Invited review: Adrenocortical function in avian and non-avian reptiles: Insights from dispersed adrenocortical cells

The Adrenal Gland of Squamata (Reptilia): A Comparative Overview

“…In non-mammalian vertebrates, the steroidogenic tissue is usually arranged in cords forming interconnected networks, without preferential organization. However, in birds and in some reptiles, just below the connective capsule, the cords of steroidogenic cells assume a ring or basket arrangement at the periphery of the gland, and parallel more deeply, suggesting a functional zonation, that has been observed in birds [8,46,47] and reptiles, in which the existence of several sub-populations of adrenocortical cells is supposed [8,48]. In mammals, the adrenal cortex is organized in an outer However, the chromaffin cells can also be studied with many other histological, histochemical and immunocytochemical methods [43,44]; for example, the NE cells can be identified through the immunopositivity to the enzyme, tyrosine hydroxylase (TH), converting L-tyrosine to L-3,4-dihydroxyphenylalanine (L-DOPA) (Figure 2), and by staining with Harris hematoxylin after treatment with citrate buffer at pH 6 [36].…”

“…In non-mammalian vertebrates, the steroidogenic tissue is usually arranged in cords forming interconnected networks, without preferential organization. However, in birds and in some reptiles, just below the connective capsule, the cords of steroidogenic cells assume a ring or basket arrangement at the periphery of the gland, and parallel more deeply, suggesting a functional zonation, that has been observed in birds [8,46,47] and reptiles, in which the existence of several sub-populations of adrenocortical cells is supposed [8,48]. In mammals, the adrenal cortex is organized in an outer glomerular zone, mainly producing mineralocorticoid hormones; a deep fasciculata zone, mainly producing glucocorticoid hormones, and an inner reticularis zone, mainly producing androgen hormones.…”

“…In birds, the adrenal gland may be two separate structures in contact with each other or a single median one. The steroidogenic tissue forms radially arranged cords mixed with blood vessels and chromaffin cell groups [8]. Finally, in mammals, the steroidogenic tissue forms the peripheral portion of the gland, called the cortex, surrounding an inner part formed by the chromaffin tissue, called the medulla, an arrangement allowing a considerable degree of mixing at the border between the two tissues (Figure 1) [1][2][3]7].…”