Cell proliferation in bone marrow following surgical extraction of teeth: a pilot study.
- E Yücel
- The Journal of Nihon University School of…
A series of intraperitoneal calcium or magnesium chloride injections will stimulate mitotic activity in rat bone marrow and thymus tissue as will parathyroid extract by virtue of its ability to induce hypercalcaemia. Indeed, bone marrow mitosis is proportional to plasma calcium concentration. The reduction in cell division which thus accompanies hypocalcaemia can have dramatic consequences. Thymic and splenic atrophy and bone marrow hypoplasia all follow parathyroidectomy and there are impediments in liver regeneration after partial hepatectomy and in erythrocyte replenishment after haemorrhage (see reviews by Perris (6) and Whitfield e t al. (9)). It has also been shown in a variety of natural situations that a calcium-dependent control of mitosis operates when there is a physiological requirement for enhanced cell division in rat haemopoietic and lymphoid tissue. Thus, the altered patterns of mitosis which accompany changing body growth rates are paralleled by concomitant plasma ionised calcium fluctuations (6). A parathyroid-dependent hypercalcaemia also develops one or two days after haemorrhage in rats and this induces an increase in cell division in the bone marrow which thus speeds the restoration of the normal erythrocyte complement. Similarly in other heightened erythropoietic circumstances which occur after erythropoietin or cobaltous chloride administration or during pregnancy there again develops a parathyroid-dependent hypercalcaemia which stimulates bone marrow mitosis (6). Circadian variations in the proliferative activity of thymus and bone marrow tissue also seem to be linked to plasma calcium concentration changes. Most vividly this is seen between 16.00 and 20.00 h just before the onset of darkness when there are parallel decreases in calcium levels