| Objective: 1. To observe the histological architecture, morphological features and record the results of quantitative analysis of atriventricular node (AVN) of guinea-pigs so as to provide morphological evidences for cardiac electrophysiology.2. To observe the relationship among the types of collagenous fibres, content and aging changes of atrioventricular node of guinea-pigs in order to study the rule of the growth of atriventricular node and provide the biological data in the study of the physiological function of atriventricular node.Materials and Method: Hybrid guinea-pigs were used in the experiment. According to their age, they were divided into three groups: baby group (1-2 months old), young group (6-10 months old) and old group (12-15 months old). Cardiac nodal regions were cut for tissue slices. HE and Masson staining, collagen staining of immunohisto chemistry and figure analysis were carried out. The position, the morphology and the histological architecture of the nodal regions was observed under the optical microscope and the size and bcation of the AVN were measured. Quantitative analysis was don eon the cells and the intercellular substance of atriventricular node with the device of figure analysis . Results: 1. The AVN of guinea-pigs were located within koch trignale. The locations were in the front, back and lower parts. The average length was 2.40± 0.61mm, The average height was 1.42 ±0.33mm and the average thickness was 0.76±0.12mm.2. Within the AVN, there were 3 kinds of conduction cells: P cells, transitional cells and Purkinje cells. The nonconduction cells generally include myocardium, fibroblast, tibre cells, myocardium cells and less fat cells. The histological architechre of AVN can be divided into the front nodal region and theback nodal region. There were cords between the two regions. In the front nodal region P cells were denser and arranged in lumps. In the back nodal region P cells were looser. T cells around P cells could be seen in both nodal regions.3. As the age increased, the ratio of the conduction cells in the AVN of guinea-pigs decreased, There were more mesenchyma and collagenous fibres. The ratio of collagen I and III changed, that was, collagen I fibres increased and collagen III fibres decreased comparatively.4. The results of figure analysis indicated:4,1 In the baby group the length ratio of P cells was 1. 41 ± 0. 20, the ratio of nuclear Vs cytoplasm was 0. 15 ± 0. 08, the area was359. 00 ± 71. 93 y. m2; the length ratio of T cells was 2. 90 ± 0. 50, the ratio of nuclear Vs cytoplasm was 0. 30 ± 0. 06, the area was 420. 90 ± 52. 32 U m\ the area of collagen I was6. 05 ± 0. 32 n m', the area of collagen III was 4. 13 ± 0. 25 μ m2.4.2In the young group the length ratio of P cells was 1. 28 ± 0. 17, the ratio of nuclear Vs cytoplasm was 0. 22 ± 0. 09, the area was271. 10 ± 67. 97 μ m2; the length ratio of T cells was2. 93 ± 0. 58, the ratio of nuclear Vs cytoplasm wasO. 25 ± 0. 05, the area was 478. 80 ± 58. 13 μ m2, the area of collagen I was7. 31 ± 0. 28 μm2, the area of collagen III was 3. 67 ±0. 36μ m2.4:3 In the old gronp the length ratio of P cells was 1. 25 ± 0. 16, the ratio of nuclear Vs cytoplasm was 0. 34 ± 0. 06, the area was257. 40 ± 39. 53 μ m2; the length ratio of T cells was2. 89 ± 0. 47, the ratio of nuclear Vs cytoplasm wasO. 22 ± 0. 06, the area was 478. 80±58. 13 U m2, the area of collagen I was 495. 40 ± 61.62 μm2, the area of collagen III was 2. 68 ± 0. 24 μ m2. Conclusion: 1. The AVN of guinea-pigs can be divided into the higher front part and lower back part and its shape is like a "dumbbell" lying flat. It can be divided into the front nodal region, the back nodal region and the region between these two. The cells are similar to man and other animals. The volumes increase and the location lowers as the age increases.2. The collagen fibres in the AVN of guinea-pigs mainly include Type I and III. As the age increases, the collagen fibre total and ratio...
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