256 Cc. M. JACKSON 
At eight weeks. The appearance of hematoxylin-stained sec- 
tions under low power is similar to that at three weeks. The 
cell structure in the outer and middle zones is also similar, with 
some increase in the size and number of lipoidal vacuoles, es- 
pecially in the outer half of the middle zone. The inner zone 
shows in general a more atrophic appearance, and occasional 
pigment cells occur for the first time. These are parenchyma 
cells containing one (sometimes two) irregularly spheroidal, 
light yellowish-brown, coarsely granular masses. As will be 
shown later, this pigment is probably a lipochrome. The 
nuclei of these pigment cells are irregular, sometimes central, 
sometimes crowded to the side of the cell and flattened. The 
inner zone cells bordering on the medulla are usually more or 
less flattened and atrophic in appearance. The medulla ap- 
pears similar to that at three weeks. 
At ten weeks to adult. At ten weeks, the histological struc- 
ture of the suprarenal (fig. 8) has reached practically the adult 
condition. In fact, although the gland increases in size, but 
few changes in structure are noticeable after the eight weeks’ 
stage previously described. In the usual hematoxylin-stained 
sections the structure appears as follows (fig. 8): 
The outer cortical zone (fig. 8. O) remains narrow, 6 to 12 
cells deep. It is somewhat variable in structure, with irregular 
cell cords separated by blood capillaries. The cells remain 
relatively small, with nuclei of variable form and structure. 
The cytoplasm is relatively scanty and somewhat granular. It 
contains a variable amount of lipoidal vacuoles, usually giving 
the cytoplasm a honey-comb appearance. The deepest cells, 
on the border between the outer and middle zones (fig. 8, 7), 
are relatively free from lipoidal vacuoles as found in the earlier 
stages. 
In the middle zone the only noteworthy change is in the 
amount of lipoids, as shown by the vacuoles. These increase, 
but to a variable extent. They are larger and more numerous 
in the outer half of the zone (fig. 8, Mo), but smaller and fewer 
in the inner half. In the larger cells of the outer part, the cyto- 
plasm presents a reticulated (honey-comb) appearance, like 
