506MORPHOLOGICAL AND HISTOLOGICAL STUDIES ON THE ADRENAL GLAND IN MALE AND FEMALE CHICKEN (Gallus domesticus)It was aimed to study the size and shape differences between right and left glands, the cortico-medullary ratio, cell size and nuclear diameters of the cortical and medullary tissues of the adrenal glands in Bangladeshi native chicken. Twenty chickens of 13 months old were collected from Sylhet sadar and Jaintiapur upazila of Sylhet district. After slaughter both right and left adrenal glands were collected aseptically from birds of either sexes and all of the gross morphology was measured. For the histological examinations, the tissue pieces from adrenal glands were collected and immersed in bouin’s fluid. After fixation, tissue samples were dehydrated, cleared, and embedded in paraffin. Haematoxylin and eosin staining method was used to examine tissue sections. The shape and weight of the gland were different from male to female birds. The adrenal parenchyma was composed of two main tissue types, the cortex and medulla; these were mixed throughout the organ. The columnar cortical cells with centrally placed nucleus were arranged in round or oval groups. The medullary tissue was composed of polygonal cells with round nucleus. The cortico-medullary ratio in male was 65.57% cortex and 34.43% medulla (1.9:1) and in female 58.84% cortex and 41.16% medulla (1.43:1). Medullary tissue of adrenal glands was more in female whereas the cortical tissue was more in male and this suggests that the adrenal medulla hormones production was more in female chicken and similarly, cortical hormone secretion was more in male birdsnbhowmik.gab@sau.ac.bdResearch592014Adrenal gland,Cortex,Cortico-medullary ratio,ChickenSonjoy Sarkar,Md. Nazrul Islam,Gitaindro Nath Adhikary,Bashudeb Paul,Nayan Bhowmik Department of Anatomy and Histology, Sylhet Agricultural University, Sylhet-3100, Bangladesh, Department of Anatomy and Histology, Sylhet Agricultural University, Sylhet-3100, Bangladesh, Department of Anatomy and Histology, Sylhet Agricultural University, Sylhet-3100, Bangladesh, Department of Anatomy and Histology, Sylhet Agricultural University, Sylhet-3100, Bangladesh,Department of Genetics and Animal Breeding, Sylhet Agricultural University, Sylhet-3100, Bangladesh