| Subarachnoid hemorrhage (SAH), a common acute hemorrhagic cerebrovascular disorder, with an incidence rate of 10.5/100 thousand per year, accounts 9.0%-22.4% of total cerebrovascular disease. SAH is a dangerous disease with a mortality as high as 40%-50%, seriously impairs the patients normal life, as 46% patients are of cognitive dysfunction. The most common complications of SAH such as rehaemorrhagia, cerebral vasospasm and hydrocephalus can cause severity brain damage. Recently, there are mass of studies based on animal experiments and clinical trial, with the aim of interpreting pathology of the three complication of SAH and the underlied mechanism of their damaging effect on brain. However, it is failed to establish an uniform hypothesis based on these studies, which can explain all the events followed SAH.Cerebralspinal fluid (CSF) circulation, the so called the third circulation of human body, plays a crucial role in pathogenesy of the parenchymal central nervous system diseases such as intracranial hypertension, intracranial hemorrhages and SAH, as well as in prevention and cure of these disease. It is known to all,80%～85% of CSF is produced by choroid plexus, the major SCF producer located in cerebral ventricles, the structure changes of which will directly effect production of CSF and lead to followed disturbance of Cerebralspinal fluid circulation. Choroid Plexus, with capillary network as the central structure surrounded by connective tissues, is coating with ependyma epithelium, also called choroid epithelium, which processes active secrete function. Hippocampal formation consisting of hippocampus, subiculum, dentate gyrus and remnants of the hippocampus, plays a role in learning, memory and cognitive function, especially in short-term memory and space memory, in addition, it also involves in emotional behavior control and neuroendocrine. Furthermore, Hippocampal formation is still related to Alzheimer diseases(AD), temporal epilepsy and some psychiatric disorders. However, SAH and followed infuse of blood in subarachnoid space or cerebral ventricles, will effect normal CSF, and thus leads to structure changes of hippocampal formation and choroid plexus, as hippocampal formation located in cornu inferius ventriculi lateralis and medial wall, where it is only separated form CSF by a layer of ependyma.Object:In recent years, people pay more attention to the incidence of cerebral vasospasm in SAH causes acute brain injury research, but few people pay attention to other complications, and late onset of SAH caused by acute brain damage.Therefore, the present study, late of experimental subarachnoid hemorrhage in rats, lateral ventricle choroid plexus and hippocampus subtle and ultrastructural morphological ultrastructural characteristics, as experimental subarachnoid hemorrhage on the choroid plexus and hippocampal damage Mechanism to provide evidence of morphological experiments.Methods:1 experimental animal and drawing materialsChoose 35 adult SD rats, weighing 300～400g, either male or female, from the Experimental Animal Center of Hebei Medical University. The rats were randomly divided into the pre-experimental group (operation 5), the experimental group (operation 20) and control group (sham operation 10); pre-experimental group and the experimental group, with 6% chloral hydrate (0.5ml/100g) intraperitoneal injection of anesthesia, injecting 0.3ml autologous arterial blood in the cisterna magna, make simulation experimental model of subarachnoid hemorrhage. Pre-experimental group model is used to assess the situation drawn after 24 hours; the experimental group and control rats fed conventional, two months later drawn by aortic perfusion fixation for light and electron microscopy preparation of tissue samples.2 Sample preparation and observation for light microscope The aldehyde fixative fixed rat brain is given the concentration gradient from low to high ethanol dehydration, hyalinized xylene, embedded in paraffin, tissue sections, and then do routine HE staining and observe light microscopy; to show the lateral ventricle choroid plexus and hippocampus characteristics of the fine structure.3 Sample preparation and observation for SEMOrganize the fixed choroid plexus and hippocampus tissue samples, then prepare the conventional scanning electron microscopy sample. By scanning electron microscopy, reveal the characteristics of choroid plexus and hippocampal surface structure, and the effect of experimental subarachnoid hemorrhage on the surface structure.4 Sample preparation and observation for TEMTake aldehyde fixed choroid plexus and hippocampus tissue samples for routine transmission electron microscope sample preparation, observation on the ultra thin tissue slice of the transmission electron-microscope, reveal the choroid plexus and hippocampus of the ultrastructural features, as well as its experimental subarachnoid hemorrhage ultramicro organizational structure.Results:1 General observation showed that:The rats regained consciousness after apathetic, unresponsive, drowsiness, was curled up like head-down, water and food intake reduction, hair messy, and gradually recovered within 7 days. In preliminary experiments rats brain specimens were found in blood or blood clots in the subarachnoid space distribution, blood clots and more deposition are in the brainstem dorsal, cranial base and the basal cistern; cerebral hemispheres can be seen the surface of blood deposition.2 HE stained paraffin-embedded tissue sections by light microscopy observation showed that:(1) Pre-experimental group:subarachnoid became wider, large number of red blood cells can be seen in it. (2) Experimental group:the choroid plexus capillaries has no abnormal changes, slightly widened the gap around the connective tissue, a large number of vacuoles appeared in choroid plexus epithelial cells, cell body is irregularly shaped, the boundaries between cells is not clear. Ependymal surface of the hippocampus did not change in the structure. Slot in the hippocampus and polymorphic cell layer, we can see a small perivascular significantly widened. Pyramidal cell layer was thinner, reducing the number of cells, and cells arranged in disorder, the gap widened3 SEM observation showed that:a large number of crater-like depression appeared on choroid plexus epithelial cells, depression can also be found on normal epithelial cells surrounding some large number of secretory vesicles, and some cells microvilli atrophy, distorted or even fall off. Covered in the lining ependymal hippocampus, the cell surface is not abnormal cilia, and their microvilli or absence of a significant reduction.4 TEM observation showed that:a lot of endocytosis bubbles canbe seen in choroid plexus epithelial cells endocytosis, the cell body and nucleus are not inerratic, an increase in nuclear heterochromatin, cytoplasm shows a large number of primary and secondary lysosomes, may even see the swelling of the mitochondria. Ependymal cells in the hippocampus surface microvilli, secretory vesicles are not seen. A large number of lipid protein deposition in the perivascular nerve fibers, glial cells and pyramidal cells gap, the lipid protein deposition within the pyramidal cell is more rare. In the pyramidal cell layer, the gap widened between the pyramidal cells, cell density decreased.Conclusion:1 Single blood injection into the cisterna magna SAH model method can be successfully established, and the model is more consistent pathological changes, can provide a more realistic simulation of the pathological process of SAH.2 Experimental SAH resulted in the choroid plexus of lateral ventricle vacuolar degeneration, the reason for CSF circulation disorders due consideration. However, the choroid plexus of the structural change will inevitably affect the CSF circulation.3 Experimental SAH induced the lipid protein deposition of hippocampal CA1 area, and reduction of pyramidal cells. The former may be associated with cerebrospinal fluid running sluggish, resulting in hippocampal CA1 area cells metabolite transport disorders; the latter to consider the apoptosis accelerated caused by ischemia. These structural changes will affect the function of the hippocampus. |
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