Isolation of purified rat Leydig cells using continuous Percoll gradients.

Continuous, isoosmotic Percoll gradients were utilized to isolate highly purified (90-95%) Leydig cells from rat testicular interstitial cell suspensions. The purified Leydig cells were contained in the third of four bands generated on the gradient, and retained their morphological and biochemical integrity. The cells in the purified Leydig cell fraction stained positively for 3 beta-hydroxysteroid dehydrogenase activity, appeared characteristic of steroid synthesizing cells when examined electron microscopically, specifically bound 125I-hCG and responded to hCG stimulation in vitro by producing testosterone. This procedure for isolating purified Leydig cells has advantages over methods currently in use as the gradients are essentially isoosmotic throughout, are easily generated, relatively inexpensive to use, and are readily applicable to sterile procedures when cell culture is anticipated.