448 THE DUCTLESS GLAXDS 



character ; in other cells they consist of a dense, almost solid, mass 

 of chromatin. The shape of the cell groups in the medulla varies 

 greatly; usually they form small spheroidal masses or short col- 

 umns. The cells are frequently arranged in a more or less tubular 

 form but without a distinct lumen. Frequently they surround a 

 minute capillary vessel. The medullary cells presumably pour 

 their secretion into the blood vessels, whose broad capillaries or 

 sinusoids (Minot *) permeate the delicate connective tissue bands 

 which inclose the cell groups. Felicine f claims to have demon- 

 strated the presence of minute intra- and intercellular secretory 

 canaliculi which open directly or indirectly through broader 

 lacunce, into the blood vessels. 



The cell groups of the medulla, like those of the cortex, are 

 divisible into the acidophile and the fatty types ; the former are 

 the more abundant, but the fatty metamorphosis is scarcely ever 

 so advanced as in the cortex. There is, however, great variation 

 in the size of the medullary cells. The larger ovoid elements form 

 the typical groups ; between these groups are narrow cell columns 

 consisting of much smaller and less highly acidophile cells, which 

 are arranged in slender columns and scattered irregular masses. 



In the vicinity of the central veins, small nerve trunks are 

 found, and occasional minute ganglia or isolated nerve cells occur 

 along their course. These are not to be confused with the large 

 ovoid epithelial cells of the medulla. 



BLOOD SUPPLY. The arteries which supply the suprarenal 

 glands form a plexus of vessels in the capsule of the organ and in 

 the neighboring connective tissue. Some of the smaller branches 

 of this plexus, the capsular arteries, supply the capsule itself, 

 others enter the organ and are distributed to the cortex and to 

 the medulla. The blood supplied to the capsular arteries, after 

 traversing the capillaries, enters small venules which are tributary 

 to the lumbar and phrenic veins. The course of the cortical and 

 medullary vessels has been exhaustively studied by Flint. 



The cortical arteries enter the zona glomerulosa where they 

 abruptly break up to form a capillary plexus which occupies the 

 connective tissue between the cell columns. Capillary vessels are 

 continued from this plexus through the intercellular connective 

 tissue of the zona fasciculata, where they are in intimate relation 



* Proc. Bost. Soc. of Nat. Hist., 1900. 



f Anat. Anz., 1902 ; also Arch. f. mik. Anat., 1904. 



\ Loc. cit. 



