The Permeability of the Placenta of the White Rat to a Specific Hemolysin.

Abstract

In view of the controversy upon placental permeability, the following experiments were undertaken to keep the animal under observation for a longer period than has heretofore been done, and to test placental permeability by means of a definite indicator (in this case immune serum hemolysin against guinea pig corpuscles). The white rat was used as it has been shown (Nicholas, 1925, 1 1926 2 ) that this animal is capable of withstanding the shock incident to the necessary surgical procedure without subsequent abortion. Frequent injections could, therefore, be made into the foetus, and its condition followed through frequent observations.

Specific immune serum hemolysins were prepared by the following method: 3 cc. of a 50 per cent suspension of washed guinea pig corpuscles were injected intraperitoneally twice a week for 3 weeks; the animals were not injected during the succeeding 10 days. The second series of injections was begun at the end of this period, twice a week for 3 weeks, consisting of a 60 per cent corpuscle suspension. The percentage of the corpuscle suspension was increased 10 per cent each week. The serum of 12 rats so treated was then pooled, and the titer taken. While the rat is regarded as being a poor animal, from the standpoint of the strength of the reaction obtained, the low titer hemolysin (titer 500) secured had the advantage of being nontoxic to the rat foetuses.

The experiments with the above material are: 1. The injection of immune serum hemolysin into 14 to 19 day old foetuses; 2. The injection of 50 per cent suspension of washed guinea pig corpuscles into foetuses of the same age, and 3. tests to determine the passage through the placenta of materials from mother to foetus.