Pathogenesis of dysplasias of the face and the ear and dystopias of the temporal region.

Dysplasias of the face and ear are supposed to be caused by a premature involution of 3 different embryonal arteries of the branchial arches: (1) Dysfunction of the mandibular artery causes the otocephalia syndrome; (2) that of the stapedial artery causes dysplasias of the face; (3) dysfunction of the hyoid artery entails dysplasias of the ear; and (4) combination of (2) and (3) (dysfunction of truncus hyostapedialis) results in simultaneous dysplasias of the face and the ear. The earlier the deficiency of blood supply occurs the more serious the resulting dysplasias are. The dystopias in the temporal region (auricles, facial nerve, ossicles, petrous bone) are the consequence of an overbending of the proximal hyoid arch caused by a retardation in the development (shortening) of the mandibular arch. Therefore, dystopias of the ear always occur together with dysplasias of the face. Phenotype and appearance on radiographs are discussed.

The intratemporal course of the facial nerve and its influence on the development of the ossicular chain.

Analysis of the information obtained from more than 110 malformations of the external and middle ear operated upon by the author (Gerhardt) leads to speculation as to their course of development. Of particular interest are the varying types of stapes malformations and the influence of variations in the course of the facial nerve on the development and shaping of the stapes. In the light of clinical examples, an attempt was made to interpret the variations in the course of the facial nerve and certain forms of stapes and incus malformation on the basis of the developmental processes in the area of the skull base and of the brain.

[An error in the Reichert-Gaupp theory. A contribution to onto- and phylogenesis of the temporomandibular joint and ear ossicles in mammals]. / Der Irrtum der Reichert-Gauppschen Theorie. Ein Beitrag zur Onto- und Phylogenese des Kiefergelenks und der Gehörknöchelchen der Säugetiere.

The theory of Reichert- Gaupp is refuted by A) new embryological, B) some teratological and C) a new morphological and functional interpretation of palaeontological findings: A) Before the formation of the chondrocranium the still fibrous anlagen of the Meckel's cartilage and of the hyoidal (!) malleus-incus-complex are still sharply outlined each against other. The hyomandibular boundary between them is yet distinctly visible. B) In the malformations being reconducted to an arrest of development the malleus-incus-complex regularly shares the fate of the outer ear (II. visceral arch) but never the destiny of the face (I. visceral arch). The ossicle-chain is not only a functional but also an ontogenetic unit and consequently also a phylogenetic unit. C) The phylogenetic changes of the temporomandibulary joint (tmj) of the Therapsida result by steps out of autochthon (!) structures. The functional background is discussed. We see the articulare as homologue to the processus condylaris and the quadratum to the articular disk. The phylogenetic older quadrato -articular hinge-joint is preserved in the inferior part and the phylogenetic younger quadrato - squamosal slide-joint, which in the human embryo also develops 2 weeks later than the first, is situated superior to the ginglymus . Thus the Mammals have 2 tmj on each side but no squamoso -dental joint.

[Rostral curvature of the proximal visceral segment--a previously unknown embryonal movement]. / Die Rostralkrümmung der proximalen Viszeralbogenabschnitte--eine bisher unbekannte Embryonalbewegung.

Before the development of the chondrocranium within the head region of the human embryo the following different, so far unknown, tissue shifts are demonstrable: Because of the dorsal brain- sheats of the rostral regions of the brain (mes- and diencephalon) don't have yet blood-vessels (area avasculosa ), they are unable to increase and have to be completed by material from more caudal regions. Therefore from the middle of the 5th up to the end of the 7th week of the embryonic life the mesenchymal and ectodermal rhombencephalic brain- sheats are drawn from caudal to rostral. This becomes possible because the rhombencephalon by that passively is put into the pontine and the neck flexures, which also shift rostralwards , thus allowing the hindbrain to shorten. The proximal ends of the visceral arches I and II, where the anlagen of the temporomandibular joint and of the ear are localized, are parts of the latero-basal rhombencephalic brain- sheats . They take part in of this rostral shift. By that all their axial structures, the first branchial groove and the anlage of the auricle synchronistically undergo positional changes proving the rostral bend of the proximal region of the two visceral arches.

[Pathogenesis of the preauricular appendages, melotia, and poliotia (author's transl)]. / Pathogenese der Aurikularanhänge, Melotie und Polyotie.

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.

[A new concept of the normal and pathological development of the primary palate. 1. The normal fate of Hochstetter's epithelial wall]. / Ein neues Konzept zur normalen und pathologischen Entwicklung des primären Gaumens. Teil 1. Das normale Schicksal der Hochstetterschen Epithelmauer.

The following conclusions as to the normal development of the primary palate were drawn from literary and own embryological studies and from morphological evaluations of congenital malformations in this region: 1. The nasal fin or so-called "Epithelmauer" consists of two epithelial layers. It is build, if the epithelial surfaces from the medial and lateral nasal processes touch each other. It represents a masked form of the oro-nasal groove which is also to be found in embryos of sauropsids. Therefore all mammalian embryos have a physiological cleft lip and jaw, which must be removed in order to create a mesenchymal fusion. 2. In its upper part the nasal fin consists of respiratory epithelium (nasal connecting lamina) and in its lower part it consists of oral epithelium (oral connecting lamina). 3. Many findings in the normal embryo and the results of pathological development argue that the cells of the nasal fin are not destroyed by mesenchyme but they persist. 4. Along the differentiation-line the oral epithelium separates gradually from the respiratory epithelium (remaining on the spot). 5. The oral epithelium is moved towards the palate thus permitting the mesenchymal fusion between the adjacent processes of the face. 6. This shifting oral connecting lamina is integrated into the epithelium of the palate.

[Congenital epidermoid tumors of the temporal bone. 1: Pathogenesis]. / Kongenitale Epidermoide des Schläfenbeins. Teil 1: Pathogenese.

Epidermoids (congenital cholesteatomas) of the mastoid air cells lying behind an intact tympanic membrane are not as rare as previously supposed. We discuss the current hypotheses of their pathogenesis critically, and favour the hypothesis of germ scattering. We summarize some not so well known details of the early stages of development of the normal involution of the first branchial cleft and of the first pharyngeal pouch as well as the subsequent development of the external meatus, the tubotympanic recess and the pneumatized spaces of the temporal bone. On this basis the transfer of ectodermal cells to the entoderm, the subsequent transmission from the embryonal closing membrane to the definite pneumatic spaces of the middle ear, and the variable frequency of recurrence of epidermoids in these diverse spaces are explained.

[Normal and pathologic development of the secondary palate--a new concept]. / Die normale und die pathologische Entwicklung des sekundären Gaumens--eine neue Konzeption.

Wether the secondary palate develops in the normal or pathological manner is determined by the following processes: Within the contact-epithelium of each palate process there is a still invisible differentiation boundary between the potential oral and nasal epithelium. It extends from rostral to pharyngeal. A genetically determined and timed regular separation of nasal and oral epithelium and an initial epithelial shift along these differentiation boundaries allow the well-timed "primary" fusion of mesenchyme. A great oral part of the contact-epithelium in the thick primordia of the human hard palate is removed by fragmentation (and formation of epithelial pearls). This leads additionally to the retarded "secondary" mesenchymal fusion. Depending on the absence or only the retardation of the epithelium separation and shift the results are the open and the covered clefts. All normal and pathological developments can occur along the differentiation boundary in total extension or only partially.

[A new concept of normal and pathologic development of the primary palate. 2. The formal genesis of the open and covered cleft lip and jaw]. / Ein neues Konzept zur normalen und pathologischen Entwicklung des primären Gaumens. Teil 2: Die formale Genese der offenen und der gedeckten Lippen-Kiefer-Spalten.

In part 1 of this work we have shown that in each mammalian embryo the nasal fin represents a masked physiological cleft lip and jaw. In this double-layered "Epithelmauer" the process of epithelium separation along the differentiation-line may undergo various fates: 1. It can completely fail to take place (resulting in total cleft lip and jaw) or can be interrupted (resulting in incomplete cleft). 2. The persisting oral epithelium of the nasal fin may be loosened and moved away with a little temporal retardation. Thereby the potential osteoblasts and myoblasts cannot meet and join at right time and they retract away from the midline epithelial seam. The minimal and subcutaneous cleft lip and the submucous clefts of the jaw and the mesenchymal bridges may result. 3. Only in very rare cases the cleft lip and jaw develop in another way, namely if the underdeveloped facial processes do not meet.