Histomorphological and stereological study on the adrenal glands of adult female guinea fowl (Numida meleagris)

Adrenal gland is one of the most important glands of the endocrine system, located in the anterior pole of kidney and secretes important hormones that play roles in carbohydrate, water and electrolyte metabolism and maintain the blood pressure in birds. Since the available information regarding the histology and stereology of adrenal gland are limited, this study was conducted to determine the histomorphology and stereology of this gland. For this purpose, 8 adult helmeted guinea fowls were killed humanely and used. Their adrenals were removed and immersed in buffer formalin 10%. Then, tissue sections were prepared; staining with hematoxylin and eosin and green Masson’s trichrome and studied. Histological results showed that adrenal was composed of three layers: the subcapsular, peripheral and central layers. The subcapsular layer consisted of a thin layer of medullary cells while peripheral layer consisted of dominated cortical and small groups of medullary cells and finally the central layer consisted of cortical and dominant medullary cells. Sinusoids and ganglion cells were observed in all areas of adrenal. With the aid of stereological technique, the percentage of different parts of the adrenal was determined. In the right adrenal, cortex, medulla, capsule and sinusoids were 69/34%, 20/83%, 5% and 4/83% respectively and in the left adrenal, cortex, medulla, capsule and sinusoids were 71/16%, 20/16%, 4/68% and 4% respectively. Statistical analysis showed that in both glands, cortex has greater volume than medulla and there was no significant morphometric features differences between two glands.