Histological, and Transmission Electron Microscopic Investigation of Adrenal Gland of Iraqi Local Squirrel (Sciurus anomalous)


The adrenal gland is one the main endocrine gland, which is responsible for producing important hormones in relation to regulating functions of the nervous system, metabolism and balance of ions, and reproduction of the animals. The present study was designed to identify histological contents and structures of adrenal glands in the Iraqi wild squirrel. Electronic microscopic, routine and special stains were used to recognize the main cells and major histological structures. Twelfth healthy animals were dissected for this study following the animal ethics regulations of the college of veterinary, university of Al-Qadisiyah. The histological study identified that the adrenal gland has two main layers’ the medulla and cortex, also, the cortex has three layers including zona glomerulosa, zona fasciculata and zona reticularis. Cells of the cortex and medulla of the gland were negative with PAS stain, but Alcian blue was positive with cortex cells and negative with medulla. The features and distributions of cells of the cortex were in the zona glomerulosa was paved together cells and constituted a thin layer under the capsule, and zona fasciculata was extended as pillars in shape and a thicker layer of the cortex and zona reticularis, also medulla cells were clusters cells in shape and found in the centre of gland surrounded the central vein. Electronic transmission study was focused on the contents of cells, as a result, large secretory granules were detected as dark in colour and were very large amounts in zona glomerulosa, and zona reticularis, and a limited amount in zona fasciculata. Also, the medulla displayed many dense small secretory granules in the cytoplasm and limited moderately secretory granules. The cells of the layers’ cortex and medulla revealed that the nucleus was polyhedral in shape, but cells of zona fasciculata was single or diploid nuclei. Our finding concluded that special and routine stains clarified many structures of the adrenal gland, but electron transmission microscopic was the better technique to distinguish different types of granules in the adrenal gland of the squirrel