The teratogenic effects in rabbits of doxycycline, dissolved in polyvinylpyrrolidone, injected into the yolk sac.

A technique was developed for injecting agents into the yolk sac of rabbits to study their teratogenic effects. On the 9th day of gestation the rabbits were laparotomized during ether-oxygen narcosis. The test substance was injected into the yolk sacs in one horn of the uterus, and as control the corresponding solvent was injected into the other horn. On the 28th day of gestation the rabbits were killed, resorptions counted, and fetuses examined for malformations. Three series of studies were made: physiological saline; polyvinylpyrrolidone; and doxycycline dissolved in polyvinylpyrrolidone (DIP). The rate of resorptions and malformations significantly increased after injection of Vibravenos. As polyvinylpyrrolidone was not teratogenic it is concluded that the teratogenic effects of DIP were probably caused by doxycycline.