Okada S, Ohta Y, Nishimura K, Matsushita J, Nakamura M
Department of Anatomy, Osaka Dental University, Japan.
Okajimas Folia Anat Jpn. 1990 Oct;67(4):231-41. doi: 10.2535/ofaj1936.67.4_231.
The ultrastructure of the ameloblasts in the rabbit major incisor was investigated previously by Okada (1983) and the amelogenetic process was classified into six zones/stages. The present paper deals with changes in the microvascular architecture and ultrastructure of the blood capillaries in proportion to the amelogenetic process in the upper major incisor of the rabbit utilizing the acryl plastic injection method. Three different vascular layers were observed in the periodontal spaces of the major incisor of the rabbit. The inner vascular network consisted of a capillary network supplying the enamel organ and its meshes have vigorously changed during the amelogenesis. The capillary network was observed to be in the shape of a ladder with a continuous wall in the proliferation zone, to appear as round meshes with a fenestrated wall in the differentiation zone, as polygonal meshes with abundant fenestrations in the secretion zone, as ovoid meshes with fenestrations in the early maturation zone, and finally as coarse and avoid meshes with a continuous wall again in the late maturation and regression zones. In the intermediate layer, arterioles and venules were located close to the capillary network, and the arterioles were derived from the short and long branches of the anterior superior alveolar artery. In the outer layer, a sinusoid network was observed to be in contact with the alveolar wall and received blood from the capillary network as well as venous vessels in the alveolar bone. The ladder-shaped capillary network mentioned above was thought to represent an intermediate form towards the succeeding zone, in which the round meshes may be suitable for supplying the nutrient elements that are needed in the differentiation of the inner enamel epithelial cells. The polygonal and ovoid meshes may be favorable for the transport of various necessary metabolic materials that are involved in the enamel ground substance formation and calcium deposition within a very short period.
冈田（1983年）曾对兔上颌切牙成釉细胞的超微结构进行过研究，并将釉质形成过程分为六个区域/阶段。本文利用丙烯酸塑料注射法，研究了兔上颌切牙釉质形成过程中微血管结构及毛细血管超微结构的变化。在兔上颌切牙的牙周间隙中观察到三层不同的血管层。内层血管网络由供应釉器的毛细血管网组成，其网孔在釉质形成过程中发生了显著变化。在增殖区观察到毛细血管网呈梯状，壁连续；在分化区呈圆形网孔，壁有窗孔；在分泌区呈多边形网孔，有丰富的窗孔；在早期成熟区呈椭圆形网孔，有窗孔；最后在晚期成熟和退缩区又呈粗大且不规则的网孔，壁连续。在中间层，小动脉和小静脉靠近毛细血管网，小动脉源自上前牙槽动脉的长短分支。在外层，观察到一个血窦网络与牙槽壁接触，并从毛细血管网以及牙槽骨中的静脉血管接收血液。上述梯状毛细血管网被认为是向后续区域发展的一种中间形式，其中圆形网孔可能适合为内釉上皮细胞分化所需的营养元素提供供应。多边形和椭圆形网孔可能有利于在极短时间内运输参与釉质基质形成和钙沉积的各种必要代谢物质。
