Importance of region-specific epithelial rearrangements in mouse rugae development

Abstract

Epithelial appendages on palatal rugae develop during mouse palatogenesis through epithelial thickening and pattern formation. Recently, the patterned formation of nine rugae was observed together with the specific expression patterns of Shh in rodents. However, no crucial evidence was found for a direct association between Shh expression and the distinct structural formation of rugae. In order to reveal possible relationships, we investigated the morphological changes of rugae and expression patterns of Shh directly by in vitro organ culture at embryonic day 13 (E13) for 2 days. To compare and examine the diverse growing aspects of the palate and rugae, we carefully observed the detailed morphogenesis, with cell proliferation of the rugae occurring between E13 and E14.5. After 2 days of cultivation at E13, DiI micro-injections revealed that the middle part of the palate, adjacent to the upper molar-forming region, contributed to the formation of the subsequent structure of rugae by extensive cell rearrangement and proliferation within the epithelium in the preferred anteroposterior direction. The results also defined the intimate relationship between Shh expression and rugae formation.

Factors affecting facial development and formation of cleft lip and palate: a literature review

“…SHH is required for mesenchymal cell survival in early stages of development and for cell proliferation in later stages [19,49]. Before the palatal shelve elevation and fusion, SHH is found in the oral side of the palatal epithelium, aft erwards only in spots of thickened epithelium (rugae) [43,50]. Th e enhanced SHH signalling might have a restrictive role in WNT signalling by enhancing WNT antagonist signalling [51].…”

Role of region-distinctive expression of Rac1 in regulating fibronectin arrangement during palatal shelf elevation

“…The E13.5 embryonic maxillary regions, including palatal shelves, were cultured in suspension by using the roller culture system for 48 h with or without treatment, as previously described (Sohn et al 2011). Briefly, the E13.5 embryonic maxillary regions, including palatal shelves, were dissected by using syringe needles.…”

Rgs19 regulates mouse palatal fusion by modulating cell proliferation and apoptosis in the MEE

“…In vitro organ cultivation methods including roller and Trowell's modified methods were employed to evaluate the developmental roles of Rgs19 in palatal development (Lee et al, 2008;Sohn et al, 2011). The in vitro cultivation systems mimicked the in vivo palatal development.…”

“…Procedures for in vitro organ culture were carried out at E13 for 1 or 2 days as described previously (Sohn et al, 2011). After the removal of brain forming tissues, dissected maxilla region including palatal shelves were cultivated in a 8-ml of BGJb medium containing 1% penicillin-streptomycin for 1 or 2 days in a 50-ml penicillin bottle.…”