The early development of palatal rugae in the rat

Abstract

The palatal rugae in rats are contained in two of three zones of morpho-differentiation and develop around the time of palatal closure. Previous studies in humans and pigs have been based on crown-rump lengths but now controlled breeding in rats has allowed exact timing to be established. Twenty-nine female DB IX rats were fertilized and sacrificed in a controlled procedure and foetuses processed for light microscopy and SEM. Serial sagittal sections were made and stained with haematoxylin and eosin and Verhoef's stains. At day 13 the palate was open and no rugae were visible. At day 14 the palatal shelves had started to migrate medially and the ante-molar rugae appeared. At day 15 the palatal shelves were touching and the inter-molar rugae became visible, and at day 16 fusion was all but complete and the definitive rugal pattern established. The development and differentiation is more advanced than in humans and it is concluded that the rugae probably have a role to play in the oral function of animals whereas in humans they are becoming attenuated and the development timetable is retarded because of redundancy.

Establishing identity using cheiloscopy and palatoscopy

“…Their role in human oral function seems to be increasingly less important, which might explain why their development time is retarded [51,54]. Once formed, they do not undergo any changes except in length, due to normal growth [55], remaining in the same position through out an entire person's life [11,20,23,47].…”

Palatal rugae patterns in Australian Aborigines and Caucasians

“…1 T h e development and differentiation of rugae are more advanced in rats than humans and while they are probably involved in oral function in animals, rugae seem to be attenuating in humans. 7 R e s e a r c h e rs have found the task of classification a difficult aspect of studying rugae. Most studies are based on the systems devised by Lysell, 1 and Thomas and Kotze, 2 although they may differ in detail.…”

Morphological study of rugae palatinae in Sudanese Nubians

“…The rugae palatinae are stratified squamous, mainly parakeratinised, epithelium on a connective tissue base that is deeply imbedded between the submucosa fatty tissue and the stratum reticulum of the palatum [24,31]. The structure of the connective tissue of the rugae palatinae is different from the adjacent palatine tissues as its core has delicate reticulin fibres and different numbers and sizes of fibroblasts [28].…”