HISTOLOGY 43 



appearance 362 (cf. Figures 4 and 5). In the fetus and in the 

 accessory cortical bodies the cells usually all show a fascicular 

 arrangement (cf. Figure 6), without any tendency towards a 

 division into zones. In the oppossum (Trichosurus vulpecula) 

 the adrenal can not be divided into the conventional zones. 77 

 In many other species it is only by a stretch of the imagination 

 that one is able to differentiate the conventional zones. In 

 the monotremes, the glomerulosar type of arrangement is 

 found not only at the surface of the gland but also as islets in 

 the interior of the cortex. Differentiation of the cortex into 

 the conventional zones is not discernible in the members of 

 this order. 362 



The glomerulosa is poorly developed in many species as in 

 the rat (cf. Figure 4), the lemur (Lemur rufifrons), and monkey 

 (Cebus albifrons). In the lemur, the glomerulosa is completely 

 absent at certain parts of the gland, the fasciculata coming 

 directly to the surface at these points. On the other hand, 

 the glomerulosa is developed so well in the hedgehog (Erinaceus 

 europeus) as to be differentiable even macroscopically. In the 

 horse (Equus caballus) and giraffe (Camelopardalis giraffa) , the 

 glomerulosar cells are irregularly arranged in radial columns 

 for which reason this zone is often referred to in these species 

 as the "zona arcuata."™ 2 



In man the cells of the glomerulosa are small and round 

 (Figure 5). Each round mass of these cells is surrounded by 

 fine connective tissue with capillaries lying between them. In 

 women the glomerular zone is said to become hypertrophied 

 during pregnancy and to store up lipids so as to render it scarcely 

 differentiable in appearance from the fascicular zone. 123 The 

 glomerular layer of the human adrenal usually contains little 

 lipid, which, when present, exists in the form of fine droplets. 



The fascicular zone comprises the greatest part of the adre- 

 nal cortex. It varies in the arrangement of its cells from 

 strands of a single row of cells as in the rat (Figure 4) and bats 

 (Chiroptera) to thick strands comprised of many rows, as in 



