SUPRARENAL GLAND—EFFECTS OF INANITION Daw 
the middle zone increase to an average diameter of about 7u. 
In relative volume, the nuclei of the outer part of the zone de- 
crease from about 33 per cent of the average cell volume at birth 
to about 10 per cent in the adult, while the nuclei of the inner 
part of the zone decrease from about 28 per cent to about 15 per 
cent in the adult. 
The nuclei of the inner cortical zone apparently decrease in 
average diameter from 6.1 u in the new-born to from 5 to 5.8 u 
thereafter. In relative volume, they decrease from about 28 
per cent of the average cell volume at birth to about 20 per cent 
thereafter. 
The nuclei of the medulla parenchyma cells increase in average 
diameter from about 6 uw at birth to about 6.7 u at three weeks, 
7.2 w at ten weeks, and 7.3 uw in theadult. In relative volume, 
they decrease from about 46 per cent of the average cell volume in 
the new-born to less than 10 per cent in the adult. 
Da Costa (713), in the suprarenal gland of the rat (Mus decu- 
manus), gives the following measurements for the nuclei: outer 
cortical zone, 4 xX 6 uw; middle zone, spherical, 6 «; inner zone, 
spherical, smaller. My data (previously cited) indicate a some- 
what larger average size for the‘nuclei of the middle zone. 
Canalis (’87) noted that, in general, the suprarenal parenchyma 
cells of both cortex and medulla are larger in the adult than in the 
young (rabbit, dog, guinea-pig). In the mouse Inaba (91) 
found the nuclei of medulla cells increasing in diameter from 
5.2 w in the new-born to 6 w at twenty-nine days and later. The 
cortical nuclei (near the corticomedullary boundary) showed a 
decrease in diameter from an average of 6.5 » in the new-born to 
5 » at twenty-nine days and later. This would indicate that 
there is an atrophic process of the inner cortical zone in the mouse 
corresponding to that found in the rat and other forms (to be 
discussed later). 
Mann (16) noted a seasonal change in the suprarenal cells 
(both cortex and medulla) of the gopher, which increase in size 
in the spring, with decrease later and during hibernation. 
THE AMERICAN JOURNAL OF ANATOMY, VOL. 25, NO. 3 
