Contracting striated muscle fibres differentiated from primary rat pituitary cultures.

Whole pituitaries or adenohypophyses alone of adult female Wistar/Furth rats were dissociated into single cells by means of two different enzymic disintegration methods. The single-cell suspension was then seeded out and cultured for up to 8 months in tissue culture dishes with untreated and polylysine-coated surfaces. The cells were cultured in different sera (horse serum, newborn-calf serum, fetal-calf serum, mixtures of horse and newborn-calf serum, and isogenic rat serum) and also in a serum-free, hormone-supplemented medium. When the cells were cultured in medium containing horse serum (15%) plus fetal-calf serum (3%) on polylysine-treated surfaces, cell fusion and the development of myotubes could be observed between day 5 and 10 after seeding and, on about day twenty, the formation of multicellular microstructures could be seen. Myotubes in such microstructures differentiate into muscle fibres, and show spontaneous contraction. Striation is visible both light and electron microscopyically. Such a differentiation into striated muscle cells depends on specific culture conditions: the serum used, the formation of microstructures, and the treatment of the culture dishes. There is apparently no previous report of striated muscle cells found in pituitary cultures.