Ultrastructure of the dorsal claustrum in cat. II. Synaptic organization

The claustrum is a bilateral subcortical nucleus situated between the insular cortex and the striatum in the brain of all mammals. It consists of two embryologically distinct subdivisions - dorsal and ventral claustrum. The claustrum has high connectivity with various areas of the cortex, subcortical and allocortical structures. It has long been suggested that the various claustral connections have different types of synaptic contacts at the claustral neurons. However, to the best of our knowledge, the literature data on the ultrastructural organization of the different types of synaptic contacts in the dorsal claustrum are very few. Therefore, the aim of our study was to observe and describe the synaptic organization of the dorsal claustrum in the cat. We used a total of 10 adult male cats and conducted an ultrastructural study under a transmission electron microscope as per established protocol. We described a multitude of dendritic spines, which were subdivided into two types - with and without foot processes. Based on the size and shape of the terminal boutons, the quantity and distribution of vesicles and the characteristic features of the active synaptic zone, we described six types of synaptic boutons, most of which formed asymmetrical synaptic contacts. Furthermore, we reported the presence of axo-dendritic, axo-somatic, dendro-dendritic and axo-axonal synapses. The former two likely represent the morphological substrate of the corticoclaustral pathway, while the remaining two types have the ultrastructural features of inhibitory synapses, likely forming a local inhibitory circuit in the claustrum. In conclusion, the present study shares new information about the neuropil of the claustrum and proposes a systematic classification of the types of synaptic boutons and contacts observed in the dorsal claustrum of the cat, thus supporting its key and complex role as a structure integrating various information within the brain.     

Basement membranes in the kidney of the dromedary camel (Camelus dromedarius): An immunohistochemical and ultrastructural study

Basement membranes consist of various proteins, the major ones being laminin and collagen type IV. Primary defects in these two proteins have been extensively associated with kidney pathologies. This study aimed to establish baseline information on the immunohistochemical distribution of laminin and collagen type IV, and to corelate these with the ultrastructure of basal laminae in the uriniferous tubules of the dromedary camel. Tissue samples were taken from the kidneys of eight adult female camels, and processed for immunohistochemical and ultrastructural investigations. Strong intensity of collagen type IV was observed within the basement membranes of Bowman’s capsule. The thickness of the basal lamina of the parietal layer of Bowman's capsule varied extensively depending on the region of the renal corpuscle; the thicker areas were always associated with cuboidal epithelial cells. The glomerular basement membrane revealed strong immunostaining of laminin, whereas the mesangial matrix was strongly immunoreactive to collagen type IV. Abundant amount of laminin was found in the basement membranes of proximal convoluted tubules, thin limbs of the loop of Henle, and collecting ducts. Dense immunostainings of laminin and collagen type IV were observed in the medullary regions of uriniferous tubule, in which numerous projections extended from the basal laminae into the subjacent connective tissue. Overall, the present study revealed marked variations in the distribution of the basement membrane markers laminin and collagen type IV in the uriniferous tubules of camel kidney. The results have also shown difference in the thickness of basal laminae. This variation in thickness, however, was unlikely to be influenced by the amount of laminin and collagen type IV.     

The influence of 30-day-old Streptococcus mutans biofilm on the surface of esthetic restorative materials--an in vitro study

OBJECTIVE: To evaluate the effects of Streptococcus mutans biofilm/restorative materials interaction on surface roughness, hardness and morphology of materials tested. METHODS: Empress 2 (E2), Filtek Supreme (FS), Vitremer (V) and Ketac Molar Easymix (KM) were tested. Twenty-five disks of each material were made and divided into three storage groups: (1) 100% relative humidity (n=5); (2) growth medium (BHI and 1% sucrose) (n=5); (3) S. mutans biofilm-growth medium (n=15). Before storage, hardness measurements were immediately obtained from group 1 specimens. After 30 days of storage, the specimens were cleaned in order to obtain the surface roughness and hardness values, besides morphology analysis by scanning electron microscopy. RESULTS: The surface roughness and hardness values obtained from E2 and FS specimens did not present statistically significant differences among the groups 1, 2 and 3 and between immediate and 30-day-old specimens of each material. However, group 3 specimens of V and KM showed statistically significant higher surface roughness means than other groups. Group 1 specimens of V and KM also showed higher hardness values than the immediate values. Group 3 specimens of V presented decreased hardness values compared with other groups. The scanning electron micrographs showed an increase in surface degradation from group 1 to group 3 for FS, V and KM. CONCLUSIONS: Thirty-day-old biofilm promotes a negative effect on the surface morphology of FS, V and KM, on the surface roughness of V and KM and on the hardness of V.     

牙体预备对牙龈结合上皮损伤后的超微结构观察

目的 :研究烤瓷修复体牙体预备对牙龈结合上皮损伤后 ,牙龈结合上皮在透射电镜下形态学变化的特点。方法 :将 16只家兔的 3 2颗上前牙分别用金刚砂车针和手术刀破坏左侧上前牙的牙龈结合上皮 (JE) ,以右侧同名牙为对照 ,分别于 1、2周取材 ,利用透射电镜观察结合上皮的组织学改变 ,并对 2实验组进行对比观察。结果 :金刚砂车针处理组和手术刀处理组 2周后牙龈结合上皮附着恢复 ,两处理组无明显差别 ,与未经手术处理的JE比较 ,处理组主要超微结构变化是线粒体空泡化 ,基膜不完整。结论 :牙体预备对牙龈结合上皮的损伤 ,可导致结合上皮的超微结构改变     

茶多酚对+Gz过载的颞下颌关节影响分析

目的：观察茶多酚对持续性高正加速度（＋Gz）加载颞下颌关节的影响。方法：雄性Wistar大鼠随机分成5个不同处理条件的实验组，每组12只。A组为空白对照。B组地面固定5min。C 固定于离心机转臂上，俯卧位，头向轴向，＋Gz离心5min。D组体位同C组，＋10Gz离心30s，间隔时＋1Gz离心60s，连续每天5次，每周4天，共3周，E组实验参数同D组，并于＋Gz离心前1h灌胃给予茶多酚（200mg.kg^-1)，其余各组给予等量蒸馏水，通过光镜，扫描和透射电镜观察比较组颞下颌关节的组织形态学变化情况，结果：A、B、C三组颞下颌关节未见异常；D组颞下颌关节表面凝胶状物质缺失，胶原纤维断裂，成纤维细胞线粒体变性；E组颞下颌关节表面凝胶状物质变薄但完整，胶原纤维断裂，成纤维细胞线粒体较正常，结论：茶多酚能在一定程度上保护凝胶状物质和成纤维细胞来对抗持续性高正加速度对颞下颌关节的损伤。     

细菌胞外膜泡的电镜观察

本实验对分离的５株细菌的ＥＣＶ作了电镜观察，证实４株菌都能形成ＥＣＶ，但在量上有差异。以ＰｇＷ５０最为典型，菌体及其ＥＣＶ的结构层次清晰可见；ＰｅＥＣＶ的荚膜层较薄且直径相对小而均一；Ｐｍ和Ｐｉ的ＥＣＶ大小不均一，标本中破裂现象和不规碎片出现较早。     

Hardness,elasticity and ultrastructure of primary tooth dentin bonded with a self-reinforcing one-step self-etch adhesive

Objective

This study evaluated the interfacial quality of sound and caries-affected primary tooth dentin bonded with a self-reinforcing one-step self-etch adhesive.

Methods

Non-carious, sound dentin was prepared with water-cooled high-speed diamond burs. Caries-infected dentin was removed with water-cooled low-speed round steel burs and hand instrument. Dentin was bonded with Bond Force (Tokuyama Dental). A nano-indentation tester was employed for determination of hardness (H) and Young's modulus (Y) of resin–dentin interface. Similar resin–dentin interfaces were examined with a SEM/EDX, and with a TEM using ammoniacal silver nitrate tracer for nanoleakage.

Results

In the comparison of the H and Y values between the interfacial dentin and the underlying mineralized dentin, no significant difference was seen in caries-affected dentin, however, the values of the interfacial dentin were significantly lower in sound dentin. The H value of the interfacial dentin of sound dentin was significantly lower than that of caries-affected dentin with significantly higher Ca content. No significant difference was observed in the Y values of the interfacial dentin of the two substrates. For both sound and caries-affected dentin, TEM revealed silver deposits in the interfacial dentin and adhesive layer, and smear layer remained within the resin–dentin interface. However, Ca and P contents of the adhesive layer at 10 μm above the dentin surface were the same as those present in the interfacial dentin.

Conclusions

Both for sound teeth and caries teeth, Bond Force does not prevent the nanoleakage along the resin–dentin interface.     

Study on the effects of mechanical pressure to the ultrastructure and secretion ability of mandibular condylar chondrocytes

During mandibular movement, condyle is subjected to repetitive compression and the mandibular condylar chondrocytes (MCCs) can detect and respond to this biomechanical environment by altering their metabolism. The present study was undertaken to investigate the effects of pressure to the ultrastructure, aggrecan synthesis, nitric oxide (NO) and prostaglandin F(1)alpha(PGF(1)alpha) secretion in MCCs. In vitro cultured rabbit MCCs were incubated and pressed under continuous pressure of 90kPa for 60min and 360min by hydraulic pressure controlled cellular strain unit. The ultrastructure, aggrecan mRNA expression, activity of nitric oxide synthase (NOS) and PGF(1)alpha secretion were investigated. Besides, nitric oxide inhibitor was used together with pressure to investigate the role of NO in mechanical effects. The appearance of MCC on TEM showed that after been pressed under 90kPa for 60min, the cellular processes became elongated and voluminous, together with aggrecan mRNA increasing. Under 90kPa for 360min, some of the cells showed distinct sign of apotosis and the aggrecan mRNA decreased. Pressure of 90kPa could cause increase of NOS activity and decrease of PGF(1)alpha composition. Inhibitor experiments indicated that pressure-induced upregulation of aggrecan mRNA and inhibition of PGF(1)alpha synthesis was partly mediated by NO. Continuous pressure could cause changes on the ultrastructure and function of MCC, as well as up-regulation of aggrecan synthesis, increase of NO secretion and decrease of PGF(1)alpha composition. NO was the upstream molecule, which mediated the response of aggrecan and PGF(1)alpha to mechanical pressure.     

5种哺乳动物和人涎腺组织学及超微结构观察

目的研究5种动物涎腺组织形态学及超微结构特点.方法选用成年小型猪5只,猕猴2只,新西兰白兔7只、Wistar大鼠7只和昆明小鼠7只及人类正常腮腺和颌下腺组织各一例,行腮腺和颌下腺组织学、组织化学及超微结构观察.结果5种动物的腮腺组织学表现差异不明显,均为浆液性腺体.5种动物的颌下腺组织学差异较大,人、小型猪、猕猴颌下腺均为混合性腺体,而大、小鼠和兔颌下腺为浆粘液性腺体.组化染色结果表明形态相似的腺泡细胞,其合成产物不尽相同.5种动物腮腺和颌下腺腺泡细胞在超微结构方面除分泌颗粒表现出明显的差异外,其余结构差异不明显.结论在小型猪、猕猴、兔、大鼠和小鼠5种动物的涎腺组织学及超微结构上,猕猴和小型猪与人类最接近.     

高流体静力压和缺氧对大隐静脉和脾静脉滋养血管超微结构的影响

目的观察大隐静脉和脾静脉滋养血管内皮细胞超微结构变化,探讨高流体静力压和缺氧对滋养血管内皮细胞的影响。方法收集曲张大隐静脉和高压性脾静脉管壁标本34例,另设对照组为正常大隐静脉和脾静脉34例。采用HE染色光镜下观察大隐静脉和脾静脉外膜层滋养血管,半薄切片定位。再采用超薄切片,透射电镜下观察滋养血管内皮细胞的超微结构变化。结果大隐静脉曲张组和病脾静脉组滋养血管内皮细胞细胞核结构完整,染色质分布正常;部分线粒体基质深染,嵴模糊、嵴断裂。结论高流体静力压和缺氧下大隐静脉和脾静脉管壁滋养血管内皮细胞的超微结构会出现重塑现象,二者改变相同。