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PubMedDate not supplied

Incorporation of radioactive calcium into otolithic membranes and middle ear ossicles of the gerbil.

45CaCl2 was injected into gerbils in single or multiple doses, and the resulting radioactivity in serum, otoconial CaCO3, bone samples, and selected labyrinthine epithelium was determined by liquid scintillation spectrometry. Incorporation into both utricular and saccular otoconia occurred at the rate of 0.06-0.07 nmole Ca++ per day, corresponding to a fractional rate of uptake of 0.1%. The retention of radioactivity had a half-life of approximately 11 days. The rate of incorporation of calcium for the middle ear ossicles was 5-7 times that for otoconia and was similar to that for otic capsule and skeletal bone. The level of 45Ca++ was higher in the pigmented regions of the utricular membranous wall than in the non-pigmented areas of the utricular and ampullary wall and in the stria vascularis.

Animals↗
PubMed2001

Rotation of middle ear ossicles during cetacean development.

Cetacean middle ears are unique among mammals in that they have an elongated tympanic membrane, a greatly reduced manubrium mallei, and an incudal crus longum that is shorter than the crus breve. Elongation of the tympanic membrane and reduction of the manubrium is thought to be related to an evolutionary rotation of the incus and malleus out of the plane of the tympanic membrane. We examined if rotation also occurs during ontogeny by comparing the middle ears of two species of dolphins (Delphinus delphis, Stenella attenuata) at different stages of development. We observed that: the incus has the body and crural proportions as in terrestrial mammals early in development; the incudomallear complex rotates approximately 90 degrees following ossification; the tympanic membrane is not elongated until relatively late in development. Therefore, some of the unique characteristics of the cetacean middle ear develop as modifications of an initially terrestrial-like morphology.

Animals↗
PubMedDate not supplied

Morphological effects of nanosecond- and femtosecond-pulsed laser ablation on human middle ear ossicles.

We evaluate the feasibility of nanosecond-pulsed and femtosecond-pulsed lasers for otologic surgery. The outcome parameters are cutting precision (in micrometers), ablation rate (in micrometers per second), scanning speed (in millimeters per second), and morphological effects on human middle ear ossicles. We examine single-spot ablations by a nanosecond-pulsed, frequency-tripled Nd:YAG laser (355 nm, beam diameter 10 microm, pulse rate 2 kHz, power 250 mW) on isolated human mallei. A similar system (355 nm, beam diameter 20 microm, pulse rate 10 kHz, power 160-1500 mW) and a femtosecond-pulsed CrLi:SAF-Laser (850 nm, pulse duration 100 fs, pulse energy 40 microJ, beam diameter 36 microm, pulse rate 1 kHz) are coupled to a scanner to perform bone surface ablation over a defined area. In our setups 1 and 2, marginal carbonization is visible in all single-spot ablations of 1-s exposures and longer: With an exposure time of 0.5 s, precise cutting margins without carbonization are observed. Cooling with saline solution result is in no carbonization at 1500 mW and a scan speed of 500 mms. Our third setup shows no carbonization but greater cutting precision, although the ablation volume is lower. Nanosecond- and femtosecond-pulsed laser systems bear the potential to increase cutting precision in otologic surgery.

Cadaver↗
PubMed1992

[Ear ossicle transplants for reconstruction of sound transmission in the middle ear. A histologic long-term study].

In this study 130 ossicular middle ear transplants were studied. 33 remained in the middle ear for 10 years or longer, one for 21 years. The majority of the grafts show 5% to 40% bone new formation. Absence of vital bone or subtotal host bone replacement is exceptional. The amount of bone new formation appears independent the implantation time. 75% of the grafts show no bone resorption. In 15% sound transmitting might be impaired due to resorption. Grafts with a high degree of bone new formation show less resorption. 21% of the ossicles have signs of inflammation. Inflammation boosts bone turnover with resorption on one hand and new for resorption. Cholesteatoma is the main cause of resorption and inflammation. The critical phase for resorption of the graft are the first two to three years after transplantation. No considerable difference was found between autografts and allografts (homografts). Histological and metabolical properties of the ossicles seem to be responsible for the stability of the graft. Ossicular grafts have a good longterm stability which makes them very suitable for reconstruction of the ossicular chain.

Bone Resorption↗