Observations on the Shape of the Nucleus and its Determination

Abstract

Variations in the shape of the nucleus have been described in different animal cells. In addition, the following factors have been shown to be responsible for nuclear shape: (1) Surface tension : when this is equal over the surface of the nuclear membrane, the nucleus tends towards the spherical condition. When surface tension varies over the interface between nucleus and cytoplasm, nuclear polymorphism may result. (2) Mechanical deformation of the nucleus is common and may be due to various causes, chief amongst which are: (a) Pressure from cytoplasmic inclusions, e.g. fat, lecithin, and yolk; (b) Tonofibrillae; (c) in striated muscle, the influence of the Membranes of Krause which constrict the nucleus along its length--and limit its ends--by their prolongation from the myofibrillae into the sarcoplasm. (3) The centrosome, which has been shown (in the resting cell) often to repel that part of the nuclear membrane which is nearest to it. (4) The relation between cell shape and nuclear shape has been briefly discussed. It has been noted that the nucleus never comes into contact with the cell membrane, except in the rarest instances due to the intervention of mechanical factors. Evidence has been brought forward in favour of our view that there is a mutual repulsion between cell membrane and nuclear membrane. (5) Canaliculi and incisions in the nuclear membrane have been described in various cells. (6) The unfolding of such incisions during development and differentiation of some such cells has been described. (7) Intranuclear rodlets and their importance in the maintenance or the modifying of nuclear shape have been discussed. (8) Mitotic division and a certain degree of nuclear differentiation have been shown often to be incompatible--thereby accounting for amitosis in certain highly specialized nuclei. (9) The need for care in distinguishing between nuclear incisions and genuine amitotic division of nuclei has been emphasized.

Morphological risk assessment of cold atmospheric plasma-based therapy: bone marrow mesenchymal stem cells in treatment zone proximity

“…According to the literature, applying a force to the cell changes its elongation and orientation, which in turn induces deformation of the nucleus and changes its function [44,52]. Furthermore, deformation of the nucleus appears as a potential regulator of the genome function, with the effect that the cell shape information is carried through mechanical forces transmitted by the cytoskeleton to the gene expression [53]. As a consequence of cell shape deformation, the cytoskeleton produces a force to change the shape and size of the nucleus.…”

“…Therefore, the reason for the elongation of the cell and nucleus is the presence of a large number of free radicals and their effects on the cell and the consequent applied force on cytoskeletal actin filaments and myosin, which are supposed to control the morph ology of the cell and nucleus and can affect the expression of genes in response to changes in cell and nucleus shape. Cell deformation and cellular elongation ultimately lead to cellular damage and probably lead to cancer initiation due to the force exerted on actin fibers [52,53].…”

Nuclear mechanosensing of the aortic endothelium in health and disease

“…Mechanical forces profoundly influence cellular and nuclear morphology. The hypothesis that mechanical force can influence nuclear shape was posited by Champy and Carleton in the 1920s ( Champy and Carleton, 1921 ). Following this hypothesis, morphological adaptation of ECs to fluid shear stress was reported in the 1950s, and ECs were described to align in the direction of blood flow ( Altschul, 1954 ).…”

Electrodeformation of multi-bilayer spherical concentric membranes by AC electric fields

“…The nucleus is the control center of the cell, that is why we focus our attention on this organelle. Indeed, it has been shown that changes in cell shape results in modifications of nuclear shape and functions [7][8][9]. Cell shape changes in endothelial cells have been associated with nuclear shape remodeling [10] resulting in regulation of gene expression [11,12].…”