Henry Gray (18251861). Anatomy of the Human Body. 1918.
in 30 mm. embryos. After birth the chromaphil organs degenerate but the paraganglia can be recognized with the microscope in sites originally occupied by them.
The paraganglia are small groups of chromaphil cells connected with the ganglia of the sympathetic trunk and the ganglia of the celiac, renal, suprarenal, aortic and hypogastric plexuses. They are sometimes found in connection with the ganglia of other sympathetic plexuses. None have been found with the sympathetic ganglia associated with the branches of the trigeminal nerve.
The aortic glands or bodies are the largest of these groups of chromaphil cells and measure in the newborn about 1 cm. in length. They lie one on either side of the aorta in the region of the inferior mesenteric artery. They decrease in size with age and after puberty are only visible with the microscope. About forty they disappear entirely. Other groups of chromaphil cells have been found associated with the sympathetic plexuses of the abdomen independently of the ganglia.
The medullary portions of the suprarenal glands and the glomus caroticum belong to the chromaphil system.
the Suprarenal Glands (Glandulæ Suprarenalis; Adrenal Capsule) (Figs. 1183,1184)The suprarenal glands are two small flattened bodies of a yellowish color, situated at the back part of the abdomen, behind the peritoneum, and immediately above and in front of the upper end of each kidney; hence their name. The right one is somewhat triangular in shape, bearing a resemblance to a cocked hat; the left is more semilunar, usually larger, and placed at a higher level than the right. They vary in size in different individuals, being sometimes so small as to be scarcely detected: their usual size is from 3 to 5 cm. in length, rather less in width, and from 4 to 6 mm. in thickness. Their average weight is from 1.5 to 2.5 gm. each.
Development.Each suprarenal gland consists of a cortical portion derived from the celomic epithelium and a medullary portion originally composed of sympatho-chromaffin tissue. The cortical portion is first recognizable about the beginning of the fourth week as a series of buds from the celomic cells at the root of the mesentery. Later it becomes completely separated from the celomic epithelium and forms a suprarenal ridge projecting into the celom between the mesonephros and the root of the mesentery. Into this cortical portion cells from the neighboring masses of sympatho-chromaffin tissue migrate along the line of its central vein to reach and form the medullary portion of the gland.
Relations.The relations of the suprarenal glands differ on the two sides of the body.
The right suprarenal is situated behind the inferior vena cava and right lobe of the liver, and in front of the diaphragm and upper end of the right kidney. It is roughly triangular in shape; its base, directed downward, is in contact with the medial and anterior aspects of the upper end of the right kidney. It presents two surfaces for examination, an anterior and a posterior. The anterior surface looks forward and lateralward, and has two areas: a medial, narrow, and non-peritoneal, which lies behind the inferior vena cava; and a lateral, somewhat triangular, in contact with the liver. The upper part of the latter surface is devoid of peritoneum, and is in relation with the bare area of the liver near its lower and medial angle, while its inferior portion is covered by peritoneum, reflected onto it from the inferior layer of the coronary ligament; occasionally the duodenum overlaps the inferior portion. A little below the apex, and near the anterior border of the gland, is a short furrow termed the hilum, from which the suprarenal vein emerges to join the inferior vena cava. The posterior surface is divided into upper and lower parts by a curved ridge: the upper, slightly convex, rests upon the diaphragm; the lower, concave, is in