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Fine structure of extracellular matrix and basal laminae in two types of abnormal collagen production: L-proline analog-treated otocyst cultures and disproportionate micromelia (Dmm/Dmm) mutants.
- Source :
-
Hearing research [Hear Res] 1997 May; Vol. 107 (1-2), pp. 125-35. - Publication Year :
- 1997
-
Abstract
- L-Azetidine-2-carboxylic acid (LACA), a naturally occurring vegetable imino acid, can be incorporated into mammalian proteins in place of proline, thereby eliciting an inhibitory effect on collagen secretion. Exposure of explants of the embryonic mouse inner ear to LACA reduces the number of collagen fibrils in the otic capsule, gives rise to a dose-dependent derangement of the basal lamina, and ultimately results in dysmorphogenesis and retarded differentiation of the inner ear. Disproportionate micromelia (Dmm) is an incomplete dominant form of dwarfism characterized by a reduced quantity of type II collagen in the cartilaginous extracellular matrix (ECM). Abnormal morphogenesis in homozygotic Dmm mice resembles the abnormal morphogenesis observed in LACA-exposed otic explants, resulting in malformed inner ears with a bulky cartilaginous capsule and a lack or reduction of defined perilymphatic spaces (Van De Water and Galinovic-Schwartz, 1987). In this study, we examined by ultrastructural analysis LACA-exposed otic explants and inner ears of Dmm/Dmm mouse embryos for abnormalities in the collagenous constituents of the basal laminae and capsular ECM. We demonstrate, in comparison to normal embryonic mouse inner ears, a reduction in collagen fibrils and irregular cytodifferentiation of chondrocytes in the ECM of LACA-exposed and Dmm/Dmm inner ears as well as in the basal laminae of LACA-exposed specimens. In addition, we provide evidence of dysmorphogenesis of the otic capsule and perilymphatic spaces in LACA-exposed explants. Moreover, while previous studies demonstrated the anomalous development of sensory structures in otocyst explants following LACA exposure, in this study we provide evidence of the normal morphogenesis of otic epithelial-derived sensory structures in homozygotic Dmm/Dmm mouse embryos.
- Subjects :
- Animals
Basement Membrane ultrastructure
Cartilage abnormalities
Cartilage embryology
Cartilage ultrastructure
Cochlear Aqueduct abnormalities
Cochlear Aqueduct embryology
Cochlear Aqueduct ultrastructure
Ear, Inner embryology
Extracellular Matrix ultrastructure
Female
Heterozygote
Homozygote
Mice
Mice, Inbred C57BL
Mice, Inbred CBA
Mice, Mutant Strains
Microscopy, Electron
Osteochondrodysplasias embryology
Osteochondrodysplasias genetics
Osteochondrodysplasias metabolism
Phenotype
Pregnancy
Azetidinecarboxylic Acid toxicity
Collagen biosynthesis
Ear, Inner drug effects
Ear, Inner metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0378-5955
- Volume :
- 107
- Issue :
- 1-2
- Database :
- MEDLINE
- Journal :
- Hearing research
- Publication Type :
- Academic Journal
- Accession number :
- 9165353
- Full Text :
- https://doi.org/10.1016/s0378-5955(97)00028-2