A freeze-etch study of occurrence of nuclear pores in normal and tumor cells

A freeze-etch study of nuclear pores performed on human lymphocytes, epidermal and corneal cells, on hamster fibroblasts, on rat and hamster sarcoma cells and cells from a human malignant melanoma, revealed that the frequency of pores as a part of very important biological cellular structures increases in proliferating cells, and that there is a statistically significand difference between normal and tumor cells. Once produced the pores maintain and their frequency practically does not change. The pores are randomly distributed on the nuclear envelope. Markham rotating method revealed an octa- or nonaedric outside shape of the pores and round inner margin with eight or nine granules. One bigger granule was found in the center of the pores. The granule is with a great probability filamentously attached to the margin of the pore. Fibrillar structures running to the pores on inner surface of nuclear envelope as far as the chemical composition of granules need special cytochemical examinations.