Authors observed the findings of malformed ear induced by maternal hypervitaminosis A using Wistar rats with combined staining to bone and cartilage. On day 9 or 10 of pregnancy, mother rat was injected water miscible vitamin A (200, 000 IU/Kg) intraperitoneally and fetuses were removed on day 21. This staining revealed differences of findings of ear between 2 groups of fetuses, whose mothers were injected vitamin A on day 9 in group A and on day 10 in B. In A, auricle and tympanic bone were absent in all ears and ossicles, Meckel's and Reichert's cartilages were absent or malformed in almost all of them. On the contrary, in B, auricle, tympanic bone and Meckel's cartilage were normal. Two ossicles except malleus and Reichert's cartilage were abnormal in many ears. Besides, phocomelia was found in all fetuses. Authors concluded that the differences of finding between these 2 groups were due to the difference of sensitivity to teratogenic agent in developing organs at that stage and suggested the possibility of the second arch origin of the considerable part of incus.