ENDOCRINE GLANDS 27 



spite of the transverse striation, these cells are not in any way 

 related to striated muscle ; they are certainly modifications of the 

 reticulum. Indeed, it is sometimes possible to observe a striped 

 appearance even in the degenerate cells of Hassall's corpuscles. 



No certainty is possible as to the origin of the eosinophilic 

 granular cells which are always present in the thymus. It is 

 tempting to believe that they, like the small cells or lymphocytes, 

 arise from undifferentiated mesenchyme, but there is more likeli- 

 hood that they represent immigrated blood cells. 



ADRENALS 



Like all the endocrine organs much attention has recently been 

 devoted to the suprarenal glands, and although there are no very 

 striking advances to record, steady progress has occurred. It is 

 particularly in connection with pathological changes that our 

 knowledge has recently been enriched. Simple enlargement in 

 size is quite commonly found accidentally at autopsy, and little is 

 known as to its significance, but nodular tumours, innocent or 

 malignant, may be the cause of remarkable changes in the 

 secondary sex characters. A child, obviously a female at birth, 

 may develop the hirsuties of the male, and may even present 

 enlargements of the reproductive organs reminiscent of the 

 external genitalia of the other sex. It appears that only neoplasms 

 of the cortex have this effect ; little or nothing is known of 

 medullary tumours of the adrenal. 



That there is a close dependence of cholesterol metabolism on 

 the adrenal cortex cannot be doubted, and there is evidence that 

 the regulation of this process is the work of the cells in the outer 

 seven-eighths of the cortex. The innermost part appears to be 

 concerned with the regulation of sexual function, particularly with 

 the development of the secondary sexual characters. Another 

 indication of the close relationship of the adrenal cortex to the 

 sexual functions is shown by the occurrence of histological changes 

 during pregnancy. Thus there is degeneration of the zona 

 reticularis, with slight hyperplasia of the other two layers. There 

 is also formation of a new stratum termed the zona gestationis. 



It is, however, quite possible that these alterations result from 



