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Objective: This study was performed to investigate how the palatine aponeurosis, medial pterygoid process (MPP) of the sphenoid bone, and tensor veli palatini (TVP) muscle form the pulley: muscle-tendon-bone complex., Design: Mice at embryonic day (ED) 14-17 were used as sample in this study. Azan staining was performed to observe the morphology, and immunohistochemical staining of desmin was performed to closely observe the development of the myotendinous junction. To confirm the bone formation process, immunohistochemical staining of type II collagen (col II), tartrate-resistant acid phosphatase (TRAP), and alkaline phosphatase (ALP) staining were performed. Furthermore, to objectively evaluate bone formation, the major axis and width of the MPP were measured, and osteoclasts that appeared in the MPP were counted., Results: At ED 14 and 14.5, ALP showed a reaction throughout the MPP. The col II-positive area expanded until ED 16.5, but it was markedly reduced at ED 17. The TVP initially contacted with the palatine aponeurosis at ED 16.5. The major axis and width of the MPP and the number of TRAP-positive osteoclasts were significantly increased as the TVP and palatine aponeurosis joined., Conclusions: Therefore, in addition to the tissue units: muscle, tendon, and bone, the interaction in organogenesis promotes rapid growth of the pulley: muscle-tendon-bone complex., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The biosynthesis and hydration of glycosaminoglycans (GAG) has been implicated in the generation of palatal shelf-elevating force(s) in mammals, although the nature of the palatal shelf extracellular matrices during cleft palate formation remains poorly understood. This study quantifies the GAG composition in the palatal shelves of Wistar rat fetuses at various periods of palatogenesis where clefts were induced experimentally using 5-fluoro-2-deoxyuridine (FUDR). For both normal and cleft palatal shelves, hyaluronan, heparan sulphate and chondroitin-4-sulphate were detected but not dermatan sulphate or chondroitin-6-sulphate. Throughout the period of cleft development studied, the total amount of GAG was significantly decreased (by approx. 30%) compared with normal development, this decrease being particularly marked at a time equivalent to post-elevation during normal development (approx. 75%). Furthermore, and unlike normal palatogenesis, no significant differences were recorded between the anterior and posterior parts of the palatal shelves during cleft formation. As for normal palatogenesis, however, the percentages of each GAG were not altered at any stage. The findings are consistent with the view that suppression of GAG biosynthesis is related to the development of cleft palate in FUDR-treated rat fetuses and can therefore be interpreted as providing evidence of a role for the mesenchymal glycoconjugates in shelf elevation during normal palatogenesis.

The synthesis and hydration of glycosaminoglycans (GAG) has been implicated in the generation of a palatal shelf-elevating force in mammals. This study quantifies the GAG composition in the palatal shelves of Wistar rat fetuses at various stages of palatogenesis. Hyaluronan, heparin sulphate and chondroitin-4-sulphate were detected but not dermatan sulphate or chondroitin-6-sulphate. The distribution of the GAG differed in the anterior and posterior regions (i.e. the presumptive hard and soft palates) and with the stage of development. At the time of palatal-shelf reorientation, there were no significant differences for either the total amount of GAG or for the percentages of specific GAG types between anterior and posterior regions. Indeed, the most marked differences were detected at the stages of histogenesis after shelf elevation. Nevertheless, the results support the view that hyaluronan is involved in palatal-shelf reorientation, its percentage being initially high and decreasing after shelf elevation. No changes were detected for the other (sulphated) GAG during the time of elevation. The findings point to the need to correlate the events during histogenesis with changes in the ground substance of palatal-shelf mesenchyme and indicate that there are different developmental mechanisms within the presumptive hard and soft palates.