A stable line of turkey bone marrow cells transformed by the myelocytomatosis virus strain MC31. Ultrastructural characteristics and localization of the DNA replication sites.

Attempts were made to characterize cells of the LSTC-SF2 line by scanning electron microscopy and transmission electron microscopy on the ultrastructural level. The virus-transformed cells are of oval, slightly elongated shape with an undulating surface. The cell nucleus is well outlined, poor in heterochromatin but with a strongly developed nucleolus. The cytoplasm is not rich in organelles except for an abundance of mitochondria with dense granules that are often found in them. With high-resolution autoradiography the DNA synthesis sites were identified mainly in proximity to the nuclear membrane and in the perinuclear spaces. The cells under study can be regarded as immature forms of the blood series and most likely as precursors of cells of the granulocyte or monocyte series.