Studies on the Bone Marrow of Premature Infants

Part I. Bone Marrow Pictures of Premature In fants

Abstract

Bone marrow studies on 53 premature infants as to the total numbers of nucleated cells and megakaryocytes, and as to the pictures of the bone marrow and megakaryocytes yielded the following results:
1) The number of nucleated cells showed a temporary decrease followed by a gradual increase during the first three days of life. This total increase in nucleated cells was particularly obvious after the fourth week of life.
2) The myeloid cells, forming 52-62% of the bone marrow cells, were greater in number than the lymphoid cells during the first three weeks of life. The myeloid and lymphoid cells numerically intersected at about the fourth week, after time the lymphoid cells became numerically greater to form 55-60% of the bone marrow cells.
3) The monocytes showed no significant percentage changes durin g the first two months of life, but the absolute number of monocytes increased after the third week of life in correlation with the total number of nucleated cells.
4) Myeloblasts comprised 2.5-4.0% of the bone mar row cells during the first week and decreased gradually to 1.0-2.0% at the fourth week.
5) Promyelocytes, myelocytes, metamyelocytes, a n d neutrophilic granulocytes decreased in percentage by the fourth week of life.
6) By means of the formula, A= myeloblasts+promyelocytes + myelocytes+metamyelocytes/band granulocytes + segmented granulocytes it could be clearly seen that the myeloid cells in the bone marrw of premature infants showed relatively high values until the fourth week of life.
7) The ratio of myeloid cells to erythroid cells Bmyeloid cells erythroid cells B=myeloid cells/erythroid cells was highest on the tourth day of life (5.4). Generally speaking, erythropiesis was rather hypoplastic, and the average value of B was observed to be 27.3%.
8) Megakaryocytopenia could not be noticed during the first two weeks, but an impeded maturation of the megakaryocytes was recognized.0-type megakaryocytes without thrombocytes were greater in number up to the second week. The number of megakaryocytes rapidly increased after the third week followed by megakaryocytic maturation. The numbers of megakaryocytes with thrombocytes and megakaryocytes without thrombocytes became equal at the third week of life, and after the fourth week, those without thrombocytes became again greater in number. From the above mentioned results, it was concluded that megakaryocytic development is premature in the neonates, especially so in the premature infants.