Testis Development and Ultrastructural Features During Spermatogenesis in Cultured Small Yellow Croaker,Larimichthys polyactis

The small yellow croaker Larimichthys polyactis is an economically important marine fish in Northeast Asia.Currently,its natural resources are threatened by overfishing and environmental pollution.Therefore,research on the reproductive system of the fish is crucial.Here,we studied the testis development and ultrastructural features of spermatogenesis in cultured L.polyactis using anatomical,histological,and ultrastructural techniques.A pair of testes,consisting of a central sperm duct and radial seminiferous lobules,were observed.The reproduction cycle of testes can be divided into stages I–VI.March to May was confirmed as the breeding season for male L.polyactis,while April is the ideal period for artificial breeding.The male L.polyactis can attain sexual maturity within 1 year.The spermatogenesis of L.polyactis comprised spermatogonium,spermatocyte,spermatid,and mature spermatozoon.The morphology of spermatogenic cells changed obviously during spermiogenesis,including nuclear shaping,midpiece and flagellum formation.The mature sperms consist of an ellipsoidal head,a short midpiece,and a long flagellum.The anterior of the head with a kidney-shaped nucleus can be distinguished.The midpiece is located posterior to the head and includes four to six spherical mitochondria.The flagellum has irregular lateral fins.The testis of L.polyactis is an unrestricted lobular type,with cystic spermatogenesis,type II spermiogenesis,and type II spermatozoa.These features are highly similar to those of other Sciaenid species.Our findings provide useful insights into the mechanism underlying testis development and spermatogenesis of L.polyactis,which can facilitate the artificial breeding of this species.

ULTRASTRUCTURAL OBSERVATIONS ON SPOROGENESIS OF MYXOBOLUS KWANGSIENSIS HSIEH, GONG & XIAO FROM THE KIDNEY OF DACE LABEO ROHITA

The early stages and capsulogenetic stages of sporogenesis of Myxobolus kwangsiensis were studied indetail by electron microscopy. M. kwangsiensis is an intrasellular myxsporen infecting the epithelial cellsof kidney tubules of young dace Labeo rohita. The M. kwangsiensis sporogenesis presents the typical featuresof myxosporea. The initial stages are multinuceate primary cells, with one primary cell typicallyenclosing one secondary cell. The secondary cells are formed directly by cytokinesis inside the primary cells. Theprimary cell participates in the formation of the secondary cell nucleus. The nuclear division of primarycell is asynchronous by amitosis. The parasitic organisms may degenerate inside the epithelial cells at anystage. The modes of sporoblast formation , the typical features of myxosporea and the cause of its degradationare discussed.

Ultrastructural Pathologic Observation on the Gut-Associated Lymphoid Tissues of Sacculus Rotundus of Rabbits Infected with Rabbit Haemorrhagic Disease Virus

Ultrastructural pathological changes in the gut-associated lymphoid tissues of sacculus rotundus (SR) of rabbits infected with rabbit haemorrhagic disease virus (RHDV) were first observed. There were numerous holes at the luminal and basement membrane surfaces of the dome epithelium (DE), consistently accompanied by necrosis of lymphocytes and M-cells, and pronounced depletion of lymphocytes in the domes and follicles, decrease of DE complex with formation of pseudomembranous structure on the surface of the dome epithelium. A specific finding in lymphocytes and macrophages was that severe destruction detraction of the membrane of rough endoplasmic reticulum(RER) was accompanied by conspicious increase of solitary, ribo-some-like particles in the cytoplasm, with appearances of intranuclear particles and intranuclear inclusions. It was found that there were many round and dense virion-like particles, with 26 nm in diameter, in the nuclei and cytoplasm of lymphoctes, plasma cells, macrophages and fibroblasts, or in degenerated cells and cellular debris. At the same time, another round virion-like particles about 34 nm in diameter were also seen in the cytoplasm of some cells and interstitium. The results indicated that the appearances of the ribosome-like particles, virion-like particles and inclusion bodies were related to the replication and assembly of RHDV. The present observations suggested that DE of sacculus rotundus could be a open pathway and a transporting route for the entry of antigens into hosts. While the antigen is profoundly deleterious, DE may be as a closed portal or a barrier preventing the foreign antigenic materials from invading.

Ultrastructural Pathology of Nerve Cells in Mouse Brain Infected with Epidemic B Encephalitis Virus

An animal model of epidemic(Japanese)B encephalitis was estabilisged by injecting theJin Wei Yah 1 stain of B encephalitis virus into the peritoneal cavity of mice.The ultrastructuralchanges of the nerve cells in their brains were studied,special attention being paid to some types ofnerve cell in the cerebellar cortex.The infectet Purkinje cells and especially the granular cells showedspecial and inter,sting pathological features.These were compared with the changes found in the in-fected nerve cells in the cerebral cortex,diencephalon and mesencephalon.A radiating structure consisting of a microveside-microtubule aggregation body at the centerand endoplastic reticulum or virus replication multivesicular structures around it was often found in thein fected nerve cells.Its morphological features were described in detail,and its significance and the se-quenoe of events of its development discussed.In the late stage of infection,virus particles were found in the nuclei of part of the necroticcells.It is considered that they entered the nuclei from the cytoplasm during or after the death of theinfected cells.The observation smade in this study have comfimed in the granular cell of the cerebellum theidea of Chert et al.that the encephalitis B virus particle can he formed in the perinudear cistem ofthe infected nerve cell,and have brought forth further information in this respect.The way of releaseof the virus particles from the infected nerve cells observed in this study is fundamentally consistentwith that observed by Chen et al.but most of the virus particles left the nerve cell via the cell pro-

Clinical, cellular, microscopic, and ultrastructural studies of a case of fibrogenesis imperfecta ossium

Fibrogenesis imperfecta ossium is a rare disorder of bone usually characterized by marked osteopenia and associated with variable osteoporosis and osteosclerosis, changing over time. Histological examination shows that newly formed collagen is abnormal, lacking birefringence when examined by polarized light. The case presented demonstrates these features and, in addition, a previously undocumented finding of a persistent marked reduction of the serum C3 and C4. Osteoblasts established in culture from a bone biopsy showed abnormal morphology on electron microscopy and increased proliferation when cultured with benzoylbenzoyl-ATP and 1,25-dihydroxyvitamin D, contrasting with findings in normal osteoblasts in culture. A gene microarray study showed marked upregulation of the messenger RNA(mRNA) for G-protein-coupled receptor 128(GPR 128), an orphan receptor of unknown function and also of osteoprotegerin in the patient's osteoblasts in culture. When normal osteoblasts were cultured with the patient's serum, there was marked upregulation of the mRNA for aquaporin 1. A single pathogenetic factor to account for the features of this disorder has not been defined, but the unique findings described here may facilitate more definitive investigation of the abnormal bone cell function.

DISTRIBUTION AND ULTRASTRUCTURAL LOCALIZATION OF CARCINOEMBRYONIC ANTIGEN (CEA) IN SIGNET RING CELLS OF GASTRIC CANCER

The distribution and ultrastructural localization of CEA in signet-ring cells of 15 gastric cancer specimens were observed by PAP and immunoelectron microscopic methods. The mechanism of abnormal distribution of CEA in the signet-ring cell and its biological significance are discussed. The results showed that the CEA positive rate in signet-ring cells was 100% with the polarity lost in distribution. Under the light microscope, the CEA stain patterns were of two types: cytoplasmic and membranous types. The former was predominant. Under the electron microscope, most of the CEA was distributed on the cell membrane and cytoplasm. CEA was found in intracellular membranous structure of the cancer cells, especially in protein synthesis and transport organellae (RER, Golgi Complex etc.). The synthesis of CEA in cancer cells increased, yet its elimination was somewhat hampered. The result was that the RER became extended and were full of CEA (+) material. In the free signet-ring cell, there was a small and short contact plane. The tight junction was severed as the cell junction reduced. The antigenic determinant of CEA was glycoprotein. The abnormal distribution of CEA in signet-ring cells might be the morphologic reflection of the glycosylation of surface glycoprotein of tumor cells.

A CLINICAL AND ULTRASTRUCTURAL STUDY OF ACUTE ESOINOPHILIC LEUKEMIA

The present study analyses two cases with acute immature eosinophilic leukemia. The clinical, physical, laboratory and pathologic materials are discussed. There is an abnormal number of immature eosinophilic cells in the blood and bone marrow, usually accompanied by anemia and thrombocytopenia. Especially the ultra-structural features include abnormal granules, asynchronous maturation of the nucleus and cytoplasm, dilated endoplasmic reticulum and more conspicuous nucleoli. Differential count was more precise under electron microscope than under light microscope. These findings may be helpful for differential diagnosis and classification.

ULTRASTRUCTURAL CHARACTERISTICS OF NEPHROBLASTOMAS AND THEIR RELATION TO DNA PLOID

Fifty-one cases of nephroblastoma were pathologically studied by light and electron microscopy as well as microspectrophotometry. Under light and electron microscope, the tumor appeared to be carcinosarcoma structurally, consisting of epithelial, sarcomatous and undlfferentiated tumor cells. Their ultrastructural feature was similar to that of renal tubular epithelial cells and tibroblast. It could differentially be diagnosed from renal metoblastic tumors by electron microscopy when the tumor was mainly composed of sarcomatous cells. Microspectrophotometer measurement showed an Increased mean nuclear DNA content (DI>1. 04), belonging to aneuplold tumor, which together with polyploid cells, serving as one of the Important characteristics of malignant tumors. In addition, the poorer the tumor differentiation the higher was the DNA content of the tumor cells, suggesting that the measurement of nuclear DNA of tumor cells might also serve as one of signs to acertain the degree of differentiation and malignant of nephroblastomas with more preciseneas than general morphological examinations.

Enzymatic and Ultrastructural Studies in a Freshwater Catfish: Impact of Methyl Parathion

Exposure to a sublethal concentration of methyl parathion (MEP) reduced the activity of cytoplasmic malate dehydrogenase. mitochondrial malate dehydrogenase, and lactate dehydrogenase by 30 to 49% in the liver and the skeletal muscle of the freshwater catfish, Clarias batraclms, after 7 days. The activities then began to recover and reached the control levels on the 28th day of MEP exposure. A complete recovery occurred on the 7th day when MEP was withdrawn from the medium after an exposure for 1 week. The withdrawal-dependent recovery in the activities was inhibited partially or completely by actinomycin Dandcycloheximide, suggesting de nova synthesis of the enzymes during the recovery period. A conjoint treatment of MEP and triiodolhyronine (T_3) restored the activities to control levels, indicating T_3 protection against the pesticide toxicity. SDS-PAGE of the cytoplasmic fraction of the liver showed some noticeable changes in the protein pattern after an exposure to MEP. Ultrastructural studies on MEP-treated liver cells showed disappearance of the glycogen granules and appearance of numerous smooth endoplasmic reticulum, lysosomal dense bodies, and swollen mitochondria. These changes in the liver are an indication of hepatic toxicity leading toward necrosis.(c) 1990 Academic Press.Inc.

Ultrastructural Observations of The Anterior Chamber Angle Tissues in Congenital Glaucoma

Eighteen trabeculectomy specimens of congenital glaucoma were examined by light and transimssion electron microscopy. The results showed that the primary anomalies in congenital glaucoma included the developmental defects of trabecular meshwork, excessive collagen fibrils in the trabecular matrix, shifting forward of ciliary muscle fibres and persistent mesenchymal tissues in the anterior-chamber angle. The authors also pointed out the importance of the secondary lesions of the trabecular meshwork in th...

Ultrastructural Alterations in Testes from Rats Treated with Cysteine

Cysteinc administration in relatively large doses has been repetitively employed as preventive agent against chemically induced cell injury or as radioprotector. In this work we report that administration of a dose standard for those purposes (1.9gr/kg, po in water) causes significant ultrastructurally evident alterations in testcs at 24h. Damage involves Scrtoli cells and spermatids. Alterations found in the former include dilatation of nuclear membrane and of the smooth (SER) and rough endoplasmic reliculum (RER) and detachment of ribosomes from RER. Cytoplasm appeared more sparse and electron lucent than in controls and contained more lipid droplets and lysosomcs. Mitochondria exhibited alterations in shape and size.Damage in spermatids consisted of the appearance of irregular shape of the nucleus and alterations in their acrosomal caps. There was no histochemical evidence for either calcium accumulation or lipid peroxidation occurrence in testes of cysteine-trcated animals. Results indicate that the large doses of cysteine employed in prevention of radiation or chemical effects is able to cause injury to Sertoli cells of the testes. Damage observed does not reach irreversible stages but may be sufficient to lead to production of abnormal spermatids.

ULTRASTRUCTURAL STUDY ON THE INVASION OF RETINAL INNER LIMITING MEMBRANE BY THE MALIGNANT TUMOR CELLS

To observe the process of invasion, retina of rat was used as a model to substitute the inner limiting membrane of retina for the basement membrane. Retina invaded by esophageal carcinoma cells and B16 melanoma cells upon the inner limiting membrane was studied by scanning and transmission electron microscopy. The results showed that the inner limiting membrane was destroyed by both kinds of tumor cells. The process of destruction was followed by a series of transformations in the inner limiting membrane, i.e. folding, swelling, thickening, and granular change. The inner limiting membrane was dissolved focally as a result of transformation, and then tumor cells invaded the retina through these dissolved regions. It seems that, as a barrier, the inner limiting membrane plays a similar role as the basement membrane.

Cardiac functional and ultrastructural changes in early diabetic cardiomyopathy rabbits

Objectives It is not fully clarified how diabetes mellitus induced cardiac dysfunction and myocardial ultrastructural changes in the early state.In the present study,we provided an integrated approach to investigate early changes in myocardial function of diabetic rabbits and assessed the structural alteration.Methods and Results Diabetes was induced by alloxan injection.After 30 days,echocardio- graphy and left ventricular cannulation were performed in dia- betic(D,n=8) and control rabbits(C,n= 10).After catheterization, animals were killed for histological studies.Hema-toxylin -eosin and Masson’s Trichrome staining of the heart were analyzed.The ultrastructure of left ventricle was also examined with electron microscopy.Echocardiography revealed that early diabetic cardiomyopathy had impaired LV diastolic function expressed by diminished E-waves,increased Awaves, E/A ratio reversion and increased E-wave deceleration time(EDT).Concurrently,LV end-diastolic pressure(LVEDP) and diastolic time constant(T) were increased,minimum dP/ dt(LV-dp/dt)was reduced,obtained through cardiac catheterization.There were no significant differences in LV ejection fraction(EF),LV peak systolic pressure(LVSP), or maximum dP/dt(LV + dp/dt).Qualitative light microscopy revealed no histologic changes in myocardium from diabetic rabbits.The most evident ultrastructural change was spotted myofibrillar damage,while interstitial fibrosis was slight.Conclusions These results suggest that early diabetic cardiomyopathy in animal model is characterized by left ventricular diastolic dysfunction,both impaired active relaxation and increased passive chamber stiffness.Whereas,left ventricular systolic function can remain normal.It might partly contribute to myofibrillar damage,but not myocardial fibrosis.

Dynamic and ultrastructural study of sphincter of Oddi in early-stage cholelithiasis in rabbits with hypercholesterolemia

AIM To study the relationship between pre-formation of gallstone and the kinetics and ultra-structure of sphincter of Oddi.METHODS Adult female rabbits were used anddivided into 3 groups,and fed with either normalor high cholesterol diet for four or eight weeks.Each group contained eight rabbits.Themanometry of sphincter of Oddi,biliarycineradiography,gallbladder volumemeasurement and ultrastructure observationunder electron microscope were performed.RESULTS In groups Ⅰ and Ⅱ,the basalpressure in low-pressure ampulla or highpressure zone of sphincter of Oddi waselevated,the amplitude of phasic contractionwas decreased and the volume of gallbladderwere increased,with a significant difference(P【0.01)from those of control.Gallstones werefound in group Ⅱ rabbits(7/8).Undercineradiography,low-pressure ampulla showeda spasmodic status without apparent peristalticcontraction.Under electron microscope,insidethe muscular cells of sphincter of Oddi,loosening of microfilament and swelling ofplasmosomes which congregated at the top wereobserved.The amount showed no obviouschange under nitric oxide synthase(NOS)stain.CONCLUSION Twisting of the microfilamentand disarrangement of kink macula densa insidethe muscular ceils suggested that the sphincterof Oddi was under spasmodic status.Theimpaired diastolic function caused andaggravated the stasis of cystic bile.Theswelling plasmosome could be one of theimportant factors in elevating the tonic pressureof sphincter of Oddi.

Lipid Peroxidation and Ultrastructural Modifications in Brain after Perinatal Exposure to Lead and/or Cadmium in Rat Pups

Objective To assess lipid peroxidation and ultrastructural modifications in rat brains following perinatal exposure to lead （Pb） and/or cadmium （Cd）. Methods Female rats were divided into four groups： control group, Pb （300 mg/L） group, Cd group （10 mg/L） and Pb＋Cd （300 mg/L, 10 mg/L） group. The compounds were delivered in the drinking water throughout pregnancy and lactation. Results The levels of compounds in blood and brain of the Pb＋Cd group were similar to those of other groups, but the effects of Pb＋Cd on pups＇ body and brain weights were higher than on other compounds. Electron microscopy revealed that Pb and Cd had effects on mitochondrial swelling, disruption and cristae loss, Nissl body dissolution, degenerated organelles and vacuoles, cytomembrane disappearance, and nuclear chromoplasm concentration. The activity of glutathione peroxidase （GSH-Px）, superoxide dismutase （SOD）, catalase （CAT）, acetylcholinesterase （ACHE） was decreased, whereas the activity of maleic dialdehyde （MDA） was increased. Conclusion Perinatal exposure to low doses of Pb and Cd can produce alterations in lipid peroxidation and ultrastructural modifications in rat brains, and exposure to both metals can result in greater damages.

Reduction of Chilling Injury and Ultrastructural Damage in Cherry Tomato Fruits After Hot Water Treatment

The effects of hot water treatment in alleviating chilling injury and reducing ultrastructural damage of mature-green cherry tomatoes （Lycopersicun esculentum cv. cerasiform Alef） were investigated. Mature-green cherry tomato fruits were treated in water at 40℃ or 45℃ for 5 min or 15 min, and then stored at 5℃ for 19 days followed by ripening at 20℃. Water treatment at 40℃ for 15 min increased tolerance of cherry tomato fruits to chilling stress, indicating as low outbreak of skin lesion, high color a＊ value, and low electrolyte leakage. Treated fruits showed typical climacteric respiration and developed normal red color with chlorophyll degradation and lycopene accumulation during ripening, while fruits without treatment failed to develop red color and suffered skin lesion. After 19 days of chilling, heated fruits showed the conversion of chloroplast to chromoplast with the disappearance of thylakoids. Mitochondria and other cell organelles were not adversely affected in treated fruits. However, ultrastructures in pericarp cells in control fruits severely damaged with extensive disorganization of cytoplasm, swelled chloroplasts, distorted and unstacked thylakoids. Chloroplast was the first and most severely impacted organelle by chilling stress. Hot water treatment （40℃ for 15 min） before storage alleviated chilling injury in cherry tomato fruits. The results suggest that chilling injury is related with the damage of cell structure under chilling stress.

Ultrastructural changes in the optic nerve and capillary vessels during early stages of optic nerve injury

BACKGROUND： Capillaries are the only blood supply for optic nerves, which makes the system more vulnerable to impaired blood circulation. OBJECTIVE： To observe the ultrastructural changes in the optic nerves and capillaries in rabbits following intracanalicular segment injury to the optic nerve. DESIGN, TIME AND SETTING： Comparative, observational, pathological morphology was performed at the Department of Anatomy, Weifang Medical College from September to November 2007. MATERIALS： Models of intracanalicular segment injury to the optic nerve were induced in the right eye of thirty healthy, adult rabbits by a free-falling metal cylinder. The H-7500 transmission electron microscope was provided by Hitachi, Japan. METHODS： All rabbits were randomly assigned into experimental （n = 25） and control （n = 5） groups. Optic nerve specimens were obtained from the experimental group at 0.5, 6, 12, 48, and 96 hours, respectively, following injury. Ultrastructural changes to the optic nerves and their capillaries were observed by electron microscopy. Optic nerve injury was not established in the control group, but optic nerve specimens were collected similarly to the experimental group. MAIN OUTCOME MEASURES： Ultrastructural changes in the injured optic nerves and their capillaries. RESULTS： Thirty rabbits were included in the final analysis. In the control group, cross-sections of the optic nerves exhibited varied thicknesses with regularly arranged fibers. The axons appeared to be smooth with condensed myelin sheaths and oval mitochondria. The microtubules and microfilaments were clearly seen. The lumens of the capillaries were regular with densely arranged endothelial cells and visible mitochondria. In the experimental group, 30 minutes after injury to the optic nerves, swollen axons, sparse myelin sheath, disordered microtubules and microfilaments, swollen mitochondria, and a decreased number of pinocytosis vesicles and microfilaments in endothelial cells of the capillaries were observed. At 6 hours, medullary and vacuolar degeneration in the mitochondria, and swollen endothelial cells in the capillary, were visible. At 12 hours, these changes were more obvious. At 48 hours, granular dissolution of microtubules, microfilaments, and mitochondria, as well as diffuse degeneration of mitochondria in the endothelial cells, were observed. At 96 hours, axonal disintegration, vacuolar degeneration, and dilated capillaries were observed. CONCLUSION： During early stages, the injured intracanalicular optic nerve exhibited swollen axons with vacuolar degeneration, swollen and degenerated mitochondria, decreased number of microtubules and microfilaments, and dilated capillaries with increased permeability.

Ultrastructural and G-6-Pase Cytochemical Studies of Injurious Action of Cadmium and Protection of Zinc on Rat Leydig Cells

Objective To investigate ultrastructural effects of cadmium(Cd) and zinc(Zn) on rat Leydig cells (LCs) and the possible mechanisms of Cd induced injury. Methods The Wistar rats were injected with low dose cadmium chloride (CdCl 2, 2 mg/kg body weight).The specimens obtained from 1 h to 60 d after dosing were studied by using transmission electron microscope (TEM) combined with a quantitative analysis of glucose 6 phosphatase(G 6 Pase) cytochemistry. Meanwhile, the protective effects of Zn on Cd induced injury were observed. Results The ultrastructural changes of LCs were detected at 4 h after Cd treatment and became more serious after 24 h. The main alterations were dilatation of smooth endoplasmic reticulum (SER), increasing of lipid droplets and myelin figures as well as appearing of vacuoles in the endothelial cell of lymphatic and blood capillaries. At 3,7 and 15 d, the degeneration above mentioned was most prominent, numerous necrotic LCs and flocculent densities in mitochondria were observed. After 30 d, the injuries of LCs appeared to be alleviated. But most of LCs still not recovered to normal after 60 d. However, the G 6 Pase reaction products was found to be reduced at 1 h after Cd treatment, and such decrease was most pronounced within 3～15 d. After 30 d, there was an obviously recovery of the G 6 Pase reaction product. The injuries of LCs of Zn protected groups were gentle and the G 6 Pase reaction products were more than that of Cd treated groups at the same time. Conclusions The early injuries of LCs were related to the direct action of Cd; the effects of Cd on the G 6 Pase activities occured earlier than the morphological alterations; the damage of lymphatic and blood capillaries as well as interstitial fibrosis might accelerate the degeneration and Zn could protect obviously LCs from damage by Cd.

Ultrastructural observation of liver tissue ablation induced by high-intensity focused ultrasound

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Ultrastructural changes of rat cortical neurons following ligustrazine intervention for cerebral ischemia/reperfusion injury

BACKGROUND： Ligustrazine can reduce the production of free radicals and the content of malonaldehyde, and improve the enzymatic activity of adenosine-triphosphate in cerebral anoxia. It also can increase the expression of heat shock protein-70 and Bcl-2, thus alleviating brain tissue injury caused by cerebral ischemia/reperfusion. This study aimed to address the question of whether ligustrazine can protect the membrane structure of neurons. OBJECTIVE： To establish rat models of cerebral ischemia/reperfusion, observe the membrane structure and main organelles of neurons with electron microscope after ligustrazine intervention, and to analyze the dose-dependent effects of ligustrazine on neuronal changes. DESIGN： A randomized controlled study. SETTING： Department of Anatomy Research and Electron Microscopy, Hebei North University. MATERIALS： Forty Wistar rats of SPS grade, weighing 180-250 g and equal proportion of female and male, were provided by Hebei Medical University Animal Center （No. 060126）. The ligustrazine injection （40 g/L, No. 05012） was produced by Beijing Yongkang Yaoye. LKB4 Ultramicrotome was purchased from LKB Company in Sweden. JEM100CXII electron microscope was purchased from JEOL in Japan. METHODS： The experiment was performed in the Laboratory of the Department of Anatomy and Electron Microscopy, Hebei North University from June to August 2006. （1） Wistar rats were allowed to adapt for 3 days, and were then randomly divided into four groups, according to the numeration table method： normal group, model group, low-dose ligustrazine group, and high-dose ligustrazine group. There were 10 rats in each group. （2）Rats in the model group, low-dose ligustrazine group, and high-dose ligustrazine group underwent cerebral ischemia/reperfusion model, according to Bannister＇s method. The carotid artery was opened for reperfusion after 90 minutes of cerebral ischemia. Samples were collected from the cerebral cortex after 24 hours. Animals from the ligustrazine low-dose group and ligustrazine high-dose group received ligustrazine injections, 50 mg/kg and 100 mg/kg, respectively. Samples were collected at the same time as the model group. MAIN OUTCOME MEASURES： Alterations of the neuronal ultrastructure and main organelles were observed by electron microscopy. RESULTS： Forty Wistar rats were included in the final analysis. Plentiful ribosome and rough endoplasmic reticulum existed in the cytoplasm of cortical neurons in the normal group. Edema existed in the nucleus and cytoplasm of neurons in the model group. The cell membrane was damaged, resulting in the external eruption of certain cellular organelles. In the low-dose ligustrazine group, neuronal swelling was decreased in the cytoplasm, whereas cellular organelles were relatively increased. However, the mitochondria remained swollen. The double layer structure disappeared in parts of the mitochondrial membrane. The caryotheca was still broken, and neuronal damage was significantly decreased in the high-dose ligustrazine group. In addition, cytoplasmic swelling was reduced andmost part of caryotheca was complete. Fragmentation of the cellular membrane was not detected. Mitochondrial cristae and the lysosome could also be detected. The number of rough endoplasmic reticulum and free ribosomes was increased, and the structure of great part of caryotheca was clear. In addition, the number of nuclear pore was increased. However, the nuclear heterochromatin was relatively reduced. CONCLUSION： In the rat, the protective effects of ligustrazine were significant on neuronal membrane structures and main organelles after cerebral ischemia/reperfusion. There was a dose-dependent effect between neuronal changes and Ligustrazine.