Vessels and Nerves of the Suprarenals 55 



The cell-protoplasm contains granules which vary in size and amount in 

 different cells (Carlier). Some of these granules are stained brown with 

 chromic acid and its salts (adrenalin or chromaphil reaction), and this gives 

 a yellowish-brown colour to the medulla when the suprarenals are fixed in 

 any solution containing these salts. Occasionally the colouration is more 

 diffuse. A similar reaction is sometimes given by the blood and lymph in 

 the vessels of the medulla in sections of the organ. 



Besides the chromaphil granules above mentioned, others are found, 

 somewhat coarser, soluble in water and alcohol but not in ether, and stain- 

 ing with difficulty. Lipoid and pigment granules may also occur. The 

 relationship of these various granules to one another is not known. 



Vessels and Nerves of the Suprarenals 



The blood-vessels are very numerous. The arteries enter at the surface 

 and give off branches to supply the cortex with a rich capillary network. 

 The blood-vessels do not penetrate the cell-columns of the zona glomerulosa 

 and zona fasciculata of the cortex, but run in the connective tissue septa 

 between them. In the zona reticularis the vessels become large, take on a 

 sinus-like character, and come into close relationship to the cells. They 

 pass into the sinuses of the medulla. According to Neumann, the blood- 

 supply of the suprarenal is more abundant than that of any other organ in 

 the body, viz., as much as 6 to 7 c.c. per gramme and per minute (with a 

 blood-pressure of 130 mm. Hg). This is even higher than that of the thyroid, 

 which comes next with 5 c.c. per gramme and per minute. The respiratory 

 exchange is also very high (Baumann). 



In birds and reptiles the suprarenals have a venous blood-supply as well 

 as an arterial — blood being conveyed to each gland by a "portal" vein 

 which is usually formed by the junction of two or three intercostal veins. 



The connective-tissue septa of the cortex contain lymphatics, which 

 pass directly into lymph- vessels of the medulla. 



The suprarenals are very richly supplied with nerves. Each receives no 

 less than thirty-three nervous filaments (Kolliker), derived in part directly 

 from the splanchnic, in part from the suprarenal plexus, which is itself 

 constituted by branches from the cceliac, phrenic, and renal plexuses. 

 After forming a network in the connective-tissue investment of the organ, 

 the nerves penetrate into the cortex, partly supplying its blood-vessels, 

 partly its cell-columns. But most of the nerves extend to the medulla, 

 where they form a dense plexus from which filaments pass to end between 

 the secretory cells. Groups of sympathetic nerve-cells are occasionally 

 found both in the medulla and in the deeper parts of the cortex. 



