Experimental study of the embryology in the ear

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1. Normal development of the ear The normal development of the external and middle ear in the mouse was observed histologically. Especially, main structures in the middle ear were clarified on the embryological stapes. The developmental origin of the stapes footplate was investigated and confirmed to be derived from the otic capsule in the vestibular surface of the footplate. On the external ear, formation of the tympanic membrane was observed at the 10 or 11 days after the birth.2. The experimental studies of teratogenicity of Vitamin A and the inhibitory effect of alkaloid on it.Mother rats were divided into 4 groups consisted of rats treated with Vitamin A, Vitamin A and Cepharanthin ( a kind of alkaloid), Cepharanthin and nothing as control at day 10 of pregnancy. In the results, the frequency of external malformations in fetuses induced by maternal hypervitaminosis A was remarkably decreased in the group treated with Cepharanthin. Further more, the same meterials were stained with … More bone and cartilage staining method and thefindings of their middle ear region were observed. From these studies, the inhibitory effect of Cepharanthin to the teratogenic activity of excessive Vitamin A on the external and internal malformations was suggested concerning with the membrane stabilizing effect of Cepharanthin.3. Embryological observations of the mouse ear using organ culture techniqueThe ear region in the 10th gestation day mouse embryo was explanted into the organ culture system and was cultured for 4 days to 10 days.The tissues of ear region cultured for 4 or 5 days showed the developing sensory epithelium in the inner ear, cartilaginous otic capsule, acoustico-facial ganglion cells, facial nerve fibers and anlage of ossicles in their histological specimens.4. Developmental study of the rat ear using whole embryo culture technique.Rat embryos were explanted at 11.5 days of gestation and cultured for 24 hours using the whole embryo culture technique.Morphological and histological examinations were made on the ear region of the cultured and control embryos. In the control group, otocysts were simple and oval in shape.In the cultured embryos, otocysts elongated and narrowed and endolymphatic ducts could clearly be seen. Less