Chapter II 

 GROSS ANATOMY 



The adrenal glands of mammals are compound organs de- 

 rived by the union of two originally separate types of tissue. 

 Because of their topographical relationship to one another 

 these tissues are referred to as cortical and medullary. These 

 expressions so commonly used in referring to the mammalian 

 adrenal are inappropriate when applied to the corresponding 

 tissues of the lower animals, and hence a nomenclature more 

 suitable from the point of view of comparative morphology is 

 desirable. We shall, therefore, refer to the cortex of the mam- 

 malian adrenal and its analogues in other genera as the in- 

 terrenal body or tissue, a term introduced by Balfour 28 in 1878. 

 Although a topographical term, this has the advantage, over 

 the expression, "cortex," in that it is correct for vertebrates in 

 general during the early stages of their development. We shall 

 refer to the medullary portion of the mammalian adrenal and 

 its analogue in other vertebrates as the chromaphil tissue, a 

 term introduced by Stilling 596 in allusion to the specific staining 

 reaction of this tissue when treated with chromates. Kohn 357 

 introduced the term "chromaffin" and Poll 508 the expression 

 "phaeochrome" to denote the same tissue. These expressions 

 frequently occur in the literature synonymously with the term 

 "chromaphil." 



The teleological significance of the particular relation existing 

 between the cortical and medullary portions of the adrenal is 

 still a matter of conjecture. Their independence in the early 

 stages of ontogeny is a repetition of the condition occurring 

 during phylogeny as indicated in the elasmobranch fishes where 

 the two elements remain separate. 



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