THE INDIRECT EFFECT OF IRRADIATION ON EMBRYONIC DEVELOPMENT. I. IRRADIATION OF THE MOTHER WHILE SHIELDING THE EMBRYONIC SITE
The experiment described concerns the effect of irradiating a pregnant rat, while shielding the embryonic site on the ninth day of gestation, to determine to what extent the fetus is affected. The dose necessary for fetal malformation when the entire pregnant animal is irradiated is 25 to 100 r; 200 r being 100% lethal to the 9-day rat embryo. Only the external features of the term fetuses were examined, but no congenital malformations were seen, even though the type produced by directly irradiating this stage is quite obvious. In spite of 400 r, whole-body irradiation and 1000 and 1400 r partial-body irradiation on the ninth gestational day, no external teratology was observed in the fetuses. This would indicate that it is apparent that direct irradiation of the embryonic site is responsible for the teratologic effect of x irradiation. It is tempting to speculate that direct irradiation is wholly responsible at all other stages of gestation for teratology. This is probably correct, but the final evidence is not presented here. The fetal mortality was higher in the irradiated groups. The highest fetal mortality occurred in the 1400 r partial- body irradiation group. The radiation illness produced in the mothers, which includes a host of biochemical, physiological, and morphological changes, did affect the organism's ability to hold on to the fetus. Fetal growth was not affected in the low irradiation group, although those mothers which received the highest dose of irradiation did have smaller fetuses. Although the factors affecting maternal weight gain are multiple and impossible to single out, it is interesting that the 400 r group gained weight at the same rate as the controls, in spite of a higher maternal mortality rate and higher fetal mortality rate. The results reinforce the enigma of what factors are responsible for fetal resorption and fetal malformation. Are they quantitative differences of the same metabolic or physiological alterations or qualitatively different factors ? This experiment offers little light on this problem except to add one more debilitating condition in the mother which alters some aspects of fetal growth and resorption while not producing teratology; this, in spite of the presence of a multitude of changes produced in the maternal organism. (auth)
- Research Organization:
- Jefferson Medical Coll., Philadelphia; Walter Reed Army Medical Center, Washington, D.C.
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-15-023303
- OSTI ID:
- 4058348
- Journal Information:
- A.M.A.J. Diseases Children, Journal Name: A.M.A.J. Diseases Children Vol. Vol: 100
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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