Shu-Qi Zhong, Yu-Dong Xu, Yun-Fang Zhang, Ya-Fang Zhang, Li-Si Hai, Feng-Cai Tang, ¹Department of Histology, Harbin Medical University, Harbin 150086, Heilongjiang Province, China
²Department of Anatomy, Harbin Medical University, Harbin 150086, Heilongjiang Province, China
Dr. Shu-Qi Zhong, female, born on October 28, 1949 in Ber Li City, Heilongjiang Province, graduated from Harbin Medical University in 1975, now associate professor of histology, major in lymphatics, having 31 papers and 3 books published.
*Supported by the National Natural Science Foundation of China, No. 39070462
Correspondence to: Dr. Shu-Qi Zhong, Department of Histology, Harbin Medical University, 157 Baojian Road, Harbin 150086, Heilongjiang Province, China
Telephone: +86-451-6669576
Received: 1998-04-20

Subject headings: stomach; corrosion casts; lymphatics; three-dimensional structure

Zhong SQ, Xu YD, Zhang YF, Zhang YF, Hai LS, Tang FC.Three-dimensional structure of lymphatics in rabbit stomach.
World J Gastroenterol,1998;4(6):550-552

INTRODUCTION
Recently, the stomach lymphatics have been studied, but there are different opinions on the lymphatic distribution of the stomach layers^［1-6］. And the academic thesis have not been reported in China discribing the three-dimensional organization of the stomach lymphatics and revealing the correlation of the three-dimensional organization with the two dimensional.
      In our study in the rabbit with the lymphatic corrosion cast with Mercox and semithin section methods we investigated the relationship of the three-dimensional organization with the drainage of the stomach lymphatics, which may provide the evidences of lymphology, pathology and the clinical medicine.

MATERIALS AND METHOD
Twelve rabits of both sexes were used, two of them, undergone the procession of the seemitin section of electron microscopy, were observed with light microscopy. The other ten were used for the lymphatic corrosion casts. The Mercox (CL-2B-5, Japan Velene Hospital, Tokyo, Medium) diluted to 25%-30% (V/V) with methyl methacrylate monomer was injected in and around the mucosal submucosal, layers of the stomach. Shortly before the injection, a curing agent (MA. Japan Vilene Hospital Tokyo) was added to the injection medium to give a concentration of 1% (W/V) . The injected parts of the stomach were removed and placed in a hot water bath (60℃) for 3hrs. They were put in concentrated NaOH (15%-20%) at about 60℃ until tissue elements were completely corroded away. The lymphatic corrosion casts cut into blocks. The blocks were observed under a SEM (S-520) (with an accelerating voltage of 10-15kv).

RESULTS AND DISCUSSION
The lymphatic of mucosal and submucosal layers
The samples filled with resin which were in the mucosal and the submucosal layers clearly showed the three-dimensional organization of the lymphatic capillaries and the lymphatics. There was a layer of the lymphatic capillary network in the deep layer of the tunica mucosa between the bottoms of gastric gland and the muscularis mucosa. The networks extended short tube with blind ends into gastric glands. The tubers were called intergland circular cones. The The cones were 20μm-30μm in diameters. The cones were round, hook, V and finger in shap. In the cardia and the fundus of the stomach the cones were sparse and connected to the lymphatic capillary networks of the tunica mucosa. In the body of the stomach 2 or 3 circular cones were connected in one group. The roots of the circular cones were connected to the sinus (50μm-60μm in diameters), then drained to the lymphatic capillary networks of the tunica mucosa (Figure 1).
      Donini has observed the lymphatic capillary networks of the subepithelium were in the stomach pylorus. We observed the lymphatic capillaries between the bottoms of the tunica mucasa gland and the muscularies mucosa, but did not observe the lymphatic capillaries were in the subepithelium. Our observations were smilar to Han′s studies^［5］. We found the lymphatic capillaries were in the tunica mucoa, but no thick lymphatics were there. A large number of lymphatic capillaries and lymphatics were found in the tela submucosa. The lymphatic capillaries formed a coarse network. The lympahtics (vessels) also formed a coarse plexus. The corrosion casts of the lymphatic clearly showed the three dimensional organization of the lymphatics. The diameter of the lymphatic capillary was 10μm-30μm, but the lymphatic vessel′s diameter was 30μm-100μm. The sixe of the meshes of the lymphatic vessels were varied and interconnected, they were triangular oval and polygon shape. The semithin sections also showed rich lymphatic capillaries and lymphyatic vessels in the stomach tela submucosa. On the surface of the lymphatic casts, we found marked constrictions characteristric of bicuspid valves (Figure 2).

The lymphatics of the tunica muscularis
A rich lymphatic capillaries and lymphaties were found in the stomach tunic muscularis. Some the lymphatic capillaries of 7μm-30μm in diameter extended the short branches with blind ends. The diameter of the lymphatic was 30μm-80μm. Between three layers of the muscular there were the lymphatic capillaries and the lymphatic vessels. The lymphatics were string of beads in shape and interconnected to plexus. There were break ends of the anastomotic channels to the superficial and the deep part from the lymphatics of the tunic muscularis. It suggested that the lymphatics of the tunica muscularis were interconnected with both the lymphatics of the tela submucosa and with the lymphatics of the tunica serosa. The surface of the lymphatic casts in the tunica muscularis there were folds which run parelled to the lymphatic major axis. The imprints of endothelial nuclei were denser than other layers. On the surface, we could see the transverse imprints which were induced by the smooth muscle contraction. Between the lymphatic capillaries and lymphatic vessels of the tunica muscularis there were the anstomotic channels which existed in each layer perimysium. The lymphatics and the lymphatic capillaries of the tunica muscularis were seen in the histological sections.
      Octrovekhov thought that there was not any lymphatic capillary. But Nariadchikova pointed out that the lymphatic vessels and the lymphatic capillaries of the tunica muscularis only existed among the three layer′s muscularis not in each muscular layer. Our experiment proved that in the connective tissue there were both lymphatic capillaries and lymphatic vessels in each smoth muscularis layer. We also observed that there were the lymphetic capillaries among perifascicular parts of each muscular layer.

The lymphatics of the tunica serosa
There were both the lymphatic capillaries and the lymphatic vessels in a deep part of the tunica serosa (Figure 3). The meshes of the lymphatic capillary nextwork and the lymphatic plexus in the layer were larger than those of the ttela submucosa and the tunic musecularis. The meshes presented in willow leaf, oval or trianglar shape. The lymphatic capillaries and the lymphatic vessels were also observed in the semithin sections of the layers under the light microscopy.

Figure 1 The intergland circular cones of tunica mucosa (m) the lymphatic capillaries (c) and the lymphatics (L) of the tela submucosa. SEM×150
Figure 2 The lymphatic networks of the tela submucosa. The constriction (b) of the cast surface presenting the bicuspid valves; the ovar or fusiform indentations (o) presenting the endothelial nuclei of the lymphatic. SEM×550
Figure 3 The lymphatic capillaries (c) and the lympatic vesseles (L) of the tunica serosa. The constriction (b) presenting the impression of the bicaspid valves. SEM×200

      Donin reported that only in the curvatura veutriculi minor and major did the lymphatic capillaries of the tunica serosa exist. Rakhan tought the lymphatic capillaries of the tunica serosa only existed in the parts of pylorus. Ohtani^［3］ pointed out that only the lymphatic vessels existed in the longitudinal muscle layer. In our lymphatic casts and semithin setions we observed both the lymphatic capillaries and the lymphatic vessels existed in the tunica serosa.

The drainage correlation of the lymphatics of all the layers.
The lymphatic, capilaries of the tunica mucosa
        ↓
The lymphatic capillaries of the tela submucosa→ The lymphatic vessels of the tela submucosa
                       ↓
The lymphatic capillaries of the tunica muscularis→The lymphatic vessels of the tunica muscularis
                       ↓
The lymphatic capillaries of the tunica serosa→The lymphatic vessels of the tunica serosa
The aggregate lymphatics vessels
  ↓
The part lymph nodes

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