SUMMARY The current study was carried out on fifty specimens of the adrenal glands of male and female turkeys at 20 days, 6 months, 8 months, one year and 5 years of ages. The specimens were collected from the agriculture school at Sharkia province and fixed in 10% buffered neutral formalin, Ortha’s fluid, Zenker’s fluid, Helly’s fluid and 10% aqueous potassium iodate then they were subjected to processing till paraffin and frozen sections were obtained, stained histologically and histochemically. Also, they were fixed in a solution of 2.5 % glutaraldehyde and subjected to processing till the semi-thin sections were obtained, stained and examined with a JEOL JEM- 1010 transmission electron microscope operating at 80 kv. The anatomical findings: Revealed that, the adrenal glands of both sexes were small, paired organs lying in the abdominal cavity at the cranio-ventral poles of kidneys and just behind the lungs. Differences between the right and left adrenal glands were found in location, shape, size and weight. In both sexes, the right adrenal ranged from elongated to oval in shape with apex pointing caudally. While the left adrenals were pyramidal in shape, the glands were yellow in color. In early premature ages (20 days), the left adrenal glands in both sexes were partially covered by the gonads. In late premature ages (6 months) and in mature ages (8 months, one year and 5 years), the left adrenal glands were completely covered by the gonads. The weight of adrenal gland varied according to age and sex. The histological findings: Showed that, there were some differences in the cell’s arrangement of the adrenal glands in both sexes. The adrenal gland of males was characterized by a relatively thicker connective tissue capsule than females where the adrenal glands of turkey were invested in fibrous dense connective tissue capsule. The framework consisted mainly of dense collagenic fibers, reticular fibers and fine elastic fibers in connective tissue capsule. The pericapsular autonomic sympathetic ganglia were noticed. Each ganglion had multipolar nerve cells and numerous satellite neuroglia cells embedded in connective tissue entirely surrounding the capsule. The adrenal gland in both sexes at different ages was composed of two main tissue types; the cortical-like tissue (interrenal tissue) and the medullary-like tissue (chromaffin tissue). Both tissues were intermingled with each other. These glands were richly supplied with abundant blood sinuses, that were dist¬ributed among the cortical and medullary tissues. The sinusoids were wider in the center than there in the periphery. The cortical-like tissue or the interrenal tissue was homologous to the adrenal cortex and appeared acidophilic by H&E staining. It was arranged as cords and had a higher percentage volume than the medullary-like tissue which was arranged as islets. The cortico-medullary ratios varied with age and sex. The cellular arrangement of the cortical-like cells varied in the peripheral than the central region of the gland. Furthermore, the arrangement of the peripheral and the central cortical-like cells varied in both sexes at different ages, also the medullary-like tissue or chromaffin tissue was homologous to the adrenal medulla of mammals and arranged as islets. It was intermingled between the cortical-like tissue and distributed throughout the parenchyma where this was observed in both subcapsular and central zones and separated by blood sinusoids. The subcapsular zone was narrower and less numerous than that of the central medulla whose cells appeared basophilic by H&E staining but appeared brown by chromium salts in (Zenker’s, Helly’s and Ortha's fixatives). Two types of medullary-like cells were identified as: large cells with lightly stained nuclei and small cells with moderately darkly stained nuclei. Also, densely stained cells were frequently observed between the cortical and the medullary-like tissues and distributed throughout the gland. These cells were markedly increased at1- 5 years of age. They were observed as either single cells or in clusters. The shape of these cells varied from irregular to multipolar. The cytoplasm was densely basophilic which partially obscured the nuclei. The nuclei were elongated to spherical in shape. In addition, lymphoid tissue aggregations were noticed as different sized nodules. The histochemical findings: Revealed that, the cortical-like cells reacted positively with PAS while showed negative reaction with Alcian blue and this reaction increased with advancing ages especially in males. Also, the cortical like cells showed stronger positive reaction with Sudan black B reaction in females than in males. The cytoplasm of some cells within the medullary-like tissue showed coarse gray to brown positive granules. Also, the medullary- like cells were stained pale, light-green in females while dark-green in males with Giemsa. The ultrastructural findings: Clarified that, bundles of collagenic fibrils were found in the adrenal capsule. In females, at different ages, the peripheral cortical-like cells were situated parallel to each other and had large, polymorphic-shaped and centerally situated nuclei with superficial notches and undulating membrane. The nucleoli were single or double. The cell boundary was distinct. Numerous lipid droplets in different sizes were found, they gradually increased in number but decreased in size. They were rounded to oval in shape and appeared electron-lucent. Few, round to oval-shaped mitochondria were present, however, they were elongated (filamentous) in shape at 6 months of age. Mitochondrial matrix was moderately electron-dense and had tubular cristae at 20 days, but with vesicular cristae at 6 months and 8 months ages. Moreover, abundant free ribosomes and many dark lysosomes with high electron density were noted throughout the cytoplasm and gradually increased in number with aging in females other than the males. While the central cortical-like cells of females were polyhedral in shape and had the same characteristics of the peripheral cells but had fewer lipid droples and numerous mitochondria than in the peripheral cells in contrary to males. Mast cells were noticed in between the cortical-like cells. The medullary-like cells had a polyhedral shape, they contained large elongated nuclei and the nuclear membrane was distinct. The perinuclear space was distinct. The nucleoli were well-defined and prominent, sometimes polarized toward the nuclear membrane. Occasionally, one or two nucleoli per cell were observed. Abundant euchromatin and less heterochromatin were noticed. The cytoplasm had two types of cells including electron-dense granules of epinephrine-secreting cells and electron-lucent granules of norepinephrine-secreting cells. There were higher proportions of epinephrine-secreting cells than norepinephrine-secreting cells in females especially at eight months and one year of age than in males. Also, the densely stained cells were noticed in both sexes at one year of age. The cortical-like cells became more vacuolated in females at five years of age. Moreover, some cells showed pyknosis and apoptosis in both sexes at five years of age.