scholarly journals Vitamin A Prevents Inner Ear Defects in Mice with Congenital Homeobox Gene Deficiency

2001 ◽  
Vol 1 ◽  
pp. 916-918 ◽  
Author(s):  
Massimo Pasqualetti ◽  
Filippo M. Rijli
Keyword(s):  
Vitamin A ◽  
Inner Ear ◽  
Homeobox Gene ◽  
Gene Deficiency

Nkx5-1 controls semicircular canal formation in the mouse inner ear

Development ◽  
1998 ◽  
Vol 125 (1) ◽  
pp. 33-39 ◽  
Author(s):  
T. Hadrys ◽  
T. Braun ◽  
S. Rinkwitz-Brandt ◽  
H.H. Arnold ◽  
E. Bober
Keyword(s):  
Homologous Recombination ◽  
Inner Ear ◽  
Homeobox Gene ◽  
Semicircular Canals ◽  
Otic Vesicle ◽  
Null Mutation ◽  
Complex Structures ◽  
Vestibular Organ ◽  
Inner Ear Development ◽  
Vestibular Organs

The inner ear develops from the otic vesicle, a one-cell-thick epithelium, which eventually transforms into highly complex structures including the sensory organs for balance (vestibulum) and hearing (cochlea). Several mouse inner ear mutations with hearing and balance defects have been described but for most the underlying genes have not been identified, for example, the genes controlling the development of the vestibular organs. Here, we report the inactivation of the homeobox gene, Nkx5-1, by homologous recombination in mice. This gene is expressed in vestibular structures throughout inner ear development. Mice carrying the Nkx5-1 null mutation exhibit behavioural abnormalities that resemble the typical hyperactivity and circling movements of the shaker/waltzer type mutants. The balance defect correlates with severe malformations of the vestibular organ in Nkx5-1(−/−) mutants, which fail to develop the semicircular canals. Nkx5-1 is the first ear-specific molecule identified to play a crucial role in the formation of the mammalian vestibular system.

Experimental Studies on the Role of Vitamin a in the Inner Ear

1978 ◽  
Vol 86 (4_suppl) ◽  
pp. ORL-595-ORL-620 ◽  
Author(s):  
Richard A. Chole
Keyword(s):  
Vitamin A ◽  
Guinea Pig ◽  
Inner Ear ◽  
Spectral Characteristics ◽  
Experimental Studies ◽  
Normal Function ◽  
Fluorescent Compound ◽  
Guinea Pig Cochlea ◽  
Vitamin A Acid

With the sole exception of the hair cells of the inner ear, where information is lacking, all special somatic afferent receptor cells have been shown to be dependent upon vitamin A for normal function. In view of the paucity of information on the role of vitamin A in the inner ear, three experiments were performed to examine this relationship. Temporal bone histopathology was studied in rats deprived of vitamin A. In a second experiment, vitamin A-deficient rats were maintained with vitamin A acid and the histopathology was studied under the light microscope. In the third experiment, a microfluorometric estimate of the content of vitamin A in the guinea pig cochlea was performed. A fluorescent compound with the exact spectral characteristics of vitamin A was found in the guinea pig cochlea at a concentration of 21.2μg/gm, which is ten times the vitamin A concentration found in most other tissues.

scholarly journals Distinct roles for hindbrain and paraxial mesoderm in the induction and patterning of the inner ear revealed by a study of vitamin-A-deficient quail

2005 ◽  
Vol 285 (1) ◽  
pp. 252-271 ◽  
Author(s):  
Sung-Hee Kil ◽  
Andrea Streit ◽  
Stephen T. Brown ◽  
Nidhi Agrawal ◽  
Andres Collazo ◽  
...  
Keyword(s):  
Vitamin A ◽  
Inner Ear ◽  
Paraxial Mesoderm

Inner ear and maternal reproductive defects in mice lacking the Hmx3 homeobox gene

Development ◽  
1998 ◽  
Vol 125 (4) ◽  
pp. 621-634 ◽  
Author(s):  
W. Wang ◽  
T. Van De Water ◽  
T. Lufkin
Keyword(s):  
Inner Ear ◽  
Homeobox Gene ◽  
Preimplantation Embryos ◽  
Sensory Cells ◽  
Wild Type ◽  
Targeted Disruption ◽  
Horizontal Semicircular Canal ◽  
Hierarchical Relationship ◽  
Inner Ear Development ◽  
Post Implantation

The Hmx homeobox gene family is of ancient origin, being present in species as diverse as Drosophila, sea urchin and mammals. The three members of the murine Hmx family, designated Hmx1, Hmx2 and Hmx3, are expressed in tissues that suggest a common functional role in sensory organ development and pregnancy. Hmx3 is one of the earliest markers for vestibular inner ear development during embryogenesis, and is also upregulated in the myometrium of the uterus during pregnancy. Targeted disruption of the Hmx3 gene results in mice with abnormal circling behavior and severe vestibular defects owing to a depletion of sensory cells in the saccule and utricle, and a complete loss of the horizontal semicircular canal crista, as well as a fusion of the utricle and saccule endolymphatic spaces into a common utriculosaccular cavity. Both the sensory and secretory epithelium of the cochlear duct appear normal in the Hmx3 null animals. The majority of Hmx3 null females have a reproductive defect. Hmx3 null females can be fertilized and their embryos undergo normal preimplantation development, but the embryos fail to implant successfully in the Hmx3 null uterus and subsequently die. Transfer of preimplantation embryos from mutant Hmx3 uterine horns to wild-type pseudopregnant females results in successful pregnancy, indicating a failure of the Hmx3 null uterus to support normal post-implantation pregnancy. Molecular analysis revealed the perturbation of Hmx, Wnt and LIF gene expression in the Hmx3 null uterus. Interestingly, expression of both Hmx1 and Hmx2 is downregulated in the Hmx3 null uterus, suggesting a hierarchical relationship among the three Hmx genes during pregnancy.

Hmx2 homeobox gene control of murine vestibular morphogenesis

Development ◽  
2001 ◽  
Vol 128 (24) ◽  
pp. 5017-5029 ◽  
Author(s):  
Weidong Wang ◽  
Edwin K. Chan ◽  
Shira Baron ◽  
Thomas Van De Water ◽  
Thomas Lufkin
Keyword(s):  
Inner Ear ◽  
Cell Fate ◽  
Critical Role ◽  
Homeobox Gene ◽  
Significant Loss ◽  
Targeted Disruption ◽  
Surface Ectoderm ◽  
Dorsal Portion ◽  
Temporal And Spatial ◽  
Semicircular Ducts

Development of the vertebrate inner ear is characterized by a series of genetically programmed events involving induction of surface ectoderm, preliminary morphogenesis, specification and commitment of sensory, nonsensory and neuronal cells, as well as outgrowth and restructuring of the otocyst to form a complex labyrinth. Hmx2, a member of the Hmx homeobox gene family, is coexpressed with Hmx3 in the dorsolateral otic epithelium. Targeted disruption of Hmx2 in mice demonstrates the temporal and spatial involvement of Hmx2 in the embryonic transition of the dorsal portion (pars superior) of the otocyst to a fully developed vestibular system. In Hmx2 null embryos, a perturbation in cell fate determination in the lateral aspect of the otic epithelium results in reduced cell proliferation in epithelial cells, which includes the vestibular sensory patches and semicircular duct fusion plates, as well as in the adjacent mesenchyme. Consequently, enlargement and morphogenesis of the pars superior of the otocyst to form a complex labyrinth of cavities and ducts is blocked, as indicated by the lack of any distinguishable semicircular ducts, persistence of the primordial vestibular diverticula, significant loss in the three cristae and the macula utriculus, and a fused utriculosaccular chamber. The developmental regulators Bmp4, Dlx5 and Pax2 all play a critical role in inner ear ontogeny, and the expression of each of these genes is affected in the Hmx2 null otocyst suggesting a complex regulatory role for Hmx2 in this genetic cascade. Both Hmx2 and Hmx3 transcripts are coexpressed in the developing central nervous system including the neural tube and hypothalamus. A lack of defects in the CNS, coupled with the fact that not all of the Hmx2-positive regions in developing inner ear are impaired in the Hmx2 null mice, suggest that Hmx2 and Hmx3 have both unique and overlapping functions during embryogenesis.

The homeobox gene Emx2 underlies middle ear and inner ear defects in the deaf mouse mutant pardon

2003 ◽  
Vol 32 (9) ◽  
pp. 1143-1154 ◽  
Author(s):  
Charlotte R. Rhodes ◽  
Nicholas Parkinson ◽  
Hsun Tsai ◽  
Debra Brooker ◽  
Siobhan Mansell ◽  
...  
Keyword(s):  
Inner Ear ◽  
Middle Ear ◽  
Homeobox Gene ◽  
Mouse Mutant

The Morphology of Vacuolated Cells in the Liver Following Administration of Vitamin A.

1973 ◽  
Vol 31 ◽  
pp. 408-409
Author(s):  
Odell T. Minick ◽  
Hidejiro Yokoo ◽  
Fawzia Batti
Keyword(s):  
Electron Microscopy ◽  
Body Weight ◽  
Vitamin A ◽  
Light And Electron Microscopy ◽  
Liver Cells ◽  
Prominent Feature ◽  
Vascular Space ◽  
Vacuolated Cell ◽  
Vacuolated Cells ◽  
Vacuolated Cytoplasm

Vacuolated cells in the liver of young rats were studied by light and electron microscopy following the administration of vitamin A (200 units per gram of body weight). Their characteristics were compared with similar cells found in untreated animals.In rats given vitamin A, cells with vacuolated cytoplasm were a prominent feature. These cells were found mostly in a perisinusoidal location, although some appeared to be in between liver cells (Fig. 1). Electron microscopy confirmed their location in Disse's space adjacent to the sinusoid and in recesses between liver cells. Some appeared to be bordering the lumen of the sinusoid, but careful observation usually revealed a tenuous endothelial process separating the vacuolated cell from the vascular space. In appropriate sections, fenestrations in the thin endothelial processes were noted (Fig. 2, arrow).

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