上皮小体摘出ラット切歯の乳頭層の変化に関する研究
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概要
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This study was performed to elucidate the role of the papillary layer in enamel formation. One hundred twenty-five Wistar strain male rats, 6 weeks old, were used in this experiment. Seventy-three rats under went parathyroidectomy and the decrease of Ca concentration and increase of P concentration in serum were confirmed. Vitamin D_3 were administered for functional improvement and its effects were observed. Detailed light and transmission electron microscopic observations were made of the ameloblasts, papillary layer and capillaries of the rat incisor enamel organ at the stage of enamel maturation. The following results were obtained. 1. Normal papillary layer The papillary cells at the maturation stage had irregular shapes. The papillary cells were connected with each other as well as with the proximal ends of the ameloblasts by desmosomes. The extracellular space between papillary layer cells was occupied by interdigitating microvilli. The endothelial wall of the capillaries except for the nuclear portions became very thin and fenestrations of about 60nm in diameter were clearly observed. The majority of the fenestrations were closed by thin diaphragms. 2. GBHA staining Four transverse and oblique lines on the superficial layers of enamel were observed in both the experimental and control groups. 3. Parathyroidectomized groups 1) Many degenerated cells appeared at the RA portion in the ameloblasts. There were portions, inhibiting the calcification was confirmed by the Azan staining in two layers, superficial and deep layers of the enamel at the stage of maturation. 2) The cells at the papillary layer were atrophied and the extracellular spaces were dilated. The mitochondria were localized on the side of the blood vessels in parts. 3) The capillaries showed a disturbance of structures with two layers, with considerably different course from that in the control group. Many of the fenestrations were not closed by thin diaphragms. 4) The iron-containing pigments were small and few, but there was the normal release on the superficial layer of enamel. 4. Vitamin D_3 administration groups 1) The papillary layer cells and ameloblasts were similar to those under control conditions, but cells were partially degenerated. 2) The majority of the fenestrations were closed by thin diaphragms. 3) The iron-containing pigments were similar to those in control animals. The pigments were retained in the papillary layer from the early stage of maturation and in the ameloblasts after the transitional stage. Thereafter, they were quickly released on the superficial layer of enamel, but more pigment was retained by the degenerated ameloblasts and papillary layer cells than that in the control group.
- 福岡歯科大学学会の論文
- 1994-09-30
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- 上皮小体摘出ラット切歯の乳頭層の変化に関する研究
- 上皮小体摘出ラット切歯の乳頭層の変化に関する研究