Spatial and temporal distribution of Ki-67 proliferation marker, Bcl-2 and Bax proteins in the developing human tooth

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• 作者：Danijela Kalibović ; Govorko ; Tina Beč ; ić ; Katarina Vukojević ; Snjež ; ana Marde&#x161 ; ić ; -Brakus ; Dolores Bioč ; ina-Lukenda ; Mirna Saraga-Babić
• 关键词：Human embryo ; Tooth development ; Ki-67 ; Bax ; Bcl-2
• 刊名：Archives of Oral Biology
• 出版年：2010
• 出版时间：December 2010
• 年：2010
• 卷：55
• 期：12
• 页码：1007-1016
• 全文大小：683 K

文摘

Objective

To investigate the spatial and temporal expression of proliferation Ki-67 marker, pro-apoptotic Bax and anti-apoptotic Bcl-2 proteins during early development of the human tooth.

Materials and methods

Histological sections of eight human conceptuses, 5–10 postovulatory weeks old, were used for immunolocalization for Ki-67, Bax and Bcl-2 markers. Quantification was performed by calculating the fraction of Ki-67 positive cells, expressed as a mean ± SD, and analysed by Mann–Whitney test, Kruskal–Wallis and Dunn's post hoc test.

Results

In 6th–7th developmental weeks, the tooth germ and dental crest contained 37 % of proliferating cells, which increased to 40 % in the 8th week, and then decreased to 15 % in the 10th week, whilst the proliferation in the ectomesenchyme subsequently dropped from 37 % to 23 % . Epithelial parts of the enamel organ displayed similar proliferation activity (31–36 % ), dental crest 10 % , whilst enamel knot showed no proliferating activity. The tooth ectomesenchyme contained more proliferating cells (50 % ) than the jaw ectomesenchyme (35 % ), and both dropped to 28 % in the 10th week. Ectomesenchyme between the tooth germs contained 23 % , whilst the jaw ectomesenchyme contained 15 % of proliferating cells. Bcl-2 expression had following pattern: strong in proliferating cells, moderate in tooth germs and dental crest, and weak in the ectomesenchyme. Bax co-expressed with Bcl-2 in the tooth germ and dental crest. In the reticulum and inner enamel epithelium Bcl-2 had prevalent expression, whilst Bax prevailed in the outer enamel epithelium and tooth ectomesenchyme.

Conclusions

Proliferating cells most likely influence growth of the tooth germ, Bcl-2 affects proliferation and differentiation of specific cell lineages, whilst Bax influences process of cell death.