[Pathogenesis of the preauricular appendages, melotia, and poliotia (author's transl)].

Preauricular appendages are usually considered deriving from excessively growing or supernumerary auricular hillocks at the border of the first cleft. However, the hypothesis being presented here deduces their origin from hyoidal ectodermal cells which differ from their mandibular host-tissue by a specific genetic potency, effecting the formation of extodermal proliferations. The separation of these germs from the hyoidal ectoderm and their fastening to the mandibular ectoderm happen during the closure of the first cleft, when the hyo-mandibular connecting lamina is regressing during the first half of the 6th week of pregnancy. Their transfer away from the hyo-mandibular boundary, which is situated right in front of the auricle, happens during the developmental movement of the mandibular ectoderm of the embryonal face. Thus the preauricular appendages are characterized as a new kind of choristomas: their germs derive from ectodermal cells and also develop in ectodermal tissue. There is also the embryological evidence, that melotia and poliotia are likewise representing extraordinary big preauricular appendages.