OBJECTIVETo explore the methods of isolation, cultivation, purification, identification of the fetal mice testis Leydig cell and to observe its biological characteristics in vitro.

METHODSLeydig cells were isolated by 0.03% collagenase (type I) from fetal mice testis and cultured in DMEM/F12 medium. The identity and purity of Leydig cell were assessed by 3beta-hydroxysteroid dehydrogenase delta4-delta5 isomerase (3beta-HSD). Cell viability was measured by trypan blue. Testosterone level in the medium of cultured Leydig cells was measured in various culture phases and cell density by radioimmunoassay.

RESULTSThe purity of Leydig cell was (45.10 +/- 1.66)% before culture, and (81.17 +/- 2. 32)% 72 h after culture. The level of testosterone secreted by Leydig cells could be detected in the medium and its level was associated with the density and time of cultured Leydig cells. The secretion capacity of testosterone by single Leydig cell decreased gradually during the culturing period.

CONCLUSIONThe fetal Leydig cells isolated from fetal mice testis have high purity. It can be cultured and kept the secretion ability of testosterone for a few days in vitro. This system can provide a valuable model for further study on the cellular function of the Leydig cells of fetal mice.