The megakaryocytes are normal constituents of the bone marrow. These cells, or fragments of them, may be found in the peripheral blood of human beings and animals under physiological conditions. It has been reported that circulating megakaryocytes are more frequently seen in males than in females. In human beings, they are normally observed during the foetal stage, and less and less frequently in childhood and adult life. Megakaryocytosia, or the increased incidence of these cells in various tissues, has been observed in diseases such as myelosclerosis, myeloid leukaemia and inflammatory conditions, as well as after accidental or sudden death. Cirrhosis causes a reduction of megakaryocytes, even in the bone marrow. The incidence of circulating megakaryocytes is notably high in patients with cancer. Investigators in the field of cancer research have in the past frequently mistaken them for cancer cells. Then a more detailed study established a distinct morphological difference between the two cell types, and it was found that many so-called cancer cells were in fact circulating megakaryocytes. This, almost accidental, discovery drew attention to the biological importance of these cells in neoplastic disease, even if there are no bone metastases. It is not yet known why megakaryocytes are mobilized, and migrate from the bone marrow (myeloid tissue) to the blood, in malignant neoplasia. The present investigation was designed to determine whether megakaryocytaemia is in fact related to malignant disease and, if so, what factors cause and control it. Various causative factors have been suggested. They include stress, changes in the blood platelet level, anoxaemiai softening of the bone marrow, and a biological reaction to neoplastic tissue. It was therefore decided to study the incidence of circulating megakaryocytes in relation to the blood platelet level, stress, adrenalectomy, spenectomy and other experimental conditions. Hale Wistar rats were used in all experiments. For transplant tumours, Walker 256 carcinoma was injected subcutaneously in the right flank. Blood for the megakaryocyte counts was taken from the heart. The simple smear technique was considered inadequate for the purpose of this investigation, and a cytological technique was used instead.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:623085 |
| Date | January 1968 |
| Creators | Malaker, Kamalendu |
| Publisher | Imperial College London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/10044/1/15967 |
Page generated in 0.0368 seconds