A scanning electron microscope study of the capillary loops

Transcription

1 Jpn.J.Oral Biol.,28: ,1986. A scanning electron microscope study of the capillary loops of oral epithelial papillae using corrosive resin casts I.Gingiva,alveolar mucosa,and buccal mucosa Yoshiaki Kishi,Tuncheng Wang,Seigyo So,Eiichi Yoshizaki and Kazuto Takahashi Dept.of Oral Anatomy,Kanagawa Dental College 82 Imaoka,Yokosuka,Kanagawa,Japan Key words:sem,resin cast,capillary loops Introduction Various methods and techniques1-7) have been used to study the blood vessels of the oral tissues and organs of man,as well as those of experimental animals.although numerous studies have demonstrated the arrangement of the vascular network of the oral epithelial papillae,they represented the vascular network only in two-dimentions. A detailed analysis of the three-dimentional vascular arrangement in the oral epithelial papillae has not yet been reported. The purpose of this study is to describe the various types of networks distributed in the oral epithelial papilae of the dog in threedimentions using the injection of low-viscosity resin into the blood vessels,and then examining them with a scanning electron microscope (SEM). Materials and Methods Five adult dogs were anesthetized with sodium pentobarbital (0.5 ml/kg) and the bilateral common carotid arteries were cannulated.a sufficient amount of Ringer's saline solution was perfused into the arteries until from the changes in color,the jugular veins appeared to be cleared of blood.after saline perfusion,2% glutaraldehyde in phosphate buffer was perfused to fix the vessels.after fixation,other perfusion tubes were inserted into the bilateral external ca.- rotid arteries through which the colored synthetic resin (methyl methacrylated:melcox) was injected until the whole gingiva was perfused with the resin.after polymeriza- tion, the specimens were decalcified with 10% nitric acid and the soft tissues were dissolved with 10% potassium hydroxide. The completed specimens were washed thoroughly with tap water at Ž and freezedried.after being coated with platinumpalladium, the corrosive resin cast was examined with the SEM. Results and Discussion (1)Gingiva Gingiva can be divided,primarily,into the outer gingival epithelium and the inner gingival epithelium which faces the tooth surface.we have reported previously on the development of the vascular network beneath the inner gingival epithelium (1982)8) using corrosive resin cast with SEM.The outer gingival epithelium may be classified according to its function as a masticatory mucosa which consists of thick epithelium and tall papillae. Fig. 1 shows the capillary network closely subjacent to the outer gingival epithelium. An absolutely different arrangement of vascular network below the mucogingival junction (arrow) can be identified,that is, the vascular network beneath the alveolar mucosa.the arteries originateing from these run along the alveolar bone surface cross the alveolar ridge and enter the gingiva where they branch and give off two groups:

2 240 Jpn.J.Oral Biol.,28: ,1986. one group runs toward the inner gingival epithelium and the other along the curvature of the outer gingival epithelium.the latter gives off numerous branches again toward the superficial surface of the outer gingival epithelium as they run on a course p below the superficial surface.this leads to the formation of an arterial and venule network (so called lamina propria network) at a level beneath the base of papilla.the venules of this network have a diameter of approximately ƒê for arterioles and p for venules.further, branches issuing from the lamina propria net- work form a layer of the vascular network at a level at the base of the papilla (the so called subpapillary capillary network).these arterioles and venules run parallely with each other and form a characteristic vascular network,so called subpapillary network (Fig.2/3).Then, fine branches from the subpapillary network into the papillae and form capillary loops. A capillary loop of the gingiva,primarily, consists of an ascending arterial capillary and a descending venular capillary,while the loop marked with an asterisk is ( ) composed of two ascending capillaries and one descending capillary.the loops in the marginal gingiva have the same arrangement,but the diameter of the descending one is larger (Fig.2). In the route from the free gingiva to the attached gingiva,the height of the loops become shorter and the space between the two roots of a loop also becomes narrower (Fig.3). (2) Alveolar mucosa Located apical to the mucogingival junction is the mobil alveolar mucosa.the vascular network beneath the alveolar mucosa consists of a lamina propria vascular network in which the venules,similar to that in gingiva,are conspicuously developed and a subpapillary capillary network which, because of its more dense arrangement, is quite different in its morphological arrangement from the gingiva. Capillary loops are also present in the alveolar mucosa network, however, they appear extremely low in height and few in number. While the network beneath the alveolar mucosa a little apical to the mucogingival junction,appears to be in a pattern of continuous wave-like juxtaposed layers, spaced and mesiodistally. (3) Buccal mucosa In buccal mucosa,the capillary hair-pin loops are simple,few and short in height. A subpapillary vascular network which originated from a capillary surrounds a buccal gland in the position marked with an asterisk ( ) can be seen (Fig.5).The difference between the diameters of the arteriolar blood vessels and venular ones of the subpapillar network is quite small,and is in contrast, unsimilar to that of the gingival.as previously described,the arterioles (20ƒÊ) with venules (40ƒÊ) in the arterio-venular network (lamina propria netwoek), have a ratio of 1:2(Fig.6),while that of the gingiva is 1:3. There is a paratid papilla around the orifice of the excretory duct of parotid gland, Fig. 7 illustrates many tall capillary loops which form several concentric wheels surrounding the orifice of the excretory duct.accordingly, a characteristic concentrical wave-like pattern can be clearly identified.in conclusion, the capillary loops both gingiva and buccal mucosa have the same hair-pin loop arrangement,but the difference between these two vascular networks is the meshwork arrangement,i.e.,the density,size,and the difference in diameter between the arterioles and venules of the lamina propria vascular network also can be observed. References 1) Boling,L.R.:Blood vessels of the dental pulp.anat.rec.82:25-37, ) Prichard,M.M.L.and Daniel,P.M.:Arterio-venous anastomoses in the tongue of dog.j.anat.87:66-74, ) Saunders,R.L.de C.H.:Microradiographic studies of human adult and fetal dental pulp vessels.x-ray Microsc.Microradiography.1: , ) Aoyagi,F.:Microangiogram of human dental pulp vessels.bull.tokyo dent.coll.5: 59-69, ) Egelberg,J.:The blood vessels of the dentogingival junction.j.periodont.res.1: ,1966.

3 Y.Kishi et al.:sem study of capillary loops of oral epithelial papilla.i ) Kramer,I.R.H.:The distribution of blood vessels inthe human dental pulp.in Finn,S. B.,ed.Biology of the dental pulp organ:a symposium.university,ala,university of Alabama Press, ) Hock,J.and Nuki,K.:A vital microscopy study of the morphology of normal and inflamed gingiva.j.periodont.res.6:81-88, ) Kishi,Y.:The development of the vascular network under the inner epithelium of the dog gingiva using resin casts and scanning electron microscope.jpn.j.oral Biol.24: ,1982. Explanation of figures Fig.1 External view of the vascular architecture of the gingiva (G) and the alveolar mucosa (AM).White arrow and Cr represent mucogingival junction (MGJ) and crown,respectively. Fig.2 A high magnification of a part of the marginal gingiva of Fig.1,showing that the capillary loops of the gingiva are composed of numerous hairpin-loops.the capillary network underneath the papilla consist of arterialcapillaries (a) and venular capillaries (v). Cr:crown space,mg:marginal gingiva. Fig.3 A high magnification of the capillary loops located around the mucogingival junction (MGJ) clearly demonstrating that underneath the papilla the capillary network of gingiva (G) is quite different from that of alveolar mucosa (AM).(A) and (V) represent the arteriole and venule of the lamina propria network respectively.mgj: mucogingival junction Fig. 4 A high magnigication of the capillary loops of alveolar mucosa.a: arteriole,v:venule. Fig. 5 Part of the capillary network(subpaillary capillary network;spcn) seen underneath the papilla of the buccal mucosa.( ) represent the duct of a buccal gland which is surrounded by many capillary networks. Fig.6 A sagittal section of the vascular network of the buccal mucosa.spcn: subpapilla capillary network,a:arteriole,v:venula. Fig.7 The vascular network of the parotid papilla,showing that many capillary loops form several concentric wheels and surround the orifice of the duct ( )

4 242 Jpn.J.Oral Biol.,28: ,1986.

5 Y. Kishi et al.: SEM study of capillary loops of oral epithelial papilla. I.

6 244Jpn. J. Oral Biol.,28: , 1986.