Laminin-induced process outgrowth from isolated fetal rat C-cells.

A method for isolation of C-cells from rat fetuses was developed, and the morphological plasticity of the cells in primary culture systems was tested. Thyroid-parathyroid-ultimobranchial body (UB) complexes from 16-day rat fetuses were treated with 0.1% collagenase and 1000 PU/ml Dispase at 37 degrees C for 1 h. After dissociation by pipetting, UBs were obtained as remaining cell aggregates with diameters of 150-200 microns. The isolated UBs were cultured on untreated, fibronectin-coated, or laminin-coated substratum in Dulbecco's modified Eagle's medium/Ham's nutrient mixture F-12 (1:1) supplemented with 5% fetal calf serum. In some experiments, the medium was changed to serum-free medium after 24 h of incubation, until the UBs had formed cell sheets. At Day 4 in vitro, the cultures were subjected to immunostaining using anti-calcitonin antiserum. On untreated or fibronectin-coated substratum, most of the C-cells exhibited polygonal or ovoid shapes, and 5-8% of them were found to project processes. On laminin-coated substratum, the ratio of process-bearing C-cells to total C-cells was 23% in serum-supplemented medium and 51% in serum-free medium. The longest processes reached 150 microns in length. The processes were intensely reactive with anti-alpha-tubulin antibody and were completely disintegrated by colcemid, suggesting that the microtubule cytoskeleton participated in the maintenance of the processes. Thus it was demonstrated that fetal rat C-cells are still responsive to environmental signals, such as laminin, and extend neuritic processes.