"The animals were observed daily during and after exposure, and weighed twice weekly and on the day of laparotomy....Prior to sacrifice, the females were anesthetized by chloroform inhalation. The uterus was exteriorized through a mid-line incision in the abdominal wall and was weighed. The uterine horns were opened and the fetuses removed. The following observations and enumerations were made.

a. Number of corpora lutea in every ovary.

b. Number of implantation sites in each horn.

c. Number and location of live and dead fetuses.

d. Number and location of late and early resorption.

e. Weight and crown-rump length of all live fetuses.

f. Gross examination of all fetuses for external anomalies and malformations from head to tail, under a long focal-length lens of 2.5 magnification.

About one-half of the fetuses from each litter were preserved in 95% alcohol for subsequent maceration in 1% aqueous KOH, clearing and staining with Alizarin Red and examination to detect skeletal abnormalities. The remaining fetuses were fixed in Bouin's fluid for free-hand razor-blade sectioning (Wilson method) (1) and examination for visceral and neural anomalies under the dissecting microscope. The uterus and ovaries, from mothers in all groups, were examined for gross changes and preserved in Bouin's fluid for possible histopathologic examination. Other tissues and organs were examined grossly and discarded if found normal.

For statistical evaluation of the data, the litter was considered the experimental unit of treatment and observation. The Fisher exact probability test was used to evaluate the incidence of resorptions and abnormalities among the litters. Maternal and fetal body weights and body measurements were treated statistically by by analysis of variance and Least Significant Difference (LSD) test. The number of corpora lutea, implantations and live fetuses per litter were analyzed by the Mann-Whitney U-test. In all cases, the level of significance chosen was p < 0.05."

F1 Charles River-CD Rats