USA Surgery Today

Hematopoiesis in the human embryo and fetus can be divided into three overlapping phases: mesoblastic, hepatic, and myeloid (1). The earliest cells of erythroid lineage have been detected at day 14 of gestation within the blood islands of the yolk sac. By day 35, erythropoiesis occurs in the liver, and granulopoiesis and thrombocytopoiesis follow. Until 6 months gestation, the liver is the major site of hematopoiesis. The myeloid phase starts in the fourth month, when hematopoiesis, including monocyte and lymphocyte production, begins in the bone marrow. The bone marrow becomes the major site of hematopoiesis. Through early childhood, most of the bone marrow space is occupied by red (hematopoietically active) marrow. With age, the distal marrow spaces slowly fill with fat.

Plendil

Fetal erythrocytes differ from those produced in infancy and adulthood (Fig. 16-1: Plendil ). Differences in mean corpuscular volume, membrane properties, hemoglobin content, metabolic profile, and life span have all been well described. In the newborn infant, 70% to 90% of the hemoglobin is of fetal type, which is gradually replaced by adult hemoglobin during the next few months. Hemoglobinopathies characterized by abnormalities of the chain or embryonic or fetal hemoglobins result in abnormalities of the red blood cells at birth, but abnormalities of the (Plendil) chain of hemoglobin are detectable later in the first year of life. Because of the lower oxygen saturation of fetal blood, coupled with the relatively poor oxygen release to the tissues by fetal hemoglobin, the hematocrit is elevated in the immediate newborn period relative to later in infancy. The normal ranges for hematocrit, mean corpuscular volume, and reticulocyte count vary depending on the age of the patient, and it is important to consult a standardized chart of age-appropriate values (Table 16-1: Plendil). The leukocyte count and differential change markedly from birth to infancy to childhood and on to adulthood. Platelet counts remain stable from the birth of a full-term infant to adulthood.

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Plendil GN:Felodipine Extended Release Tab(feh LOW dih peen) BN:Plendil