[Ontogenic development of the incudostapedial joint]. / Desarrollo ontogénico de la articulación incudoestapedial.

OBJECTIVE: To study the development of the incudostapedial joint in human embryos and foetuses. MATERIAL AND METHOD: 46 temporal bones with specimens between 9 mm and newborns were studied. The preparations were sliced serially and dyed using the Martins trichrome technique. RESULTS: The incudostapedial joint takes on the characteristics of a spheroidal joint at 16 weeks of development. The cartilage covering the articular surfaces is formed by different strata that develop in succession: the superficial stratum at 19 weeks, the transitional between 20 and 23 weeks, and the radial from 24 weeks on. The subchondral bone develops after 29 weeks by the mechanisms of apposition and extension of the periosteal and endosteal bones, but it is not until week 34 that it completely covers the articular surfaces, following constitution of the bone fascicles transmitting the lines of force. The articular capsule is formed from the inter-zone, the surface zone develops the capsular ligament, and the internal surface develops the synovial membrane. CONCLUSIONS: At the time of birth, the incudostapedial joint is completely developed.

Maintenance of regional histodifferentiation patterns and a spatially restricted expression of type X collagen in rat Meckel's cartilage explants in vitro.

The major, central portion of Meckel's cartilage undergoes fibrous transformation and contributes to the sphenomandibular ligament, whereas its distal end undergoes endochondral ossification ultimately giving rise to inner-ear ossicles. This regional histodifferentiation of Meckel's cartilage is known to be associated with the spatially restricted expression of type X collagen. The objective of this study was to determine if this unique histodifferentiation is regulated by local environmental factors or by a preprogrammed genetic mechanism. Meckel's cartilage, and condylar cartilage used for comparison, were isolated from 17-day-old rat embryos and from newborn rats, respectively. The cartilage explants were maintained in vitro for 50 days with or without supplementation with 10% fetal bovine serum. When the explants were cultured under serum-free conditions, well-regulated cartilage development was observed. Expression of type X collagen, a differentiation marker for hypertrophic cartilage, was restricted to the distal end of Meckel's cartilage, whereas type II and IX collagens were found uniformly along the entire explant. Matrix calcification was examined histochemically using alizarin red S staining and found to be restricted to the distal end of Meckel's cartilage. Both Meckel's and condylar cartilage cultured with 10% fetal bovine serum developed unregulated dysmorphogenesis. These data suggest that, although Meckel's cartilage has an intrinsic potential to differentiate to its terminal stage, external regulatory factors can significantly influence its normal development at the molecular level.

[Some structural characteristics of articulation of the incus and stapes in man]. / Nekotorye osobennosti stroeniia nakovalnestremennogo sochleneniia cheloveka.

Structural characteristics of human incudostapedial articulation (ISA) have been studied on a series of histological sections from temporal bone decalcified pyramids in three planes and by means of macro-micropreparation of tympanal structural elements from 96 human fetuses at various terms of gestation. It was established that the surface of the lenticular process has a spherical form. Its length surpasses its width. The articular surface on the head of the stapes presents a dome-shaped lacuna. The capsule is usually thicker in its posterior part than in the anterior one. It can endure deviation of the long lenticular process up to 3 mm without rupture. When the deviation overruns 3.5 mm, the articular bursa and round ligament of the base of the stapes break. This property of the capsule should be kept in mind when operating on the stapes.

[The autogenous autoclaved incus]. / Der autogene autoklavierte Amboss.

Reimplantation of autogenous ossicles in cholesteatoma involves a fairly high incidence of residual cholesteatoma. The reconstruction of the ossicular chain with alloplastic and allogenic ossicles produces problems such as resorption and extrusion. The autogenous autoclaved ossicle may lead to a new method of reconstructing the ossicular chain in chronic otitis media and cholesteatoma.

[The histological changes in cartilage (incus) in the middle ear after conservation--an animal study (author's transl)]. / Uber das histologische Verhalten von Knorpel (Ambossgelenkpfanne) im Mittelohrraum nach unterschiedlicher Konservierung. Eine tierexperimentelle Studie.

This study demonstrates the histological changes of incus cartilage after transplantation into the middle ear space of rabbits. Conservation was performed by deep-freezing, lyophilisation in connection with gamma-irradiation, or with Cialit in differing dilutions. Controlled deep-freezing at about -196 degrees C and uncontrolled deep-freezing at about -20 degrees C guarantee after transplantion the survival of some vital chondrocytes. The other methods of conservation cause death of all chondroxytes. Cartilage prepared by these methods demonstrates potential for new bone formation. Only the xenogenetic cartilage loses its osteogenic potential after treatment by lyophilisation in connection with gamma-irradiation. The histological value of the transplant differs according to the method of conservation. No special tendency for resorption or inflamatory reactions could be seen.

[Incus homograft--histological study of implanted ossicles (author's transl)]. / Die Homoiotransplantation des Ambosses Histologische Untersuchungen der implantierten Knöchelchen

The methodes of obtaining, preparing and storing of ossicles for homoiotransplantation is described. Using this method, 21 patients have been operated. Four reoperations have been performed, and in two cases implants were found and subsequently subjected to histological analysis. The method of preparing the histological slides is described. The study of examined homografts revealed the normal bone structure and signs of revitalisation, which is clearly shown in the micrographs. On the basis of functional results and histological examination, the authors conclude that the use of devitalised homografts is recommanded in total and/or partial defects of ossicles.

[Histological study of otological homografts (incus, cartilage and fascia) (author's transl)]. / Histomorphologische Untersuchungen an otologischen Homoio-Transplantaten (Amboss, Knorpel und Fascie)

To summarise our morphological findings of this study the following conclusions are drawn: In bone grafts growth of vital cells originating from the Haversian canals is clearly demonstrated. The growth of connective tissue in the Haversian system is understandable on general principles of pathology. The morphology of the change of osteocytes from fibrocytes through osteoblasts is photographically clearly shown and is in keeping with the findings of Steinbach and of Kerr and Smyth. New bone formation was detected at earliest nine months after implantation. Our investigations do not confirm whether this new bone formation occurs persistently in all cases or to what extent the original homograft material, preserves in cialit solution, takes part in this process. A similar mechanism of tissue regrowth should be accepted in homograft cartilage. We have studied two cases, one after 6 months and the other after 5 years following implant. The three fascial grafts examined compare with earlier publications, with oedema, slight inflammation and little shrinkage occurring. The suitability for grafting of homograft incus, cartilage and fascia we believe to have been demonstrated.

The effects of preservation methods on homologous incus transplants in cats.

Experimental incus transplants were performed in cats. The gross findings and histologic data were recorded and correlated to the use of four preservation methods for homografts (alcohol, Cialit, formalin, and freezing). The formalin preserved incudes produced the least middle ear reaction and ossicular fixation. These incudes also exhibited a uniform perivascular bone remodeling throughout the homograft while the bones preserved in Cialit and alcohol were replaced much faster and ossicular chain fixation occurred. The incus bones preserved by freezing were better tolerated than the Cialit and alcohol ones but not as well as the formalin ones.