An educational infographic and diagnostic image composite illustrating the anatomy and functional histology of the adrenal gland. On the left, a schematic diagram depicts the adrenal gland situated on the superior pole of the kidney. A high-magnification histological section (Hematoxylin and Eosin stain) of a macaque adrenal gland is featured in the center, showing the distinct layered architecture. The image labels the adrenal cortex and its three functional zones from superficial to deep: the zona glomerulosa (mineralocorticoids/aldosterone), the thickest layer, zona fasciculata (glucocorticoids/cortisol and corticosterone), and the zona reticularis (androgens/dehydroepiandrosterone). The innermost region is identified as the adrenal medulla, responsible for secreting catecholamines (epinephrine and norepinephrine). The histological section displays characteristic cellular morphology, including the rounded clusters of the glomerulosa, the linear cords of the fasciculata, and the branching network of the reticularis. This graphic is designed for medical education to correlate anatomical structure with endocrine function.

A pathophysiology diagram illustrating the bidirectional neuroendocrine axis between the brain and the adrenal gland, specifically focusing on the mechanisms of adrenarche. The diagram depicts a sagittal view of the human brain connected to an adrenal gland through several pathways. The adrenal gland is shown in cross-section with its histological zones: the medulla (Med) and the cortex, comprising the zona glomerulosa (ZG), zona fasciculata (ZF), and zona reticularis (ZR). Key pathways include: (1) Descending hypothalamic-pituitary-adrenal (HPA) influences via ACTH or unidentified corticotrophs; (2) Autonomic innervation from the spinal cord via the splanchnic nerve (Sp. n.) to the medulla and cortex; and (3) Ascending feedback loops where DHEA[S] and 11-oxyandrogens impact the CNS, potentially influencing mental health, puberty preparation, and sexually dimorphic behaviors. A separate feedback line shows cortisol's influence on the brain. The illustration highlights the complex interplay of endocrine, paracrine, and neural signals that regulate the maturation of steroidogenesis within the adrenal zona reticularis.

Imaging modality: Light microscopy of adrenal gland tissue, Hematoxylin and Eosin (H&E) stained section, viewed under brightfield illumination at high magnification (approximately 400x). Anatomical location: adrenal cortex with zona reticularis occupying the deepest corticoid layer, immediately superficial to the adrenal medulla, behind zona fasciculata. Visual features: cells arranged in anastomosing cords and small nests; cytoplasm is acidophilic and granular; nuclei are round to vesicular with prominent punctate nucleoli; capillary sinusoids are intermixed, producing a lobular vascular network. The zona reticularis lies between the zona fasciculata and the medulla, forming a reticular, fine meshwork. The cellular morphology indicates steroidogenic chromaffin-adjacent cells with robust endoplasmic reticulum and lipid-poor cytoplasm relative to fasciculata. Notable features include tight cell-to-cell contacts, vascularized stroma, and delineation from the surrounding zones. Pathophysiology/diagnostic significance: Normal zonation of the adrenal cortex is demonstrated; zona reticularis is responsible for glucocorticoid and sex hormone synthesis (androgen precursors), contributing to the endocrine milieu. Clinical relevance: understanding this histology supports differential diagnosis of adrenal cortical neoplasms and endocrine disorders; potential use in educational contexts, research on steroidogenesis, and histopathology training. This image serves as a reference for adrenal cortical anatomy, steroidogenic cell morphology, and the interface with the medulla.

Imaging modality: Light microscopy; Technique: Hematoxylin and Eosin (H&E) stained paraffin section showing adrenal gland architecture. Adrenal gland composed of an outer cortex with three concentric zones—zona glomerulosa (outermost), zona fasciculata, and zona reticularis—surrounding an inner medulla with chromaffin cells; in this low-power view the medulla is centralized and encircles the principal blood vessels near the image center. The cortex thickness measures approximately 1 mm in healthy adults and demonstrates dense cellular cords with alternating light and dark staining patterns corresponding to zona fasciculata foamy cytoplasm and zona glomerulosa compact arrangement; zona reticularis forms a network of intertwining cords. The medullary region consists of chromaffin cells arranged in irregular clusters with abundant cytoplasm and consistent purple nuclei; scant interstitial connective tissue is visible. The overall architecture is preserved, with no evident cortical hyperplasia, nodularity, or adrenal neoplasm. The specimen likely represents a normal, non-pathologic adrenal gland from a healthy adult, matching reported averages: combined gland weight ~8 g and normal cortex thickness ~0.7–1.3 mm. Diagnostic significance: confirms typical zonation and corticomedullary organization; pathology considerations would include hyperplasia, adenoma, pheochromocytoma if architecture were disrupted. Clinical correlation: adrenal function tests, cortisol/aldosterone regulation, catecholamine synthesis would be interpreted against this baseline.