THE EFFECT OF X-IRRADIATION ON EMBRYONIC HEMATOPOIETIC TISSUES
A total of 581 guinea pig embryos were used to investigate the effect of x rays on developing hematopoietic tissues. The irradiated embryos were divided into 7 age groups, from l3 to 50 days. The doses of x rays ranged from 27 to 400 r. Each pregnant female was anesthetized with sodium pentobarbital and a laparotomy was performed. The embryos in one uterine horn were irradiated once. The embryos in the opposite uterine horn served as non-irradiated controls. After irradiation, all embryos were sacrificed and the hematopoietic tissues (yolk sac, liver, spleen, thymus, bone marrow, and lymph gland) were studied. A comparison was made between the tissues of the irradiated embryos, non-irradiated control embryos, and unoperatedcontrol embryos. Hematopoiesis in the yolk sac of irradiated embryos did not differ from that in the control embryos regardless of the age at the time of irradiation. Also, differences in hematopoiesis in the liver, spleen, and thymus were not found between control embryos and 13-day embryos irradiated with 27, 52, or 78 r, or 15-day embryos irradiated with 50 r, or 16-day embryos irradiated with 100 r. Mild to severe fibrosis of the spleen was found in young animals irradiated with 250 or 300 r as 27-day em bryos, and sacrificed at 11, 27, and 28 months after irradiation. The lymphocytes of the thymus were the most sensitive hematopoietic cells studied. The amount of necrosis varied with the age, the number of lymphocytes, and the dose. The lymphocytes showed severe karyorrhexis soon after irradiation, but repopulation was complete within 5 days. This repopulation was followed by hemorrhage, liquefaction necrosis, and degeneration by 7 to 10 days after irradiation. The response of blood cell precursors in the liver was generally the same as in the spleen. After irradiation, the hematopoietic cells in these organs, with exception of megakaryocytes, showed moderate karyorrhexis. Focal erythropoiesis then developed within 2 to 5 days. Myelocytes and megakaryocytes generally disappeared within 5 days after irradiation. The lymphocytes in the spleen disappeared following irradiation and then regenerated, but their concentration never equaled that in the control spleen. In the bone marrow, the hematopoietic cells, with the exception of megakaryocytes, showed severe karyorrhexis after irradiation. Cellular regeneration was generally poor and consisted mostly of erythroblasts. Megakaryocytes never regenerated, and only a few myelocytes were present during the latter part of the 10 day post-radiation period. The lymphocytes in the lymph glands showed only a slight amount of karyorrhexis after the administration of x rays. Regeneration of these cells was better in fully developed lymph glands than in newly formed lymph glands. The mesenchymal cells of all hematopoietic tissues were more radioresistant than were the blood cell precursors. However, an indirect effect was shown in that the progeny of these mesenchymal cells had little or no ability to give rise to more mature cells. In most respects, the effect of irradiation on the embryonic hematopoietic tissues and cells was similar to that described in post-natal hematopoietic tissues and cells.
- Research Organization:
- Univ. of Colorado, Boulder
- NSA Number:
- NSA-16-026790
- OSTI ID:
- 4809342
- Journal Information:
- Dissertation Abstr., Vol. Vol: 22; Other Information: Orig. Receipt Date: 31-DEC-62
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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