[An experimental models in the evaluation of the effect of the amniotic fluid]

Fetal life develops in a fluid environment. Amniotic fluid is not inert. It contains proteins, hormones, fetal urine and electrolytes, known to interact with a variety of fetal processes such as wound healing, intestinal growth, etc. Interest in its study has been increasing recently. In order to determine the effect of amniotic fluid, intra-amniotic and extra-amniotic fetuses should be compared. We describe a model that allows isolation of a fetal portion from amniotic fluid. Sixty 23-day pregnant rabbits were operated on. Surgery was performed in two fetuses of each mother. One fetus was replaced into the amniotic sac; the other was sutured along its waist to the histerotomy orifice, leaving the caudal half of the fetus in an extra-amniotic position. The mothers continued their pregnancy and were sacrificed on day 30. Maternal survivance rate was 82 per 100. Twelve intra-amniotic fetuses (FIA) and nine extra-amniotic fetuses (FEA) were obtained, as well as 16 nonoperated littermates that served as controls. The average weight of FIA fetuses was 31 g, FEA fetuses weighed 37 g and controls 36 g. The difference was not statistically significant between any of the groups. This model allows the study of a variety of fetal conditions in the absence of amniotic fluid. The survivance rate of this technique of extrauterine fixation has been 75 per 100.