566 f. a. e. crew and honor b. fell 



Description of an Undescended Testis of a Rabbit. 



The rabbit from which this testis was obtained was killed 

 at the ago of one year and seven months. The other testis 

 was scrotal and normal. On section the testis was found to be 

 degenerate and to contain a number of ovum-like bodies 

 similar to those described in the goat. 



General Structure of the Gonad. 



Seminiferous Tubules . — The seminiferous tubules are 

 small and degenerate. 



Epithelium. — The condition of the epithelium presents 

 considerable variation in different tubules. In some the cells 

 are comparatively normal and completely till the lumen. In 

 other tubules the cell-limits are indistinguishable except in 

 the peripheral layer, and the lumen contains a loose syncitium 

 of protoplasmic debris (PI. 20, fig. 11). Spermatogenesis appears 

 to have reached the spermatocyte stage and to have stopped at 

 that point. Most of the peripheral cells are typical spermato- 

 gonia. The more central cells are mostly large clear spermato- 

 cytes in various stages of synapsis. 



As in the goat the more central nuclei on the whole display 

 most degeneration. The nuclei of the peripheral spermato- 

 gonia are large, oval, and of a finely gi'anular structure, whilst 

 those lying farther in the lumen are of irregular shape, smaller 

 size, and are more deeply staining. In many cases the epithelial 

 cells are in active mitosis, but in the more central spermatocytes 

 the process does not appear ever to be completed. The nucleus 

 swells up to twice its original size and appears as a large clear 

 vesicle containing darkly-staining chromosomes or nuclear skein. 

 The chromatin material subsequently breaks do\\Ti into smaller 

 granules, and a further increase in the volume of the nucleus 

 is noted. Such degenerate nuclei have been found surrounded 

 by a mass of semi-fluid cell detritus, and in such cases would 

 appear to serve as centres around which intratubular bodies 

 are being formed (PI. 20, lig. 12). Several instances of pluripolar 

 mitosis were seen in the epithelium — a sign of degeneration. 



