10 TADACHIKA MINOURA 



area numerous growing seminiferous tubules, having normal cell 

 arrangement and appearance. Mitotic divisions in the cells of 

 the seminiferous tubules are readily and frequently observable 

 in these testis grafts and their presence demonstrates beyond 

 doubt that an active growth of the seminiferous tubules had 

 occurred (fig. 6). Proliferation of endothelial cells of the stroma 

 between the tubules is also often observable. In some cases 

 around this new growth, that is, between it and the surrounding 

 mesenchymatous stroma, a sheath of connective tissue, resem- 

 bling the normal albuginea, had been formed (fig. A, sc). Study 

 of serial sections showed that the seminiferous tubules had 

 already assumed the convoluted form. 



In the case of ovary grafts, the growing area consists of numer- 

 ous foUicles, each composed of a central ovocyte surrounded by 

 a single layer of cuboidal granulosa cells, very much as in the 

 normal ovary (figs. 2, 3). 



4. Necrotic area. This consists mainly of a mass of necrotic 

 tissue, but there is no distinct boundary between this and the 

 preceding area. The size of the necrotic center varies in different 

 grafts. As the new growth is always due to a regeneration from 

 the original grafted piece of tissue, one finds, as a rule a gradual 

 transition from the center of the necrotic area to its periphery, 

 from necrotic to living tissue (fig. A, tt). Thus in testis grafts 

 one .end of a tubule will consist of living or regenerating cells, 

 while the other end terminates in a degenerating mass. The 

 necrotic changes involved in many cases pycnosis or karyorrhexis, 

 in other cases, karyolysis. The degree of necrosis developed in 

 the center of the graft is dependent of course upon the rapidity 

 with which a vascular supply to the graft develops. The slower 

 the estabhshment of vascular and nutritive connections between 

 the graft and the embryo, the more extensive are the necrotic 

 changes in the graft. In some cases the central tissue mass 

 was almost liquified and absorbed by phagocytosis, as was 

 demonstrated by the existence of giant-cells around the tissue 

 debris. Tke position and number of necrotic centers varies in 

 different grafts, and on this basis the grafts may be classified 

 as : monocentric, in which case the necrotic area may be either 

 centrally located or acentric, dicentric, and polycentric. 



