Development Genes and Evolution

, Volume 211, Issue 8, pp 388–396

Otx1 null mutant mice show partial segregation of sensory epithelia comparable to lamprey ears

  • Bernd Fritzsch
  • Massimo Signore
  • Antonio Simeone
Original Article

DOI: 10.1007/s004270100166

Cite this article as:
Fritzsch, B., Signore, M. & Simeone, A. Dev Genes Evol (2001) 211: 388. doi:10.1007/s004270100166
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Abstract.

We investigated the development of inner ear innervation in Otx1 null mutants, which lack a horizontal canal, between embryonic day 12 (E12) and postnatal day 7 (P7) with DiI and immunostaining for acetylated tubulin. Comparable to control animals, horizontal crista-like fibers were found to cross over the utricle in Otx1 null mice. In mutants these fibers extend toward an area near the endolymphatic duct, not to a horizontal crista. Most Otx1 null mutants had a small patch of sensory hair cells at this position. Measurement of the area of the utricular macula suggested it to be enlarged in Otx1 null mutants. We suggest that parts of the horizontal canal crista remain incorporated in the utricular sensory epithelium in Otx1 null mutants. Other parts of the horizontal crista appear to be variably segregated to form the isolated patch of hair cells identifiable by the unique fiber trajectory as representing the horizontal canal crista. Comparison with lamprey ear innervation reveals similarities in the pattern of innervation with the dorsal macula, a sensory patch of unknown function. SEM data confirm that all foramina are less constricted in Otx1 null mutants. We propose that Otx1 is not directly involved in sensory hair cell formation of the horizontal canal but affects the segregation of the horizontal canal crista from the utricle. It also affects constriction of the two main foramina in the ear, but not their initial formation. Otx1 is thus causally related to horizontal canal morphogenesis as well as morphogenesis of these foramina.

Ear development Vestibular ganglion Horizontal canal Ear evolution Ear innervation

Copyright information

© Springer-Verlag 2001

Authors and Affiliations

  • Bernd Fritzsch
    • 1
  • Massimo Signore
    • 2
  • Antonio Simeone
    • 2
  1. 1.Department of Biomedical Sciences, Creighton University, Omaha, NE 68178-0405, USA
  2. 2.International Institute of Genetics and Biophysics, CNR, Via G. Marconi 12, 80125 Naples, Italy
  3. 3.MRC Centre for Developmental Neurobiology, New Hunt's House, 4th Floor, King's College London, Guy's Campus, London Bridge, London, SE1 9RT UK