Preparation of highly purified porcine theca cells.

A novel method for purifying dispersed porcine theca cells, with less than 3% granulosa cell contamination, was developed by the repeated use of mechanical and enzymatic procedures. The steroidogenic criteria used for the identification and purity evaluation of both theca and granulosa cells were also improved. Purified theca and granulosa cells from medium-sized follicles displayed steroidogenic differences when they were cultured in the presence of 10% fetal bovine serum: (1) the theca cells synthesized oestradiol (239.1 +/- 35.1 pg ml-1 per 2.5 x 10(5) cells in 40 h), but the granulosa cells did not synthesize it unless aromatizable androgens were added; (2) theca cells synthesized androstenedione (73.2 +/- 14.4 ng ml-1 per 2.5 x 10(5) cells in 40 h), but granulosa cells did not; (3) FSH did not affect progesterone production in theca cells; (4) the theca cells secreted androstenedione for up to 48 h; and (5) FSH significantly stimulated progesterone production in granulosa cells during a culture for 40 h (P < 0.05), but not during culture for 12 h. The lack of response to FSH was used as a reliable, functional indicator of the purity of porcine theca cells. However, this criterion proved not to be useful for cells cultured for 12 h; porcine FSH had no effect on the progesterone production of theca cells co-cultured for this time with as many as 20% granulosa cells. However, after co-culturing for 40 h, this criterion resulted in the detection of only 3% granulosa cell contamination.(ABSTRACT TRUNCATED AT 250 WORDS)