Publisher Summary This chapter discusses the problems of adrenocortical structure using histochemical and ultrastructural techniques. In embryological development, adrenocortical cells arise from mesoderm, particularly from the columnar epithelial cells that line the coelom. Chromaffin cells have a separate origin, coming from neighboring paraganglion cells of the neural crest complex and thence migrating to lie adjacent to cortical cells. This intermingling is characteristic of most submammalian vertebrates though Elasmobranchii display complete separation. In Mammalia, the adult adrenal gland shows coalescence of chromaffin tissue and in Eutheria and Metatheria it lies centrally and is termed the medulla and eccentrically in the Prototheria. It is only over the past 10 years that the role of organelles in the biosynthesis of steroid hormones has begun to be delineated with correlated changes in fine structure. Changes occur in the smooth endoplasmic reticulum—the surface of which increases in area when the rate of steroidogenesis rises— and the mitochondrial cristae, which are usually tubular or vesicular in steroid secreting cells. Lamelliform cristae differentiate into tubular then vesicular cristae in most species studied. This is related to adrenocortical stimulation, for example, by ACTH. Thus, in hypophysectomized animals, the predominant tubular type is changed to vesicular by the administration of ACTH.

The Structure of the Mammalian Adrenal Cortex

The potential for contaminants to alter lipid or cholesterol dynamics in fish is rarely investigated and may include critical physiological endpoints that are impacted by exposure to endocrine-active substances. The current study investigated plasma and tissue lipid dynamics over a period of recrudescence in goldfish, while also examining the potential for β-sitosterol (β-sit), a phytosterol and 17β-estradiol (E2), an endogenous estrogen, to alter lipid homeostasis. Goldfish were exposed to 0 μg/g (no chemical; control), 200 μg/g β-sit (72.3% sitosterol mixture) or 10 μg/g 17β-estradiol (E2) via Silastic® implants for a period of five months. Plasma lipids peaked in control fish coincident with maximum liver size, while gonadal cholesterol concentration was highest concomitant with maximum gonad size. Plasma lipid concentrations were highly affected by E2 but not β-sit exposure; E2 elevated total cholesterol (p

Lipid dynamics in goldfish (Carassius auratus) during a period of gonadal recrudescence: Effects of β-sitosterol and 17β-estradiol exposure

Seasonal changes in in vivo cortisol response to ACTH and in plasma and pituitary concentrations of ACTH in a desert rodent, the sand rat (Psammomys obesus).

A.K. Sivashankar

Papers

Seasonal variations in cholesterol concentration in the testis, adrenal, liver and plasma of the Indian palm squirrel Funambulus pennanti (Wroughton).