The Human Adrenal Gland With Special Reference to the Vasculature

Abstract

SUMMARY The internal anatomy, particularly the vasculature, of the human adrenal was investigated with the help of three-dimensional reconstruction models supplemented by stereo-angiography. A definite pattern of positional relationship was shown to exist between the cortex, medulla and venous drainage, and on this basis the adrenal should be considered as a tripartite structure consisting of a head, a body and a tail region. The disposition of the longitudinal muscle bundles in the adrenal veins follows a definite pattern in each region of the gland. The muscular veins lie almost entirely within sleeves of cortical tissue. The selective gathering of the muscle bundles into the medulla-facing segment of the veins in certain regions of the gland is described. The effect of this muscular arrangement on the venous sinuses which pass between the muscle bundles was investigated and considered to be one of closure. Elastic tissue was demonstrated in the medullary venous sinuses; it is suggested that together with the muscle bundles both constitute a musculo-elastic organ capable of intermittent explosive release of hormones from the venous sinuses into the central vein. The hitherto neglected effect of the unique venous sytem on the function of the cortex was examined. Its possible role in the morphological changes of the adult cortex in response to stress, adrenocorticotrophic hormone, and in adrenal pathology is considered.

The Nature of the Venous Systems in the Adrenal Gland

“…The filling of the capsular veins appears to be mainly but not exclusively dependent on flow from the venae comites of the medullary arteries (Fig. 5) evidence to support the suggestion of Dobbie and Symington (1966) that the biosynthetic products of the zonae fasciculata and reticularis can exit via the veins or arteries rather than or in addition to the central vein is the demonstrated link between some inner cortical sinusoids and the venae comites of the medullary arteries (Fig. 5).…”

“…These descriptions give the impression that there is one circulatory system in the adrenal gland although this gland is composed of two district tissues. The present concern is with the pattern of venous drainage from the cortex and medulla and the investigation into the hypothesis that a portal system exists in both directions (Vogt 1944;Dobbie and Symington 1966).…”

“…Nor is it obvious why hypertrophy of the smaller radicles of the adrenal vein occurs in hypertension (Zecker 1935) and in contracted kidneys (Kashiwagi 1922) in which conditions one can establish that there is increased renal vasoconstriction and, on the other hand, hypertrophy can occur in toxic goitre (Zeckwer 1935) which is a disease characterized by an increased renal blood flow and hence reduced renal vasoconstriction. Dobbie and Symington (1966) observed that retrograde perfusion of the human adrenal is obligatory for in vitro biosynthetic studies but it is not possible on the current data to appreciate its relevance or to show how this perfusion can be, if at all, achieved in vivo.…”

“…Sasano et al (1971) reported difficulty in filling the sinu soids with a barium solution. The 'hold-up of blood at the cortico-medullary vascular dam', referred to by Dobbie and Symington (1966), is an artefact caused by insufficient wash out of red blood cells from the cortical sinusoids. Having successfully filled, in the current experiments, the venous system of the human adrenal gland, the essential constancy and similarity to that of the dog bcame apparent (Figs.…”

The appearance of the adrenal glands on computed tomography in multiple endocrine neoplasia type 1

“…To a lesser extent, a difference was also detected in adrenal body size. Dobbie and Symington (15) showed that the limbs of the adrenal gland consist predominantly of adrenal cortical tissue with little or no medullary tissue, which is maximal in the body. Enlargement of the limbs indicates adrenal cortical expansion and our study therefore confirms previous reports that adrenocortical hyperplasia is part of the MEN1 syndrome.…”