The enlargement of nuclei in damaged skeletal muscle and in severed tendons and nerves is reviewed. It is believed that a common factor in these different tissues is a decrease of extranuclear pressue leading to a secondary nuclear enlargement which in turn may result in nuclear division.

Sheath nuclei in twelve amputation neuromas and in three neurofibromas were measured. They were distinctly larger than the nuclei in the adjacent normal nerve segments. Some relations between amputation neuromas and neurofibromas are discussed. It is believed that in the former the nuclear increase is caused by a loss of pressure equilibrium, due to the severing of the connective tissue sheaths. It is possible that in neurofibromas some obscure weakness of the perineurium may be responsible for a similar loss of intraneurial but extranuclear pressure and thus for the ensuing nuclear enlargement and proliferation.


This work was supported by a grant from the Division of Medical Research, National Research Council, Canada.

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