HEMOGLOBIN BIOSYNTHESIS ENHANCEMENT FOLLOWING MITOCHONDRIAL-MEMBRANE GROWTH AND DIFFERENTIATION

1. A quantitative increase of organelles in early reticulocytes has been observed compared to that found in late erythroblasts of the peripheral rabbit embryo blood. 2. The increase is due to the formation of hemosomes, organelles taken as sites for final hemoglobin (Hb) biosynthesis or where the assembly of heme and globin polypeptides could occur. 3. These organelles derive indirectly from mitochondria whose internal membrane grows concomitantly to its differentiation, originating lamellated bodies that modify successively to prehemosomal vesicles, prohemosomes and hemosomes. 4. The occurrence of membrane synthesis for the formation of lamellated bodies could explain the increase of organelles per cell and, thereby, the enhancement of the Hb biosynthesis rate in peripheral embryo blood in relation to this biosynthesis rate in the liver, as had been biochemically ascertained by other authors.