Different myosins in myoid and entodermal reticular epithelial cells of the thymus. An immunocytochemical study using specific antibodies against striated and smooth muscle myosin.

A sensitive immunofluorescence microscopical technique employing specific antibodies against highly purified actin and (smooth muscle type) myosin from chicken gizzard and myosin from human striated muscle was used to localize these contractile proteins in the thymus of rat, guinea-pig, cat and chicken. Myoid cells were seen to react with antibodies to striated, but not to smooth muscle type myosin, whereas reticular epithelial cells contained smooth, but not striated type myosin. Actin immunoreactivity was found in both myoid and reticular epithelial cells.