Biomedical subjects

F Declau

Publications and source records attributed to F Declau.

23 records · Page 2Linked to original sources

PubMed1989

Early ossification within the human fetal otic capsule: morphological and microanalytical findings.

Besides the use of conventional techniques such as light and polarization microscopy, the present paper proposes the combined use of transmission electron microscopy, secondary and backscattered electron imaging, energy dispersive X-ray analysis and computed tomography for the diagnostic evaluation of ear pathology in the human fetus. These methods were used to revisit the primary calcification front of the fetal otic capsule between 16 and 23 weeks gestational age. Ultramicroscopic evaluation demonstrates similar fetal bone formation to that found in other bones of the human fetus. The formation of the endosteal and periosteal layers is a typical example of early intra-membranous ossification. The enchondral layer is made up of fibrillar bone, laid down around the calcified cartilage remnants. Microchemical analysis indicates a significantly higher Ca/P ratio in the endochondral layer with respect to the endosteum and periosteum. The consequences of a lower Ca/P ratio in the endosteal layer are discussed in view of calcium homeostasis and inner ear function.

Ear Cartilage↗

PubMed1989

Normal growth pattern of the middle ear cleft in the human fetus.

The normal growth pattern of the middle ear cleft was studied on macro- and histological sections of the human fetus. When compared with adult temporal bones, the inclination of the tympanic ring remains unaltered throughout fetal development. Expansion of the middle ear cleft is caused by intrinsic growth and by lateral displacement of its constituent elements: tympanic ring, otic capsule and squamous bone. Not only are the two mutually different modes of growth movement quite dissimilar in magnitude and direction, but so is their resultant vector for each constituent; this dissimilarity in growth movement leads to a characteristic change in shape of the middle ear cleft and to curvature of the tympanic membrane. The intrinsic growth of these elements is simultaneously accompanied by remodelling of their shape; lateral displacement of the squamous bone and tympanic ring is caused by the pressure of the enlarging brain. The consequences of developmental disturbances on the normal growth pattern are discussed.

Ear, Middle↗

PubMed1988

Differentiation of cartilage and bone in human fetal temporal bones with Luxol fast blue stain.

A modified Luxol fast blue technique was used to study the development of the temporal bone. This staining method makes it possible to make a clear distinction between the primitive cartilage present and the new forming bone. Although these tissues both contain a significant amount of collagen, their staining properties with the Luxol dyes are widely dissimilar, due to the different physicochemical properties of the collagen types involved in these tissues. The differentiation of mesenchymatous tissue into ligaments and joints can also be very clearly demonstrated with this technique. In studying the endochondral ossification process of the otic capsule and middle ear, the modified Luxol fast blue stain is a valuable technique that is complementary to more conventional staining methods.

Cartilage↗

PubMed1988

Congenital middle ear malformations.

After a profound review of normal embryology, a systematical and topographical classification of congenital middle ear malformations in general and of meatal atresia in particular is proposed; the classification of congenital aural atresia is essentially based on the recognition of two types according to the course of the facial nerve in its third segment: in type I, a normal topography of the facial nerve is found and consequently, the middle ear anomalies are rather minimal; in type II, an antero-superior displacement of the facial nerve in its third segment is recognized and the middle ear malformations are considerable worse. In this report, also attention is paid to syndromal nosology and its genetic aspects. In view of functional surgical; reconstruction, the technique of allograft canal surgery, similar to our combined approach tympanoplasty technique, is described in detail and compared with other classical techniques. Preoperative as well as postoperative problems and complications are extensively discussed. The excellent results of our technique are proposed even after 25 years of experience. An overview of cosmetic surgery techniques is given and also alternative techniques with implantable auditory prosthetic materials are summarized.

Deafness↗

PubMed1985

Morphogenesis of the inner ear. Correlation between CT-findings and macrosections.

The development of the temporal bone has been studied on macerated foetuses. For a comprehensive understanding two dissimilar techniques have been linked: CT scan and anatomical dissection technique on frozen tissue. CT scanning has been proved a good method to compare the different stages of maturity. There is also a good correlation between CT images and the anatomical slices obtained by dissection. Both methods are complementary to each other in the study of the morphogenesis of the inner ear.

Adult↗