Preliminary results in this laboratory applying the techniques outlined for the proposed investigation have shown that: 1) primitive otoconia originate from segmentation of an immature otolithic membrane, and 2) that calcium granules (20-150 nm in diameter) first become attached to the external surface of the primitive otoconia and are subsequently incorporated into the organic matrix. The proposed study intends to expand these findings in order to fully investigate the progression of these processes in time and space (age/location). The study intends to characterize the morphological changes that culminate with the differentiation and maturation of chick embryo otoliths by: 1) analyzing the details of the segmentation process of the immature otolithic membrane, 2) analyzing the relationship that exists between the organic matrix and the mineral components, i. e., origin, migration and distribution of the calcium containing granules, and 3) analyzing the differentiation and maturation of the macular epithelia in the vestibular labyrinth. A morphological correlation between the maturation of the otoliths and the macular epithelia, with special emphasis on synaptogenesis at each stage, will be carried out. Twelve different ages between 3-21 days of incubation (stages 15-46) will be examined. Light and electron microscopy histochemistry will be used and serial thick and thin sections of the maculae will be obtained in order to determine the regional changes that probably result in different developmental gradients for each macula. The otoliths provide indispensable cues for sensory perception and physical orientation to the environment. Although abnormality of the vestibular nerve and nuclei contribute to postural imbalance and ataxia, the otolithic end organs provide the primary input for gravitational detection. Without the otoliths vertebrates have great difficulty keeping body balance. Nonetheless, little is known about their development. We must fully understand the normal development of the otoliths before we can begin to understand the changes that genetic deficits and teratogens produce in the embryonic ear.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS022604-03
Application #
3405223
Study Section
Hearing Research Study Section (HAR)
Project Start
1985-09-09
Project End
1988-06-30
Budget Start
1987-09-01
Budget End
1988-06-30
Support Year
3
Fiscal Year
1987
Total Cost
Indirect Cost
Name
Baylor College of Medicine
Department
Type
Schools of Medicine
DUNS #
074615394
City
Houston
State
TX
Country
United States
Zip Code
77030
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Fermin, C D; Martin, D S; Li, Y T et al. (1995) The glycan keratan sulfate in inner ear crystals. Cell Mol Biol (Noisy-le-grand) 41:577-91
Beckman, B S; Mason-Garcia, M; Martinez, M I et al. (1990) Enhanced expression of the beta II subspecies of protein kinase C in differentiating erythroleukemia cells. Exp Cell Res 191:319-22
Fermin, C D; Lovett, A E; Igarashi, M et al. (1990) Immunohistochemistry and histochemistry of the inner ear gelatinous membranes and statoconia of the chick (Gallus domesticus). Acta Anat (Basel) 138:75-83
Fermin, C D; Igarashi, M; Martin, G K et al. (1989) Ultrastructural evidence of repair and neuronal survival after labyrinthectomy in the squirrel monkey. Acta Anat (Basel) 135:62-70
Fermin, C D; Igarashi, M; Yoshihara, T (1987) Ultrastructural changes of statoconia after segmentation of the otolithic membrane. Hear Res 28:23-34
Fermin, C D; Igarashi, M (1987) Morphometry and ultrastructure of the squirrel monkey (Saimiri sciureus) vestibular nerve. Acta Anat (Basel) 129:188-99
Fermin, C D; Igarashi, M (1986) Review of statoconia formation in birds and original research in chicks (Gallus domesticus). Scan Electron Microsc :1649-65
Fermin, C D; Igarashi, M (1985) Morphogenesis and calcification of the statoconia in the chick (Gallus domesticus) embryo: implications for future studies. Physiologist 28:S87-8