[Tissue culture studies on compensatory testicular hypertrophy of the young rabbit after hemicastration].

The regulation of compensatory testicular growth after hemicastration using prepubertal rabbits (less than 1000 g) was analyzed by weight increase of the remaining testis. At the 4th week postoperatively, the testis of hemicastrated rabbits weighed about 0.453 mg/g (testis weight/body weight) while the testis of sham operated rabbits weighed about 0.258 mg/g (testis weight/body weight). Thus, the testis of hemicastrated young rabbits developed compensatory growth up to about twice the size of control rabbit testis. This was further confirmed by the histological analysis of testes, in which the number of seminiferous tubules of hemicastrated rabbits was doubled as compared with the sham operated animal. The rabbit testicular cells obtained from the above operated testis could be cultured in monolayer form. These cultured monolayered cells were synchronized by culture in serum-free minimum essential medium (MEM) for 24 hrs. These primary rabbit testicular cells synthesized more DNA and RNA when cultured in a medium that contained hemicastrated rabbit serum, than in that containing normal serum. Stimulation of 3H-thymidine and 3H-uridine incorporation reached the maximum on the 4th day postoperation and thereafter DNA synthesis decreased rapidly whereas RNA synthesis decreased gradually. However, these cells cultured in MEM containing sham operated serum showed no significant increase in 3H-thymidine or 3H-uridine incorporation. Thus, the hemicastrated serum must contain a testis growth stimulating factor(s). Primary monkey testicular cells and primary rat testicular cells were treated with hemicastrated rabbits serum. The testicular cells of these animal species were insensitive to growth stimulation by the hemicastrated serum, which suggests that the testicular growth stimulation is species specific.(ABSTRACT TRUNCATED AT 250 WORDS)