Apoptotic epithelial cell death: a prerequisite for palatal fusion. An in vivo study in rabbits.
The aim of the present study was to investigate stage-specific changes in medial edge epithelium during in vivo fusion of embryonic palatal shelves in 25 Russian rabbits.


METHODS
The embryos were dissected following Caesarian section at day 18. Palatal shelves of specific developmental steps (approximation, contact, fusion) were examined by light microscopy, immunohistochemistry and transmission electron microscopy.


RESULTS
Light microscopy revealed that the superfical peridermal cells underwent apoptosis prior to contact of the basal epithelial cells. Following contact, an epithelial monolayer was left on each shelf with an intact basement membrane. Apoptosis of the epithelial cells was followed by discontinuity of the basement membrane. Islands of epithelial cells remained.


CONCLUSIONS
This paper presents new data on palatal development in vivo. The results support our theory that apoptotic medial edge epithelial cell death is a precondition for palatal fusion. There were no indications of epithelial mesenchymal transformation or migration.
Holtgrave
Eva Andrea
EA
Department of Orthodontics and Paediatric Dentistry, School of Dental Medicine, Benjamin Franklin Hospital, Berlin, Germany. holtgrave@medizin.fu-berlin.de
Stoltenburg-Didinger
Gisela
G
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001485:Basement Membrane / Q000166:cytology / Q000196:embryology; D002455:Cell Division; D002467:Cell Nucleus / Q000648:ultrastructure; D002863:Chromogenic Compounds; D003593:Cytoplasm / Q000648:ultrastructure; D005314:Embryonic and Fetal Development; D004847:Epithelial Cells / Q000166:cytology; D004848:Epithelium / Q000196:embryology; D007150:Immunohistochemistry; D008648:Mesoderm / Q000166:cytology; D008854:Microscopy, Electron; D009300:Nasal Septum / Q000166:cytology / Q000196:embryology; D010159:Palate / Q000166:cytology / Q000196:embryology*; D011817:Rabbits
D002863:Chromogenic Compounds