NEUROPATHOLOGICAL EFFECTS OF LOW-LEVEL X-IRRADIATION OF THE MAMMALIAN EMBRYO
An exposure of the 1.5 day mouse embryo (at the 1 to 2 cell stage) to as little as 15 r x rays will delay the early cleavages, increase intra-uterine death and resorption, reduce the number of apparently normals at birth, and occasionally cause the severe brain anomaly of exencephalia (brain hernia) indicating morphogenetic damage. When the embryo at 2.5 days (4 to 8 cells) is exposed to the same low level of 15 r x rays there is less severe damage, and exencephalia has never been produced. However, even some of these embryos go to pieces shortly after exposure or at the time of implantation. Cytologically the most common effect on some embryos of 15 r at 1.5 days is fragmentation of the early cleavages, resulting in reduced and a-nucleate blastomeres. Whether such a reduced but nucleated blastomere could give rise to a stunted fetus is mere conjecture. Other effects of 15 r at 1.5 days are swollen or pyknotic nuclei, hyperchromatic nuclei and occasionally the cytoplasm, and sometimes complete separation of constituent cells of the blastula at a later stage. Damaged blastomeres appear to exude a sticky substance which may be denatured cytoplasmic protein. Radiosensitivity of the embryo appears to be greatest immediately after fertilization and becomes progressively less as development proceeds. Until organogenesis is completed, however, embryonic loss may occur through death and resorption as a result of x irradiation and among the others there may be congenital anomalies and stunting which survive delivery. While extrapolation to other mammals is ill-advised, it is certainly suggestive that the radiosensitivity of the very early mammalian embryo may approach that of a genic mutation, and any exposure is too much. (auth)
- Research Organization:
- Columbia Univ., New York
- NSA Number:
- NSA-16-016212
- OSTI ID:
- 4795608
- Journal Information:
- Military Med., Vol. Vol: 126; Other Information: Orig. Receipt Date: 31-DEC-62
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
Similar Records
LOW LEVELS OF X-IRRADIATION AND THE EARLY MAMMALIAN EMBRYO
FRACTIONATED X-IRRADIATION OF THE MAMMALIAN EMBRYO AND CONGENITAL ANOMALIES