Improved enrichment of functionally intact anterior pituitary cells by sequential centrifugal elutriation and density gradient sedimentation.

By centrifugal elutriation and subsequent Percoll density gradient centrifugation, we obtained highly enriched cell populations of the anterior pituitary of ovariectomized adult rats. Enrichment of somatotrophs, gonadotrophs and mammotrophs was 90%, 80% and 77%, respectively (determined by immunocytochemistry). 41% of the GH-cells showed a medium cell size and the highest density. 52% of the LH-cells and 44% of the FSH-cells were found within the population of the large and medium-dense cells. 69% of the prolactin-cells belonged to the small-sized cells with low density. Thyrotrophs were found within all of the size ranges. The majority of the corticotrophs (82%) showed a small cell size. The enriched somatotrophs, LH-gonadotrophs, and mammotrophs responded to GRF, LRH and TRH. Before and after enrichment, somatotrophs and mammotrophs showed the same responsiveness to releasing hormones. In contrast, enriched LH-gonadotrophs exhibited a higher responsiveness to LRH than unfractionated LH-gonadotrophs.