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At least 379 records · Page 21Linked to original sources
PubMed1990

Congenital malformations of the external, middle, and inner ear produced by isotretinoin exposure in mouse embryos.

Isotretinoin (Accutane), a widely used dermatologic drug, produces severe congenital malformations when used during pregnancy. The isotretinoin teratogen syndrome consists of multiple cardiovascular and craniofacial anomalies, most commonly involving the external ear. This study examined the pathogenesis of isotretinoin teratogenicity in a mouse model, using microdissection and histologic examination of fetal mouse ears after treatment with the drug at various stages of embryonic development. In this study, earlier treatment times frequently produced microtia similar to that seen in affected infants, as well as recognizable patterns of temporal bone and ossicular abnormalities; exposure at a later developmental stage resulted in facial tags with less severely affected ears. Possible teratogenic mechanisms of isotretinoin are discussed. Suitability of the mouse model for studying human congenital craniofacial malformations, such as Goldenhar's and Treacher Collins Syndrome, is also explored.

Abnormalities, Drug-Induced↗
PubMedDate not supplied

Inner ear morphology in Down's syndrome.

A comparative study was made on four pairs of temporal bones from patients with Down's syndrome (trisomy 21) and 15 pairs of temporal bones from other infants of the same age range. Spiral reconstructions showed chochlear length to be slightly shorter in temporal bones from patients with Down's syndrome than that in the controls. Based upon these dimensional measurements, a developmental anomaly of the vestibular apparatus was found.

Cochlea↗
PubMed1987

A histopathological study of the inner ear after the administration of hyaluronan into the middle ear of the guinea pig.

Hyaluronan, 19 mg/ml, was administered into the middle ear cavity of guinea pigs. A control group was subjected to a sham operation. Fourteen days after administration the animals were killed and a macroscopic examination of all middle ears was performed. Surface preparations of the organ of Corti were made and examined by light microscopy. Hair cell loss along the length of the sensory epithelium was quantified. No toxic effect of hyaluronan could be detected either in the middle ear or in the sensory cells in the cochlea. Thus hyaluronan is potentially useful for facilitating middle ear surgery.

Animals↗
PubMed1987

An ultrastructural and functional study of the inner ear after administration of hyaluronan into the middle ear of the guinea pig.

A single dose of hyaluronan, 19 mg/ml was administered into the right middle ear cavity of guinea pigs. The auditory function of the right ear was tested by recording the gross neural action potential (N1) before, directly after, and 28 days after the administration of hyaluronan. In a control group the right ear was sham-operated and the gross neural action potential (N1) was recorded twice; on the day of the sham operation and 28 days later. All animals were killed 28 days after the operation. All treated as well as sham-operated ears and every second intact ear were studied by scanning electron microscopy (SEM.) No ear had signs of hearing deterioration. Macroscopically, most of the hyaluronan was eliminated from the middle ear after 28 days. In the histological examination, pathological stereocilia were found in the apical turn of the cochlea in the ears to which hyaluronan was administered, the sham operated and the intact ears.

Animals↗