The distribution and ultrastructure of the forming blood capillaries and the effect of apoptosis on vascularization in mouse embryonic molar mesenchyme.
Vascularization is essential for organ and tissue development. Teeth develop through interactions between epithelium and mesenchyme. The developing capillaries in the enamel organ, the dental epithelial structure, occur simultaneously by mechanisms of vasculogenesis and angiogenesis at the onset of dentinogenesis. The vascular neoformation in the dental mesenchyme has been reported to start from the cap stage. However, the mechanisms of vascularization in the dental mesenchyme remain unknown. In the hope of understanding the mechanisms of the formation of dental mesenchymal vasculature, mouse lower molar germs from embryonic day (E) 13.5 to E16.5 were processed for immunostaining of CD31 and CD34, terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) and transmission electron microscopy (TEM). In addition, the role of apoptosis for the vascularization in dental mesenchyme was examined by in vitro culture of E14.0 lower molars in the presence of the apoptosis inhibitor (z-VAD-fmk) and a subsequent subrenal culture. Our results showed that CD31- and CD34-positive cells progressively entered the central part of the dental papilla from the peridental mesenchyme. For TEM, angioblasts, young capillaries with thick endothelium and endothelial cells containing vacuoles were observed in peripheral dental mesenchyme, suggesting vasculogenesis was taking place. The presence of lateral sprouting, cytoplasmic filopodia and transluminal bridges in the dental papilla suggested angiogenesis was also occurring. Inhibition of apoptosis delayed the angiogenic vascularization of the dental papilla. Therefore, these data demonstrated that molar mesenchyme is progressively vascularized by mechanisms of both vasculogenesis and angiogenesis and apoptosis partially contributes to the vascularization of the dental papilla.
Key Laboratory of Oral Biomedicine of Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, Hubei, People's Republic of China, 430079.
Guohua
G
Yuan
Li
L
Zhang
Guobin
G
Yang
Jingwen
J
Yang
Chunyan
C
Wan
Lu
L
Zhang
Guangtai
G
Song
Shuo
S
Chen
Zhi
Z
Chen
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D018952:Antigens, CD34 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D002196:Capillaries / Q000196:embryology / Q000648:ultrastructure*; D005455:Fluorescent Antibody Technique; D020287:In Situ Nick-End Labeling; D008648:Mesoderm / Q000098:blood supply* / Q000166:cytology / Q000196:embryology* / Q000648:ultrastructure; D051379:Mice; D008813:Mice, Inbred ICR; D008963:Molar / Q000098:blood supply* / Q000166:cytology / Q000196:embryology* / Q000648:ultrastructure; D018919:Neovascularization, Physiologic / Q000187:drug effects; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D014083:Tooth Germ / Q000166:cytology / Q000187:drug effects / Q000196:embryology; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
D000590:Amino Acid Chloromethyl Ketones; D018952:Antigens, CD34; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D042461:Vascular Endothelial Growth Factor A; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone