Contribution to morphological knowledge of the development of the human incudo-mallear joint.

CONCLUSION: At the time of birth, the incudo-mallear joint is completely developed. OBJECTIVE. To study the development of the incudo-mallear joint in human embryos and fetuses. MATERIALS AND METHODS. In all, 46 temporal bones with ages between 9 mm and newborns were studied. The preparations were cut in a series and dyed using Martins' trichrome technique. RESULTS. The incudo-mallear joint acquires the characteristics of a saddle joint at 10 weeks of development. The cartilage that covers the articular surfaces is formed by different strata that develop successively: the superficial stratum at 14 weeks, the transitional between 15 and 19 weeks, and the radial from 20 weeks. The subchondral bone develops between weeks 25 and 28 by the mechanisms of apposition and extension of the periosteal and endosteal bones, but it is not until week 30 that it completely covers the articular surfaces, consisting of bone fascicles whereby the lines of force will be transmitted. The articular capsule is formed as from the inter-zone. The surface zone develops the capsular ligament, and the internal surface develops the synovial membrane. Even though it is not consistent, the primordium of the meniscus is seen at 18 weeks.

[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.

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

Objetivo: Estudiar el desarrollo de la articulación incudoestapedial en embriones y fetos humanos. Material y método: Se han estudiado 46 huesos temporale scon ejemplares comprendidos entre 9 mm y recién nacidos. Las preparaciones estaban cortadas en serie y teñidas con la técnica de tricrómico de Martins. Resultados: La articulación incudoestapedial adquiere las características de una articulación sinovial de tipo enartrosisa las 16 semanas de desarrollo. El cartílago que recubre las superficies articulares está formado por diferentes estratos que se desarrollan sucesivamente: el superficial, a las 19 semanas; el de transición, entre las 20 y las 23 semanas, y el radial, a partir de las 24 semanas. El hueso subcondral se desarrolla a partir de las 29 semanas por los mecanismos de aposición y extensión del periostal y el endostal, pero no es hasta la semana 34 cuando recubre por completo las superficies articulares, constituidos los fascículos óseos por los que se transmitirán las líneas de fuerza. La cápsula articularse forma a partir de la interzona, la zona superficial desarrolla el ligamento capsular y la interna, la sinovial. Conclusiones: En el momento del nacimiento la articulación incudoestapedial está completamente desarrollada (AU)

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 new-borns 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 (AU)

[Connections between bone marrow and mesenchyme of the middle ear]. / Conexiones entre la médula ósea de los osículos y el mesénquima del oído medio.

OBJECTIVE: To investigate the presence of connections between the bone marrow of the ossicles and the mesenchyme that fills the future tympanic cavity. MATERIAL AND METHODS: Ninety temporal bones from embryos and foetuses were examined, selecting 15 aged between 20th to 30th weeks of development, to show connections between ossicle marrow and mesenchyme. RESULTS: The connections are transitory and appear in the malleus and the incus between 20th to 24th weeks of development, while in the stapes appear later, being between 24th to 28th weeks. CONCLUSIONS: These connections may have an important role in the phagocytosis of the mesenchymal remains and join in the detritus elimination mechanisms produced during the regression.

Conexiones entre la médula ósea de los osículos y el mesénquima del oído medio / Connections between bone marrow and mesenchyme of the middle ear

Objetivo: Determinar si existen conexiones entre la médula ósea de los osículos timpánicos y el mesénquima que rellena la futura cavidad timpánica. Material y métodos: Se han examinado 90 huesos temporales pertenecientes a embriones y fetos, y se han seleccionado 15 de edades comprendidas entre las semanas 20 y 30 del desarrollo al presentar conexiones entre médula del osículo y el mesénquima. Resultados: Las conexiones son de tipo transitorio y aparecen en el martillo y el yunque entre las semanas 20 y 24 de desarrollo, mientras que en el estribo se manifiestan posteriormente, entre las semanas 24 y 28. Conclusiones: Estas conexiones pueden tener un papel importante en la fagocitosis de los restos mesenquimales y sumarse a los mecanismos de eliminación de los detritus producidos durante la regresión

Objective: To investigate the presence of connections between the bone marrow of the ossicles and the mesenchyme that fills the future tympanic cavity. Material and methods: Ninety temporal bones from embryos and foetuses were examined, selecting 15 aged between 20th to 30th weeks of development, to show connections between ossicle marrow and mesenchyme. Results: The connections are transitory and appear in the malleus and the incus between 20th to 24th weeks of development, while in the stapes appear later, being between 24th to 28th weeks. Conclusions: These connections may have an important role in the phagocytosis of the mesenchymal remains and join in the detritus elimination mechanisms produced during the regression