Wool follicle matrix cell cultures were initiated as explants from Tukidale (carpet wool) sheep primary follicle bulbs after removal of the outer root sheath. Successful explantation required coculture on collagen with intact dermal papillae. Cells had a typical epidermal morphology (pavements of flattened. polyhedral cells). Extracellular matrix from dermal papillae, conditioned media, separation of dermal papilla from bulb matrices by tissue culture inserts and feeder layers were unable to support matrix cell explantation. Cultures could be maintained for up to 14 passages during which time the cells became larger with an increased cytoplasmic/nuclear ratio and irregular outline. Proliferation of matrix cells was greater on laminin than with either collagen type I or type IV. Proliferation was considerably reduced under serum-free conditions. This was most apparent at low calcium (0.09 mmol/L). By Northern hybridization matrix cells were found to express keratin K18 at all stages of culture. Keratin K 1.15 expression was evident by the tenth passage. The wool-specific keratin K2.10 was not detected. The data demonstrate that successful wool matrix cell culture is achievable. Keratin gene expression occurs in these cells and varies with the stage of culture.