Yoshiaki Kishi

A scanning electron microscope study of the blood vessels of dog pulp using corrosion resin casts

Summary Vascular casts of dog pulps using a low-viscosity synthetic resin were examined stereoscopically under the SEM. The corrosive resin cast method provides a way to view the detailed network arrangement of pulpal microvascular beds. The anatomical heterogeneity of the vascular network within the pulp, for instance, the coronal vs the apical and the peripheral vs the central pulps, is clearly shown. The study also shows numerous apical foramens with each foramen occupied by only one type of vessel, either an arteriole or a venule. The presence of the arteriovenous anastomosis, the venous-venous anastomosis, and the U shaped arterioles may be features unique to the pulpal vascular network.

Vascular architecture of cat pulp using corrosive resin cast under scanning electron microscope

Vascular casts of cat premolar pulps in various stages of growth were made by injection of low-viscosity resin into the pulpal blood vessels. Examination under a scanning electron microscope revealed that, in the young pulp, the main arterioles ascend in the center of the pulp and venules run along the side of the root canal space. The subodontoblastic vascular plexus of the pulp could be distinguished by its characteristic three layers: 1. the terminal capillary network located in the odontoblastic layer; 2. a second layer of the capillary network which is composed of pre- and postcapillaries running parallel to each other; and, finally, 3. the venular network which has a lattice type appearance. The pulp cavity is reduced in size with age (maturation stage), in which the characteristic three vascular layers are changed into a one-layer coarse terminal capillary network which converges directly with the main venules. At this stage the blood vessels, especially the main venules, are also fewer in number.

Three-Dimensional SEM Study of Arteriovenous Anastomoses in the Dog’s Tongue Using Corrosive Resin Casts

Arteriovenous anastomoses (AVAs) participate in the regulation of blood flow. Although it has been speculated that AVAs in the dogs tongue play a role in the regulation of the body temperature, no published work is available on the structural characteristics of AVAs in the dogs tongue. The purpose of the present investigation was therefore to determine the frequency of AVAs and their structural characteristics by the fabrication of vascular corrosive resin casts and examination under a scanning electron microscope. This method permitted not only the visualization of the three-dimensional characteristics of AVAs, but also a clear differentiation between arterioles and venules. The total number of AVAs in the mucosal lamina propria of the dorsum of the left tongue half was 2,292. Several essential types such as S-shaped, hook-shaped, straight, bibranching and Y-shaped AVAs were observed, of which the S-shaped and similar types constituted the overwhelming majority; Y-shaped types have never been reported heretofore. This study also revealed that the locations where AVAs were most often distributed were, in descending order of frequency, the tip, the corpus and the root area of the tongue. This high frequency and strategic location of AVAs in the tongue strongly indicate that AVAs of the dogs tongue participate in the thermal regulation.

A study of leukocyte extravasation in early inflammatory changes in the pulp

The pathway of leukocyte extravasation in experimentally induced acute pulpitis in dog teeth was investigated using light microscopy, transmission electron microscopy, freeze-fracture, and corrosion resin casts examined under a scanning electron microscope. Leukocytes emigrate from the lumen of the vessel through the intercellular junction of the endothelium primarily in the venular network located in the center of the pulp. Once complete passage through the vessel into the interstitial space is made, the leukocytes travel into the perivascular connective tissue and beyond.

Changes in the vascular network of the oral epithelium and reduced enamel epithelium during tooth eruption.

The purpose of this study was to examine the vascular network beneath the reduced enamel epithelium (REE) and oral epithelium (OE) during tooth eruption. Using the corrosive-resin casting method, vascular resin casts were prepared from premolar and molar teeth of the dog and examined by scanning electron microscopy. The vascular network beneath the REE is arranged in two layers, an inner layer consisting of a dense capillary network and an outer layer composed primarily of arterioles and venules. Throughout tooth eruption, the configuration of the vessels of the inner layer is continually changing from a network of capillary loops to a fishnet pattern, whereas the arrangement of the vessels of the outer layer remains fairly constant. When the crown emerges into the oral cavity, leakage of resin from the vessels provides evidence of increased vascular permeability, suggesting the presence of inflammation within the marginal gingiva. When root development is nearly complete, the vascular network adjacent to the REE becomes continuous with that of the OE. The inner margin of the free gingiva receives its blood supply from this network, and the vessels of this network also give off branches which anastomose with the capillary network of the periodontal ligament.

A Study of Interface Bone and Microcirculation of Implants under Occlusion.

インプラント界面骨と微小循環について, 実験的にビーグル犬下顎骨にチタン・インプラント (ADSインプラント) を植立, 上部構造を装着して9カ月間咬合させた後, 主に骨付き微細血管鋳型法を用いて試料を作製, これを走査型電顕で観察した。その結果, インプラントと接する界面組織は骨ならびに小塊状の線維性結合組織であった。この小塊内には特異な分布形態・走行を示す毛細血管が小数分布し, この毛細血管と近接する界面骨には骨吸収窩 (ハウシップ窩) が観察された。これに対して血管の存在しない界面骨の表面には, ハウシップ窩は観察されなかった。いずれにせよ, インプラント界面全体に分布する毛細血管は極めて少なかった。一方, 界面骨の裏側, すなわち骨髄側には近接して特異な毛細血管網が密に分布する箇所があり, この部位の骨表面には無数のハウシップ窩が観察された。以上のことから, 界面骨の厚さは骨髄側でコントロールされ, 一度形成された界面骨の代謝活性は極めて低く, 環境変化に素早く対応することが出来ない状態にある, ということが微小循環の面から示唆された。