Articular and internal remodeling in the human otic capsule

Abstract

A comprehensive histologic study of the human otic capsule is presented demonstrating the interrelations between cartilage, bone, blood vessels and soft tissue throughout life. Remodeling occurs through continual degeneration of chondrocytes within the uncalcified articular surfaces of the stapediovestibular joint and through continual degeneration of cartilage about the cochlea and semicircular canals. Degenerated chondrocytes are removed by macrophages and new endochondral bone forms from adjacent osteogenically active blood vessels. The cartilage surfaces of the footplate and oval window are constantly replenished by new cartilage formed by mesenchymal cells of the annular ligament. Within the otic capsule, new cartilage forms from mesenchymal cells lining the labyrinth. Cartilage foci continually undergo partial replacement by endochondral bone with remnants of uncalcified cartilage matrix remaining, forming globuli ossei and interglobular spaces. In addition to continual endochondral bone formation partially replacing the continually forming and degenerating cartilage, chondroid bone forms by direct transformation of some cartilage to bone. These chondroid bone areas are cellular in young age groups, but become pale and relatively acellular with age. These processes occur throughout life, regardless of age or sex.

Inner ear ossification and mineralization kinetics in human embryonic development - microtomographic and histomorphological study

“…4C). Previous works on decalcified specimen described a development of the trabecular bone without thickening of the inner cortex 4 . However, the evolution of techniques allowed us to clearly visualize the maturation of the otic capsule bone, proceeding through a predominant thickening of the external cortex and bone marrow cavity obliteration.…”

“…Different patterns of inner ear developments have been suggested, some advocating a prenatal maturation of the bony labyrinth based on the observation of complete ossification of the surrounding otic capsule by seven months in utero 4 , and others claiming that the temporal bone undergoes further postnatal changes 5 . However, in most previous works, investigations of fetal inner and middle ear ossification in human fetuses were based on histological examination of decalcified temporal bones specimens 6 and/or on three-dimensional (3D) images extrapolated from serial histological slices 7 , which made accurate measurements quite challenging.…”

Developmental Anatomy of the Mouse Stapediovestibular and Temporomandibular Joints

“…But no decrease in the cell population and matricial fibers or proportional changes in the collagen and elaunin fibers were evident in the annular ligament. A study in the literature has reported that remodeling in the cartilage of the SVJ and otic capsule involves absorption by macrophages and replenishment by mesenchymal cells in the annular ligament and lining cells of the labyrinthin (Gussen 1968b). We did not observe massive accumulation of macrophages, fibroclasts or osteoclasts in the vicinity of the annular ligament that would indicate active tissue decomposition in the healthy functional joint containing highly remodeling tissues.…”

Three-dimensional regular arrangement of the annular ligament of the rat stapediovestibular joint

“…The major etiopathogenetic causes of otosclerosis are considered to be genetic factors, collagen defects, collagen autoimmunity and viral infection (Chole and McKenna, 2001). So far, numerous histopathological studies on the SVJ have been performed (Davies, 1948;Harty, 1953;Brunner, 1954;Wolff and Bellucci, 1956;Gussen, 1968Gussen, , 1969Bolz and Lim, 1972;De Souza et al, 1991;Okumura and Iwai-Liao, 1993;Merchant et al, 2001;Whyte et al, 2002). In the normal SVJ, both the vestibular surface and the rim of the stapedial base are covered with hyaline cartilage.…”