The adrenal glands are paired abdominal endocrine organs vital to the bird's health.
The present research aimed to provide a comprehensive examination of the histological, ultrastructural, and immunohistochemical investigations of the adrenal gland in
Japanese quail during the post hatching period. The current study was performed on
21 healthy Japanese quail chicks at different post hatching periods. Our results
showed the adrenal gland is surrounded by a connective tissue capsule, which consists of dense collagen fibers containing large blood vessels, chromaffin cells, autonomic ganglia, fibroblasts, and migrating Schwann cells. The zonation of the adrenal
gland is composed of a subcapsular layer, a peripheral zone, and a central zone, which
gets more pronounced with age. At the ultrastructural level, the interrenal cells take
the steroid-secreting cells characters; they have varying amounts of lipid droplets
and abundant mitochondria. Adrenal medullary chromaffin cells showed positive
immunoreactivity to the NSE. With increasing age, the chromaffin tissue's Sox10
immunoreactivity increased. β-catenin is expressed within the plasmalemma and the
cytoplasm of the interrenal and chromaffin cells and its reactivity increased with age,
especially in the chromaffin cells. Our results indicate the adrenal gland undergoes
significant morphological changes during the postnatal life. Overall, the postnatal
period is an important time for the development and maturation of the adrenal
glands.

https://analyticalsciencejournals.onlinelibrary.wiley.com/journal/10970029