Related Experiment Videos
Development of the lip and palate in staged human embryos and early fetuses
1Department of Anatomy, College of Medicine, Pochon Cha University, Kyonggi-Do, Korea.
Insights
Cleft lip and palate are common congenital malformations. This study details lip and palate development in human embryos, providing insights into managing these anomalies.
Area of Science:
- Developmental Biology
- Human Embryology
- Craniofacial Development
Background:
- Cleft lip and palate represent the most frequent congenital malformations in humans.
- Understanding the precise timing of embryonic development is crucial for managing these conditions.
- Existing knowledge on the detailed developmental stages of lip and palate fusion requires further elucidation.
Purpose of the Study:
- To investigate the detailed developmental timeline of human lip and palate formation.
- To establish foundational developmental concepts for the clinical management of cleft lip and palate anomalies.
- To correlate specific embryonic stages with key fusion events in lip and palate development.
Main Methods:
- Examination of 43 staged human embryos and early fetuses (4th to 12th week of gestation).
- Detailed observation and staging of morphological changes during lip and palate development.
- Documentation of the appearance and fusion of key embryonic structures, including mandibular arches, nasal prominences, maxillary processes, palatine processes, and the nasal septum.
Main Results:
- Lower lip fusion completed by Carnegie stage 15; upper lip fusion (medial nasal prominence and maxillary process) completed by stage 20.
- Palatine processes appeared at stages 16-17, with initial fusion with the nasal septum starting at stage 23.
- Complete palatal fusion was observed by the 12th week of development, despite apparent external fusion by the 9th week. The tongue's position relative to palatine processes was noted before stage 23.
Conclusions:
- The study provides a precise timeline for human lip and palate development, highlighting distinct fusion periods.
- These findings are essential for understanding the etiology of various congenital anomalies in the orofacial region.
- The detailed developmental data can inform improved strategies for managing cleft lip and palate.
Abstract:
Cleft lip and palate are the most common congenital malformations in humans. Using 43 staged human embryos and early fetuses ranging from the 4th to 12th week of development, we investigated the development of the lip and palate in order to provide the basic developmental concepts required for managing these anomalies. The lower lip appeared as bilateral mandibular arches at Carnegie stage 11, and these were completely merged at stage 15. The components of the upper lip, medial nasal prominence and maxillary process, appeared at stage 16, and completely merged at stage 20. The median palatine process appeared at stage 16, and the lateral palatine process, at stage 17. The palatine processes and the nasal septum started to fuse abruptly at stage 23, and from external observation seemed to be fused at the 9th week. However, complete fusion did not take place until the 12th week of development. The tongue was prominent at stage 16, showed differentiation of the muscular tissue at stage 21, and was located superior to the lateral palatine process before stage 23. These results may be used in understanding the different mechanisms present in the formation of various congenital anomalies in this region.