were absent in the young group. The right adrenal gland was positioned superior medial to the right kidney attached to the inferior medial surface of the liver, while the left adrenal gland was superior medially positioned within fat from the left kidney. There was sexual dimorphism in the weight and thickness of the adrenal gland of the female in the juvenile age group. Histologically, the adrenal cortex comprised of three zones generally, but four zones were seen in the young adult groups named; Zona glomerulosa, zona fasciculate, zona intermedia, and zona reticularis. Chromaffin cells of the medulla were identified by potassium dichromate chromaffin reactions. The results showed age and morphometric correlations, sexual dimorphisms and cellular morphology of the endocrine were pertinent to enhance the understanding of how the animal adapts to its environment, as this will provide baseline information for future related researches.
