Comparative Histological and Histochemical Studies on the Pituitary Gland in the Egyptian Insectivorous Bat Rhinopoma Hardwickii (Gray, 1831) in Young and Adult Developmental Stages.

The pituitary gland is the primary endocrine gland, consisting of many cell types in its anterior region that regulate crucial physiological processes like development, maturation, metabolism, reproduction, stress response, and aging. This study aims to investigate and compare anatomical, histological, and histochemical variations between young and adult female pituitary glands of Rhinopoma hardwickii. The pituitary gland of ten healthy young and adult R. hardwickii has been used. Histological findings indicated that the gland in adult bats was irregular, whereas in young bats it was semicircular. Three types of cells appeared: acidophilic, basophilic, and chromophobic, which were unevenly distributed across the gland's body. Histochemically, chromophilic cells reacted positively with PAS and Alcian blue-PAS-Orange G stains. Also, using Masson's Trichrome stain, collagen fibers between the cells of adenohypophysis and in the capsule surrounding the gland gave a blue color. This study revealed several similarities as well as certain variations in the external shape of the anterior pituitary cells and their distribution pattern in both stages may be attributed to age-related developmental and physiological changes. Furthermore, the hormone cells of the anterior Pituitary were extensively specialized and became dedicated at after birth illustrating evolutionary adaptations to endocrine regulation.