Other papers Prenatal Development of Palatal Surface Structures

Buchtová M.: Prenatal Development of Palatal Surface Structures. Acta Vet. Brno 2002, 71: 523-528. The aim of this study was to determine the beginning development of palatal surface. The surface structures were studied by scanning electron microscopy in foetuses and embryos of European pine vole (Microtus subterraneus, Arvicolidae, Rodentia). The estimated age of the subjects ranged from 13 to 21 days (pregnancy period is 21 days). The palatal surface is characterised by ridges (rugae palatinae), the number of which is speciesspecific (in adult European pine voles 7 to 8). For the purpose of this study, the palate was divided into the rugal area (zone of palatal ridges) and the interrugal area (zone between the individual palatal ridges). The formation of surface structures in apical parts of epithelial cells was observed in the late embryonic period at ontogenesis days (OD) 12.5 to 13.5, when the lateral palatal processes were still oriented vertically. The cell surface was characterised by rarely dispersed minute cytoplasmic projections, sometimes arranged into rows along cell borders. In the early foetal period (OD 17 to 18), when the palatal processes were fused, the surface structures formed irregular lines (microplicae) particularly in rugal areas, and numerous short microvilli in the interrugal areas. Later, the individual microvilli merged into lines, which increased and formed a dense tangle of microvilli. Hence, before birth the surface pattern was similar to that seen in adult individuals. The microplication proceeded in adults to the extent that borders of the individual lines became indistinct and the palatal surface attained a pitted appearance. SEM, microplicae, microvilli, rugae palatinae, palate Scanning electron microscopy was used to study epithelial surfaces of various mammalian organs by a number of authors. The respiratory epithelium was studied by Lenz (1973), Greenwood and Holland (1972), and Andrews (1979), the corneal epithelium by Blümcke and Morgenroth (1967) and Goller (1990), and the vaginal epithelium by Parakkal (1974). The studies demonstrated the presence of surface cytoplasmic folds on numerous cells, which were termed cytoplasmic folds (Merr i lees 1974), microvillar ridges (Harr is and Hunt 1975), microridges (Sperry and Warsersug 1976), microrugae (Bánóczy et al. 1980), or microplicae (Blümcke and Morgenroth 1967). The surface structure of the oral epithelium during the prenatal development was studied in various animal species. Waterman et al. (1973) described progressive changes in the palatal fusion area of mice. Peterková et al. (1987) and Sakamoto et al. (1989) concentrated on the development of palatal ridges in mice. Schüpbach et al. (1983) monitored the development of the secondary palate of rat including changes in palatal ridge patterns and the fate of the fusion line on the hard and the soft palates. Meller et al. (1980) described changes in surface topography in pre-fusion stages of the secondary palate development in rabbit embryos, concentrating on changes in surface epithelial cells along the medial edges of palatal processes. ACTA VET. BRNO 2002, 71: 523–528 Address for correspondence: Mgr. Marcela Buchtová Department of Anatomy, Histology and Embryology, Faculty of Veterinary Medicine University of Veterinary and Pharmaceutical Sciences Palackého 1-3, 612 42 Brno, Czech Republic Phone: +420 541 562 214 Fax: +420 541 562 217 E-mail: [email protected] http://www.vfu.cz/acta-vet/actavet.htm