Spongiocytes

Spongiocytes are specialized steroid-secreting cells of the adrenal cortex, most prominently in the zona fasciculata, the middle layer of the adrenal gland. These cells are large and polygonal, and their cytoplasm has a foamy, spongy appearance due to numerous intracellular lipid droplets.

The primary function of spongiocytes is the synthesis and secretion of glucocorticoids, such as cortisol in humans. Secretion is driven by adrenocorticotropic hormone (ACTH) from the pituitary. Lipid droplets in the cytoplasm serve as cholesterol precursors for steroid production, and the cells contain abundant smooth endoplasmic reticulum and mitochondria with tubular cristae, reflecting their steroidogenic activity.

Histologically, spongiocytes are arranged in cords between a rich network of capillaries. The lipid-rich cytoplasm gives a characteristic pale, foamy appearance under light microscopy and contributes to the lipid storage and rapid steroid synthesis that characterizes the zona fasciculata.

In summary, spongiocytes denote the foam-like, steroid-secreting cells of the adrenal cortex’s zona fasciculata. Their lipid-rich cytoplasm, enzyme machinery, and regulatory relationship to ACTH support the production of glucocorticoids, integral to stress response, metabolism, and immune modulation.