60 ANATOMY 



placed from its original position by the migration of the repro- 

 ductive tract during embryonic development. Physiological 

 experiments as well as pathological observations are, however, 

 in accord with Aichel's conclusions. 



INVOLUTION OF THE ANDROGENIC TISSUE IN MAN 



The post-natal involution of the androgenic zone was first 

 described in 1911 almost simultaneously by Thomas, 626 Elliott 

 and Armour, 182 and Kern. 352 In the embryo of eight weeks 

 the adrenal lies anterior to and in contact with the kidney. 

 The two organs at this stage of development are of equal size. 

 The peripheral cells are filled with lipids and represent the 

 cells which will subsequently form the cortex of the adult 

 adrenal. The central part of the gland is composed of larger, 

 angular cells filled with granular cytoplasm. These cells which 

 are loosely arranged constitute the androgenic zone of the 

 adrenal. During most of the period of intrauterine develop- 

 ment, the true cortex remains as a comparatively thin rim of 

 closely packed small cells with deeply stained nuclei. The an- 

 drogenic zone grows rapidly and forms the main bulk of the 

 gland. At birth the true cortex has assumed its division into 

 definite zones. The androgenic zone begins to involute soon 

 after birth and this involution continues during the first years 

 of life. It is not until about the third year of life that the 

 gland assumes the characteristic appearance of the adult 

 gland. 123 



The androgenic zone in the new-born differs from the cortex 

 proper in several respects. It does not contain the characteris- 

 tic doubly refracting substance which characterizes the true 

 cortical tissue. It is characterized by an extremely abundant 

 vascular supply with some extravasation of blood. This ap- 

 pearance of hemorrhage has been attributed to injury during 

 birth but the existence of this hemorrhage in the adrenals of 

 newborn delivered by Caesarian section and during fetal life 

 demonstrates that it is not a result of injury. 376 



