310 THE PHYSIOLOGY OF REPRODUCTION 



Reference has already been made to the fact that in the salmon 

 the material for the growth of the testis is supplied by the muscle 

 undergoing atrophy. The analogy existing between the glyco- 

 phosphoric acid which forms the " skeleton " of the nucleic acid, and 

 the glycerophosphoric acid which forms the skeleton of phosphorised 

 fats, suggests that the glycerophosphoric acid present in the muscle 

 as phosphorised fat furnishes the material from which the glycophos- 

 phoric acid bound up in the testis as the nucleic acid is formed. This 

 view is supported by the fact that, during the period of the growth 

 'of the testis, the blood of the salmon is exceptionally rich in phosphorised 

 fats, and that the tail of the spermatozoon is also very rich in 

 phosphorised fats. It would appear that ' these substances, after 

 having been transported to the testis, are there built up partly into 

 the nucleus of the spermatozoon, while part remains accumulated in 

 the tail of the spermatozoon as reserve material. 



Owing to their characteristic histochemical reactions the fate of the 

 lipoids in the testis can be followed to a certain extent. In the active 

 adult testis the interstitial cells are loaded with globules of lipoid 

 material. It is double-refracting in addition to staining with Sudan 

 and with osmic acid after bichromate, and is therefore not ordinary 

 neutral fat, but a mixture of ordinary fat with lipoids, such as lecithin 

 and cholesterin, similar to the mixture which is present in the adrenal 

 cortex or the corpus luteum. Similar globules are present also in 

 small amounts in the seminiferous tubules, where they show a regular 

 distribution in the spermatogonia, and more especially in the Sertoli 

 cells, 1 to which the spermatids are attached while undergoing 

 differentiation into .spermatozoa and from which they presumably 

 absorb the lipoids. From observations on human material Mott 2 has 

 drawn the significant conclusion that the interstitial cells are free from 

 lipoids until puberty, when active sperniatogenesis begins. The 

 importance of a normal metabolism of lipoids is further demonstrated 

 by the correlation which exists between abnormalities in the adrenal 

 cortex and the function of the testis. Hypertrophy of the adrenal 

 cortex is associated with sexual precocity. Conversely Mott has 

 found in cases of dementia praecox an atrophic adrenal cortex poor in 

 lipoids and associated with it regressive atrophy of the testis. The 

 writer 3 has found a similar correlation in the condition produced by 

 feeding animals on a diet free from vitamins. This leads to disturbances 

 in the distribution of the cortical lipoid of the adrenal and there is 

 also atrophy of the seminiferous tubules of the testis. 



1 Schafer, Text-book of Microscopic Anatomy, Longmans, Green & Co., 1912, 

 p. 622. 



2 Mott, " Normal and Morbid Conditions of the Testes from Birth to Old 

 Age in one hundred Hospital and Asylum Cases," Brit. Me<l. Jovr., 1919. 



3 Cramer, Unpublished observations. 



