248 J- J' Christian 



iiiques necessitate selection of appropriate sections and therefore require 

 serial sections, especially on animals with adrenals weighing less than 20 mg. 

 For glands heavier than this it is possible to select a portion through the 

 middle of the gland grossly. All these measurements can be made on sec- 

 tions stained routinely with hematoxylin and eosin. 



c. Adrenocortical sudanophilia. Fat stains, such as Sudan IV, are useful 

 in evaluating the secretory activity of the adrenal cortex. The normally 

 active cortex ("resting cortex") usually exliibits marked sudanophilia of 

 the fasciculata and glomerulosa with the fat in vacuoles of moderate size. 

 The sudanophilia becomes markedly reduced in acutely stimulated glands, 

 and upon continued stimulation the sudanophilia may return to some 

 degree, but the size of the vacuoles is reduced. Upon cessation, sudanophilia 

 becomes intense and the vacuoles large. Sudanophilia may be completely 

 absent from some species, such as the hamster, under all conditions. These 

 details are discussed in greater detail elsewhere (Dempsey, 1948; Sayers 

 and Sayers, 1949; Greep and Deane, 1949a, b; Symington ct al., 1958). 



d. Adrenal ascorbic acid declines on stimulation with ACTH, and this has 

 been used as a means of assaying ACTH in blood and other fluids (Sayers 

 and Sayers, 1949; Greep and Deane, 1949b). In general adrenal ascorbic 

 acid is a useful histochemical means of assaying adrenal stimulation, al- 

 though it may not reflect cortical secretory activity in the intact animal 

 (Slusher, 1958). 



e. Adrenal cholesterol also declines on stimulation and can be used to 

 assess cortical activity (Dempsey, 1948; Sayers and Sayers, 1949; Greep 

 and Deane, 1949b) . IVIeasurement of adrenal steroids in the adrenal venous 

 affluent, plasma, or their urinary metabolites can be used to assess cortical 

 activity directly. These are subject to daily variation and also respond 

 rapidly to stimulation. In addition, they are involved techniques to carry 

 out properly. There is also some question concerning the biologic signifi- 

 cance of the particular steroids measured. These measurements are there- 

 fore of limited use for investigations outside the laboratory and are subject 

 to numerous pitfalls in dealing with species which cannot be handled in the 

 laboratory without stimulating adrenal activity. Measurements of urinary 

 corticosteroids when practical and appropriate would probably be more 

 useful than blood levels for studies relating to mammalian populations. 

 Measurement of the products of corticosteroid metabolism in the urme is 

 somewhat intermediate between weight and direct functional measure- 

 ments, such as plasma steroids as a measure of chronic cortical stimulation. 

 Urinary steroids may be collected daily ad infinitum under laboratory 

 conditions and are unquestionably ^'ery valuable. However, steroid deter- 

 minations are complex and difhcult to interpret, and in the last analysis 

 represent only those steroids which escape as such via the urine and consist 



