| Part I: The distribution of arachnoid granulations and morphological characteristics in rabbitsObjective: To explore the distribution of the arachnoid granulations and research its morphological characteristics in rabbits.Materials and methods: 20 New Zealand rabbits were used for study. 6 of them were injected 0.6ml methylene blue into cisterna magna after intravenous anesthesia and kept head down. Two hours later, the rabbits were decapitated and cranial vault was removed. The distribution of the arachnoid granulations were observed under microscope; 8 of them were used for the HE staining to explore the distribution of the arachnoid granulations and master its macroscopic Structure in rabbits. Rabbits were perfused by 4% paraformaldehyde solution and killed by decapitation using a guillotine method. Blocks of tissue containing arachnoid granulations were made serial sections from left to right. The thickness of every sections was 0.5μm, obtained 1 in every 5 sections. Sections were carried out HE staining and observed under the microscope. 6 of them were used for electron microscope study. The specimen were observed on the surfacial and internal ultrastructure by scanning electron microscopy and transmission electron microscopy .Results:1 The subarachnoid space,optic nerve sheath,transverse sinus,superior sagittal sinus were stained blue after injection of methylene blue into cisterna magna. Methylene blue predominantly located in transverse sinus, indicating arachnoid granulations exist in transverse sinus.2 Arachnoid granulations can be divided into the neck, body and bottom according to HE staining.It show different shapes with spherical,lobulated, cauliflower-like and so on.3 Scanning electron microscopy showed individual and clustered arachnoid granulations with protrusions showing different sizes and shapes on it.There were many pores at the top and lateral of arachnoid granulations.4 TEM observed many pinocytotic vesicles,large vacuoles and microvilli on surface of epithelial cells in AGs. There are many extracellular spaces in AG. It can also observe so many cell-cell junctions between them. Connections between epithelial cells in AG, some are tightly connected, some are loose,while there are expansion in some places.Conclusion:1 The distribution of the arachnoid granulations in rabbits were mainly located in transverse sinus.2 There were individual and clustered arachnoid granulations in rabbits, sharing similar morphology with humans. Arachnoid granulations can be divided into neck,body and bottom; with protrusions showing different sizes and shapes on it. There were many pores at the top and lateral of arachnoid granulations. Arachnoid granulations showed different shapes: spherical,lobulated,cauliflower-like and so on.3 Vacuoles and micro-pinocytic vesicles and large extracellular pool were observed on surface of epithelial cells in AGs. These structures may play an important role in the cerebrospinal fluid circulation. Extracellular space take part in passive transport of cerebrospinal fluid.While vacuoles and micro-pinocytosis involved in active transport of cerebrospinal fluid.PartⅡ: The expression of TGF-β1 in arachnoid granulations after Subarachnoid hemorrhage in rabbitsObjective:Establish the model of subarachnoid hemorrhage in rabbits; Research expression of TGF-β1 within arachnoid granulations after SAH; Explain the pathological changes and clarify its mechanism. Materials and methods:36 New Zealand rabbits were randomly divided into control group and experimental groups.6 of them was used for control group; The experimental groups were divided into A,B,C,D,E and F subgroups, respectively represent for 1 days,3 days,5 days,7 days,10 days,12 days after subarachnoid hemorrhage. each subgroup contained 5 rabbits. When rabbits were fully anaesthetized.Percutaneous puncture the cisterna magna were performed when cerebrospinal fluid slowly outflowed.The experimental groups were taken autologous blood 0.5 ml/kg from the median artery of the rabbit's ear and were slowly injected into cisterna magna.While the control group were injected with saline only after successful puncture.It should draw equivalent cerebrospinal fluid before injected blood or saline into cisterna magna.Experimental groups were respectively sacrificed using a guillotine method at 1,3,5,7,10,12 days and the control group were also respectively killed at time above-mentioned. The cranial vault was immediately removed and obtained the blocks of tissue containing AG. Immunohistochemical staining was executed to observe the expression characteristics of TGF-β1 in all groups.Result:Arachnoid granulations in control group seldomly showed TGF-β1 positive expression while the experimental groups were obvious.Cytoplasm contained brown particles while nucleus was stained blue with oval or lobulated. From 1 to 5 days gradually increased, reached the peak at 5 days. expression of TGF-β1 reduced in AG at 7days , but still higher than control group. However,The expression of TGF-β1 was persistent at 12 days. The experimental groups were compared with control group by t-test, There was statistical significance (P<0.05). The Comparison between groups were tested by SNK method, There was statistical significance between 5 days with rest groups (P<0.05).Conclusion:1 Autologous arterial blood were slowly injected into cisterna magna,and successfully established the model of subarachnoid hemorrhage in rabbits.2 The expression of TGF-β1 in arachnoid granulations increased obviously after Subarachnoid hemorrhage in rabbits,We suppose that high expression of TGF-β1 was relevant to the development of communicating hydrocephalus.
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