Anatomical variations of the arterial supply to the adrenal gland in the rat

Abstract

The adrenal gland is an essential endocrine organ for the stress response. The functions of this organ may be studied by ligation of the adrenal artery or adrenalectomy. However, in prior studies, descriptions of the anatomical variations of the adrenal artery were insufficient and inconsistent. Therefore, anatomical variations of the arterial supply to the adrenal gland were studied in 18 male and 18 female Wistar rats by colored latex injection into the arteries. The vascularization pattern was categorized into 4 types based on the origin of each adrenal artery. The cranial and middle adrenal arteries arose from the caudal phrenic artery in Types 1-3, but the caudal adrenal artery emerged from the caudal phrenic artery in Type 1, from the renal artery in Type 2 and from the abdominal aorta in Type 3. In Type 4, the cranial and middle adrenal arteries stemmed from the cranial phrenic artery, and the caudal adrenal artery arose from the caudal phrenic artery. The number of adrenal arteries varied from 3 to 11 on the left side and from 4 to 12 on the right side, and the total varied from 9 to 20 (predominantly 14) in each individual. There was no sex difference in the vascularization pattern. The results show that more individual variations occur in the adrenal arteries of rats than was previously reported. Such variations should always be considered when experimental treatments of the rat adrenal gland are performed.

Fig. 1.

Schematic drawings of the branching pattern of the adrenal artery. A to C are for the left side, and D is for the right side. Ventral view. Abbreviations used in this figure and Fig. 2: AA, abdominal aorta; Ad, adrenal gland; Ca, caudal adrenal artery; CaPA, caudal phrenic artery; Cr, cranial adrenal artery; CrPA, cranial phrenic artery; Ki, kidney; Mid, middle adrenal artery; and RA, renal artery.

Fig. 2.

A: Photograph showing the arterial distribution pattern that is categorized as Type 1 on the right side. Ventral view. One cranial, 2 middle and 2 caudal adrenal arteries stem from the caudal phrenic artery. A': Schematic drawing of A. B: A photograph showing the arterial distribution pattern that is categorized as Type 2 on the left side. Ventral view. Two cranial and 3 middle adrenal arteries stem from the caudal phrenic artery, and 2 caudal adrenal arteries arise from the renal artery. B': Schematic drawing containing B, which is indicated by a gray outline in this scheme. For abbreviations, see the legend to Fig. 1.