SOME MORPHOLOGIC AND KINETIC STUDIES OF THE DEVELOPING ERYTHROID CELLS OF THE COMMON GOLDFISH, CARASSIUS AURATUS

Abstract

ABSTRACTDeveloping erythroid cells of the goldfish Carassius auratus were obtained from kidney prints and from smears of the peripheral blood. All preparations were stained with the May‐Grunwald Giemsa technique. Developing cells were divided into six different stages. The criteria used to stage the cells were degree of chromatin condensation, degree of basophilia, nuclear:cytoplasmic ratio, and cell shape. The morphology of the maturation sequence for erythroid cells in this organism was similar to that found by other workers in other non‐mammalian vertebrates.Fish received intraperitoneal injections of tritiated thymidine, tritiated uridine or tritiated leucine so that the stages involved in DNA synthesis, RNA synthesis and protein synthesis could be determined by means of autoradiography. For the tritiated thymidine studies the per cent labeled cells per stage from four different series receiving 0.5, 1.0, 3.0 or 6.0 μCi/g body weight were pooled, since subjecting the average per cent labeled cells per stage at the lowest and at the highest dosages to Student's t‐test showed no significant differences. In all four series the fish were killed 2 hr, 12 hr and daily, 1–8 days post‐injection. The 3H‐TdR studies showed that stages I‐IV were engaged in DNA synthesis; they also showed that about 5 days were required for the stage V cell to become a mature erythrocyte (stage VI cell).Tritiated uridine was injected at a dosage of 5.0 μCi/g body weight and animals were killed 1/2, 1, 3 and 6 hr post‐injection. Grain counts showed that stages I‐IV are engaged in RNA synthesis and that the rate of this synthesis decreased as maturation proceeded.Tritiated leucine was administered at a dosage of 5.0 μCi/g body weight, and fish were killed 45 min and 3 hr post‐injection. Grain counts indicate that stages I‐V are engaged in the synthesis of protein (assumed to be globin). The fact that DNA and RNA synthesis ceased with stage IV cells while protein synthesis continued into stage V cells indicated that the mechanism responsible for protein synthesis in stage V cells was produced at an earlier stage and was self‐sustained for about 5 days.