THE EMBRYONIC DEVELOPMENT OF THE INTERSTITIAL 

 CELLS OF LEYDIG. 



BY 

 R. H. WHITEHEAD, M. D., 



Professor of Anatomy, Medical Department, University of North Carolina. 

 From the Hull Laboratory of Anatomy, University of Chicago. 



With 10 Text Figures. 



The interstitial cells of Leydig furnish such a striking feature in the 

 testis of mammalian embryos that one is surprised to find that their 

 development has received very little study. Doubtless this is due to 

 the fact that embryologists in their investigations of the development of 

 the testis have had their attention focused upon the much more important 

 subject of spermatogenesis. 



These cells have been known for a long time. Leydig discovered 

 them in 1850, and stated that they were a constant constituent of the 

 mammalian testis. He regarded them as connective-tissue cells, and 

 classed them with fat and pigment cells. This view was adopted by 

 Koelliker in 1854. Boll, 6g, observed an intimate relation between them 

 and the blood vessels, and believed that Leydig's cells composed the walls 

 of capillaries. Von Ebner, 71, studied them in several mammals, and 

 concluded that they were " a peculiar form of connective tissue." F. 

 Hofmeister, 72, seems to have been the first to approach the problem of 

 the nature of these cells by a study of embryonic material. Examining 

 the testis of human embryos at four and seven months, he found that 

 Leydig's cells constituted about two-thirds of the bulk of the gland in 

 the embryo of four months, and only about one-tenth in that of a boy 

 about eight years old; at puberty they were greatly increased in number, 

 and contained much fat and pigment. He too regarded the interstitial 

 cells as connective tissue, and thought that he could detect transition 

 forms between them and the fixed connective-tissue cells. Waldeyer, 74, 

 classed them with his plasma cells, but later regarded them as perithelial. 

 Harvey, 75, noticed, as others had done, their resemblance to nerve cells, 

 and advanced the view that they were derived from the sympathetic 

 nervous system. This view, however, has been discredited by all writers 

 on the subject. 



American Journal of Anatomy. — Vol. III. 



