Talk:Hearing - Inner Ear Development

New insight into the bony labyrinth: a microcomputed tomography study. Richard C, Laroche N, Malaval L, Dumollard JM, Martin Ch, Peoch M, Vico L, Prades JM. Auris Nasus Larynx. 2010 Apr;37(2):155-61. Epub 2009 Jul 4. PMID: 19577870 http://www.ncbi.nlm.nih.gov/pubmed/19577870

"Our findings show different rates of growth among the semicircular canals, the vestibular aqueduct, the oval window, the round window and the cochlea. The final sizes of the cochlea and round window are achieved at 23 weeks of gestation, with heights of 5mm and 2mm, respectively. The oval window reaches adult size at 35 weeks, whereas the vestibular aqueduct will attain adult size after birth. An increasing degree of torsion of each semicircular canal is observed during fetal development. The superior semicircular canal achieves adult size at 24 weeks, before the posterior and the lateral canals (25 weeks). The time-course of ossification and mineralization observed in structures and confirmed by histology. CONCLUSIONS: During this developmental period poorly studied until now, our findings suggest that each part of the bony labyrinth follows distinct growth and ossification kinetics trajectories, some of these reaching their adult size only after birth. Copyright (c) 2009 Elsevier Ireland Ltd. All rights reserved."

Development of form and function in the mammalian cochlea. Kelly MC, Chen P. Curr Opin Neurobiol. 2009 Aug;19(4):395-401. Epub 2009 Aug 15. Review. PMID: 19683914 http://www.ncbi.nlm.nih.gov/pubmed/19683914

Masculinization of the mammalian cochlea. McFadden D. Department of Psychology and Center for Perceptual Systems, University of Texas at Austin, Seay Building, 1 University Station, A8000, Austin, TX 78712-0187, USA. mcfadden@psy.utexas.edu Abstract Otoacoustic emissions (OAEs) differ between the sexes in humans, rhesus and marmoset monkeys, and sheep. OAEs also are different in a number of special populations of humans. Those basic findings are reviewed and discussed in the context of possible prenatal-androgen effects on the auditory system. A parsimonious explanation for several outcomes is that prenatal exposure to high levels of androgens can weaken the cochlear amplifiers and thereby weaken otoacoustic emissions (OAEs). Prenatal androgen exposure apparently also can alter auditory evoked potentials (AEPs). Some non-hormonal factors possibly capable of producing sex and group differences are discussed, and some speculations are offered about specific cochlear structures that might differ between the two sexes. PMID: 19272340