On the Interstitial Cells in Testicle of Guinea-Pig. 139 





No. of 



Duration 

 of 



Weight of the 

 animal 



Condition of testicle. 



1 



Protocol. 



experi- 

 ment. 



At 



beginning. 



At end. 



I 



73 



days. 

 54 



grm. 

 470 



grm. 

 495* 



Both testicles grown together. All semi- 

 niferous tubules with one stratum only. 

 Interstitial cells in a markedly increased 

 quantity. Sclerosation at the level 

 where the incision was made. 



II 



72 



109 



516 



670 



Right testicle : All seminiferous tubules 

 in the juvenile stage. Sclerosation 

 beginning at the level of the incision. 

 Very markedly increased quantity of 

 interstitial cells. 



Left testicle : Tubules in full spermato- 

 genesis with spermatozoa, tubules in the 

 stage of desquamation and with one 

 stratum only. Sclerosation as on the 

 right. Increased quantity of inter- 

 stitial cells. 



III 



60 



125 



130 



420 



Both testicles grown together. A great 

 number of seminiferous tubules in full 

 spermatogenesis ; others in the stage of 

 desquamation and with one stratum 

 only ; some tubules in the juvenile 

 stage. Quantity of interstitial cells 

 not increased. 



* The animal died of illness, and was weighed the last time nine days before its death. 



the two testicles of a normal animal, one will also sometimes observe very 

 striking differences in weight and in the development of the seminiferous 

 and interstitial apparatus. Great differences are also to be found between 

 two animals of the same litter. This is why it is often impossible to have 

 real control animals in experiments where conclusions should be based on 

 weight or age relations. 



On looking at fig. 4, one will see that there is a striking resemblance 

 between the condition of this testicle and the testicle of a young animal 

 (fig. 2). The condition of the seminiferous tubules, the condition of the 

 interstitial cells, and the distribution of the latter embedded in a granular 

 or homogeneous mass, all these remind one in a very striking manner 

 of the testicle of a guinea-pig of about 2 or 3 weeks of age, when the 

 testicle of this species has entered on its rapid development to spermato- 

 genesis and puberty. This juvenile stage of the testicle, which one can 

 observe under experimental conditions, is all the more interesting in that our 

 animal No. 72 was at the time of the operation fully grown, weighing 

 already more than 500 grm. There can be no more striking instance of the 



