CONGENITAL DEFECTS IN GUINEA PIGS - FETAL RESORPTIONS, ABORTIONS, AND MALFORMATIONS FOLLOWING INDUCED HYPERTHERMIA DURING EARLY GESTATION

Hyperthermia was induced in guinea pigs for 1 hour daily on eight, four, or two occasions on days 4–32 of gestation. Maternal core temperature was elevated for about 90 minutes during and after each exposure and the mean maximum elevation was approximately 3.6°C above normal. There was little effect on gestation or fetal development of treatment during days 4–11 of pregnancy. Fetal resorption occurred following exposure on days 11–15 and abortion was common following exposure on days 15–18. Developmental abnormalities were noted in newborn offspring following heat treatment during days 11–32 and were most common after exposure on days 18–25. Microphthalmia and coloboma followed exposure during the earlier part of this period and micrencephaly during days 15–27. Cataract, exomphalos, talipes, abnormalities of bone development, incisor teeth, and digits of the forelimbs, and renal agenesis occurred in various frequencies particularly following exposure on days 18–25. Amyoplasia affecting muscles of the neck, forelimbs, thorax, and abdomen, which was associated with reduced size of the cervical and thoracic spinal cord, followed exposure on days 26–31. The techniques used to induce hyperthermia are described and possible adverse effects of hyperthermia on fetal development are discussed. Copyright © 1969 Wiley‐Liss, Inc., A Wiley Company