Figure 1

Distinct MyHC-like proteins are expressed in different subsets of embryonic rat epidermal cells. Transverse cryosections of E18 rat lower hindlimbs were allowed to react with monoclonal antibodies raised against human skeletal muscle myosin and detected by immunohistochemistry. A. Antibody A4.840, which detects slow MyHC isoforms in developing skeletal muscle, reacts throughout the epidermis. B. Antibody N3.36, which detects several neonatal and adult fast MyHC isoforms in skeletal muscle, also detects antigen(s) in the basal cell layer of the epidermis. C. Antibody N2.261, which detects epitopes present on both neonatal slow and adult fast IIa skeletal muscle MyHC, reacts weakly in the basal cell layer of skin, but not in muscle at this age. D. Antibody A4.74, which detects adult fast IIa MyHC in muscle, is not reactive at this age in muscle or epidermis. E. Antibody A4.951, which detects adult slow skeletal MyHC and is therefore not expressed in muscle at this stage, is very weakly-reactive in basal epidermal cells. F. Antibody A4.1519, which detects MyHC(s) that are expressed in all fetal rat myotubes, does not detect epidermis. G. Antibody F1.652, that reacts with rat embryonic skeletal MyHC, is not reactive with embryonic epidermis. H. Antibody A4.1025, that detects all sarcomeric MyHCs, does not react with epidermis (arrow). All panels same scale. Muscle is visible in panels A, E-H and fibres are approximately 20 μm in diameter.