RADIATION IN PRENATAL DEVELOPMENT 893 



investigators are probably of different types and it is thus not surprising 

 that the critical periods differ. 



C. THE PERIOD OF THE FETUS 



Very few of the more recent investigators have concentrated their 

 attention on irradiation during the period of the fetus. Thus, the bulk 

 of Table 13-7 represents either early (often inadequate) work, or newer 

 experimental series in which the main emphasis lay on the period of 

 organogenesis but which, for one reason or another, were extended to 

 include the first few days of the period of the fetus. It will, therefore, 

 suffice to mention only the few highlights on which evidence seems 

 adequate. 



1. MORTALITY 



Mortality resulting from irradiation of fetal stages has been found to 

 occur mostly in the period between birth and two weeks of age (see 

 also Table 13-7). The mode is probably shortly after birth, but the fre- 

 quency there is considerably less than for equivalent doses used during 

 the period of major organogenesis (Kaven, 1938a, see p. 874; Russell, see 

 Fig. 13-2). Prenatal death has been noted only by a few authors 

 (Kosaka, 1928c; de Nobele and Lams, 1925; Schinz, 1923) for doses in the 

 neighborhood of 1 SED and above, i.e., even higher than those which will 

 cause early postnatal death. In early experiments where absolute doses 

 were not known (Burckhard, Trillmich, Saretzky), exposures equal to 

 those which would give a high degree of prenatal mortality when given 

 earlier in pregnancy were without effect when given during the period of 

 the fetus. 



A kind of acute fatal radiation sickness may occur during the first week 

 or two following birth. Bagg (1922) reports that 7-ray treatment of 

 rats 2 or 3 days before term produces in approximately half the animals of 

 each litter symptoms of anemia, diffuse edema, and meningeal, spinal 

 cord and subcutaneous extravasations, leading to death at about a week 

 of age. Autopsy revealed fatty degeneration of the liver and desquama- 

 tion of the lining of the intestinal mucosa. Job et at. (1935) report 

 postnatal anemia, diarrhea, hemorrhagic exudates in eye and nose, 

 underweight, and abnormal nervousness following X-ray treatment of 

 rat fetuses with more than 1 "skin unit," but no effect from lower doses. 

 (It is not clear whether 1 skin unit = 1 SED.) Lacassagne and Coutard 

 (1923) found that fifty-three of fifty-four rabbits, which had been irradi- 

 ated 2-3 days before birth, died of ' ' purpura roentgenien. ' ' Death occurred 

 always on the tenth day after birth following a relatively invariable syn- 

 drome (hemorrhagic spots in skin and viscera ; extravasations from peri- 

 toneum, pleura, pericardium; edema; torpor; dyspnea; — note resemblance 



