Fetal development and growth of the fissula ante fenestram in the human ear.
José Francisco Rodríguez-VázquezMaría Cruz Iglesias-MorenoAdriana PochGen MurakamiHiroshi AbeYohei HonkuraPublished in: Anatomical record (Hoboken, N.J. : 2007) (2021)
Since the fissula ante fenestram (FAF) is considered as a focus of otosclerotic lesion and a route of perilymph leakage, there are few description of prenatal development of the cartilaginous canal passing though the cochlear wall. We examined the sagittal and frontal histological sections of the ear from 32 human fetuses at 8-37 weeks of gestational age. At 8-12 weeks, in the immediately anterior side of a connection between the cochlear and canalicular parts of the otic capsule cartilage, the FAF appeared as a tear of a cartilage between the basal and second turns of the cochlea. The tear became a slit opening to the scala vestibuli. At 13-15 weeks, the FAF, less than 1.2 mm in length, had the anterosuperior and postero-inferior apertures: the former was near the geniculate ganglion and became closed after 15 weeks, while the latter approached the oval window. Third trimester fetuses, the FAF, 1.5-2.0 mm in length, consistently carried a single, postero-inferior aperture extending along the anterior margin of the oval window and it contained no definite epithelium and vessel. Although it was endochondral ossification, there was no clear zonation in cartilage cells of the FAF. A mechanical stress during three-dimensional coiling of the cochlear ducts seemed to provide the FAF. After the FAF was established, the stapes footplate might use a part of the inferior aperture for the syndesmosis. A specific ossification was seen in the FAF, but it might rarely cause the pathological syndesmosis.
Keyphrases
- gestational age
- birth weight
- preterm birth
- endothelial cells
- extracellular matrix
- pregnant women
- induced apoptosis
- induced pluripotent stem cells
- pluripotent stem cells
- working memory
- signaling pathway
- neuropathic pain
- cell proliferation
- spinal cord
- spinal cord injury
- functional connectivity
- heat stress
- optical coherence tomography
- weight gain
- oxidative stress
- optic nerve