Fresh visceral examination of rat and rabbit fetuses used in teratogenicity testing.

A method for examining the viscera of rat and rabbit fetuses is described. Techniques used in detecting visceral alterations in rats and rabbits for routine teratogenicity screens have varied over the years. The method used should be quick and simple but at the same time must be accurate, reliable, and comprehensive. The procedure used in this lab is a complete and systematic necropsy of the fresh fetus requiring minimum equipment and time. The examination can be done immediately following cesarean section and yields an intact skeleton which can subsequently be processed for skeletal examination. The fresh specimen and the natural coloration of in situ organs makes color photography of visceral alterations clear and concise. Any lesion can be appropriately fixed for histopathic examination. This technique begins with the examination of the organs in the abdominal cavity and proceeds to the thorax. Of special interest is the procedure used to inspect the internal anatomy of the fresh fetal heart. A description of the internal examination of both rat and rabbit heads and eyes is also included.

Postnatal behavioral effects of ochratoxin A in offspring of treated mice.

Ochratoxin A is a toxic isocoumarin derivative produced by Aspergillus ochraceus and several Penicillium species, which are storage fungi. Many kinds of agricultural commodities can be contaminated with ochratoxin A, which has been reported in both animal and human foods. Pure crystalline ochratoxin A was dissolved in 0.1 N sodium bicarbonate solution and given intraperitoneally to pregnant ICR-derived mice at dose levels of 1.25 and 2.25 mg/kg on gestation days 15, 16, and 17 (day 0, day of insemination). Dams were allowed to deliver, and their litters were culled to eight pups. Dams postnatal development, selected pups were tested for surface righting (days 3-12), swimming (even days 6-20) and pivoting (days 7, 9, and 11). Statistically significant differences for all three tests indicated that a developmental delay had occurred. Brains from the tested offspring were examined by light microscopy; no treatment or dose-related pathoanatomic alterations were found.

Influence of intrauterine position on fetal weight in Dutch belted rabbits.

The influence of intrauterine position on fetal body weight was statistically evaluated for 199 Dutch belted rabbit litters from does receiving various treatments during teratological studies. The data consisted of the number, type (live, dead, resorbed), and position of implantation sites in the left and right uterine horns. Body weights of live fetuses were also recorded. No statistically significant relation was found between the number of live, dead, or resorbed fetuses and intrauterine position. An effect related to differences in position between the left and right uterine horns for the proportions of largest fetuses was statistically significant. This uterine horn effect was not seen for the proportions of smallest fetuses. Positional differences within the uterine horns were significant and indicated a decrease in the proportion of largest fetuses and an increase in the proportion of smallest fetuses with increasing position number (ovarian to cervical end). Mean fetal weights differed significantly between the two uterine horns and among positions. There was a monotonic decrease in fetal weight with increasing position number. There were no significant associations between uterine horn or position and mean weight for the largest fetuses, but statistical evidence of the position effect was seen for weights of the smallest fetuses.