Volume 14, Number 4, December 2002
| | Histopathology of Cleft Lip Muscle: an Enzyme Histochemical and Electron Microscopic Study |
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Champika J Wijayaweera,1 Asoka de S Amaratunga,2 Preethika Angunawela3
1Department of Anatomy, Faculty of Medical Sciences, University of Sri Jayawardenepura, Sri Lanka
2Department of Oral Surgery, Faculty of Dental Sciences, University of Peradeniya, Sri Lanka
3Department of Pathology, Faculty of Medicine, University of Colombo, Sri Lanka
Abstract
Objective: This study was performed to identify the histopathological changes in the cleft lip muscle and its possible relationship to the pathogenesis of clefting.
Patients and Methods: Biopsies of orbicularis oris muscle were obtained from the lateral cleft edge of 40 infants with unilateral complete cleft lip with or without cleft palate. Control samples were obtained from 13 infants who had accidental trauma to the lip. Frozen sections 8 µm thick were cut and stained with haematoxylin and eosin and examined for succinate dehydrogenase, nicotinamide adenine dinucleotide, and adenosine triphosphatase at pH 9.4, 4.2, and 4.6. The rest of the biopsy was used for electron microscopic studies.
Results: There was a reduction in the number of muscle fibres with a relative increase in connective tissue in cleft lip muscle. There was a generalised reduction in the diameter of both type 1 and type 2 fibres and the quantity of type 2 fibres was increased. The cleft muscle showed increased oxidative enzyme activity and centrally located conglomerates of formazan deposits. Electron microscopic studies showed mitochondrial aggregates and morphological alterations. Other ultrastructural features of the cleft lip muscle were comparable with those of the control samples.
Conclusion: These results show that cleft lip muscle is intrinsically different from healthy control muscle. The changes observed in cleft lip muscle are comparable with changes seen in developing muscle that is exposed to hypoxia. The role of hypoxia as a possible pathogenic factor that acts on the developing primary palate region during the critical period of development is discussed.
Key words: Anoxia, Cleft lip, Microscopy, electron
Asian J Oral Maxillofac Surg. 2002;14:219-225.
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