龙眼果皮微细结构的扫描电镜观察及其与果实耐贮性的关系

龙眼果实极不耐贮藏，采后极易失水、褐变和腐烂。无包装的福眼龙眼在(10±1)℃、50%RH下贮藏1d，果实失重5.84%，果皮失水13.59%，果皮开始褐变；贮藏2 d时果实失重10.37%，果皮失水26.40%，大部分果皮发生褐变；果皮褐变与果实失重、果皮失水都呈极显著正相关(P＜0.01)；果实失水主要发生在果皮而不是果。0.015 mm厚的聚乙烯薄膜袋密封包装可极显著(P＜0.01)地减少果实失重和果皮褐变。用扫描电镜观察龙眼果皮结构，发现其果皮由外果皮、中果皮和内果皮组成。外果皮周皮层薄；外果皮表面栓质少，未形成连续的栓质层；外果皮表面有许多相互连接的微裂口和形状、大小不同的皮孔；中果皮细胞间隙多、空隙大；皮孔通道与中果皮细胞间隙相通。龙眼果蒂部由维管束、石细胞和通气组织组成，具有大的细胞间隙和胞间腔。这些显微结构易引起采后果实失水、果皮褐变和病原微生物侵染，从而导致果实耐藏性和抗病性差。讨论了龙眼外果皮表面主色为褐色和内果皮比外果皮更容易褐变的解剖学原因及龙眼果皮结构与果实保鲜的关系。     

四季鹅产蛋前后腺垂体远侧部细胞的超微结构比较

对处于产蛋、停产和产前等不同时期的四季鹅腺垂体远侧部分泌促激素的６类细胞,即促生长激素细胞（α细胞）、催乳激素细胞（η细胞）、促卵泡形成激素细胞（β细胞）、促黄体生成激素细胞（γ细胞）、促甲状腺激素细胞（δ细胞）及嫌色细胞等的超微结构作了比较观察。结果表明,产蛋期嗜碱性β、γ和δ细胞呈旺盛的细胞结构象,细胞器结构发达,腺体功能活跃;停产期特征是η细胞稍增多,细胞器少,腺体功能处于相对静止;产前期仅α细胞功能活跃,嫌色细胞数量较多,此时腺体功能低下。     

早熟和正常中华绒螯蟹大颚器官发育及超微结构

对早熟和正常发育的中华绒螯蟹(Eriocheirsinensis)大颚器官(mandibularorgan,MO)进行解剖学和组织学研究,发现早熟蟹的MO在当年秋季已充分发育,MO细胞直径在当年11月达到最大值;而正常发育幼蟹的MO在当年细胞排列紧密,直到翌年秋季才充分发育。正常发育成蟹(二秋龄蟹)的MO细胞直径在10月达到最大值,明显大于早熟蟹(P<0.05)。表明早熟蟹MO较正常发育蟹提早一年发育,但是,秋季早熟蟹MO的发育速度和发育良好程度均不及二秋龄蟹MO的发育,这可能是早熟蟹卵黄发生过程较缓慢,较二秋龄蟹滞后约一个月达到次级卵黄发生末期的原因。中华绒螯蟹MO细胞超微结构的显著特征是丰富而形态多样的光面内质网和具小管状内嵴的线粒体,以及丰富的游离核糖体。     

林芝牦牛毛绒纤维物理特性及其超微结构研究

对 5岁林芝牦牛 2 0头公牛和 2 5头母牛背、腹部毛绒纤维的物理特性及其超微结构进行了测定与观察。结果表明 :公、母牛背、腹部粗毛的伸直长度分别为 8.82± 3.40、2 3 .2 3± 8.2 0、5 .6 2± 1.19、18.95± 4.84cm ,母牛腹部绒毛的伸直长度为 4.74± 0 .72cm ;公、母牛背、腹部粗毛的细度分别为 5 2 .99± 10 .72、73.32± 7.2 0、5 4.6 3± 10 .0 2、6 5 .96± 6 78μm ,母牛腹部绒毛的细度为 17.35± 2 .2 2 μm ;公、母牛背、腹部粗毛的强度分别为 41.16± 9 32、38.82± 3 .2 8、31 19± 7.87、33 .88± 5 .84g ,母牛腹部绒毛的强度为 15 .2 8± 2 .96g ;公、母牛背、腹部粗毛的伸度分别为 41.84%、46 73%、41.2 1%、45 .76 % ,母牛腹部绒毛的伸度为 43 .91%。林芝牦牛粗毛和绒毛的鳞片排列形态均为覆瓦状形     

CaCl2浸泡处理对银杏贮藏品质和种壳超微结构的影响

以银杏核用主栽品种佛指和龙眼为试材,将其种核用1% CaCl2浸泡处理24 h,然后置于室温下贮藏,研究在贮藏过程中种核呼吸强度和品质变化规律,并对种壳超微结构进行观察.结果表明:①银杏种核单粒重和种仁呼吸强度、含水量、总淀粉含量及支链淀粉含量均随贮藏时间的延长而下降,浮籽率则呈上升趋势;品种间比较以龙眼呼吸强度高、水分散失快、营养消耗高;CaCl2处理后种核的水分散失和养分消耗均受到抑制,种仁呼吸强度也有下降,其中龙眼的处理效果较为明显.②银杏种壳由大量管胞组成,管胞表面光滑,穿孔明显,穿孔主要有圆形和撕裂状;管胞直径和穿孔的形状、分布、大小品种间差异显著,与佛指比较龙眼的管胞直径较小、穿孔面积较大;CaCl2处理后种壳表面密布钙质颗粒,部分颗粒覆盖于管胞的穿孔洞口,减少了水分的散失和O2的进入,提高了银杏种核贮藏性能.     

向日葵锈菌单核和双核吸器的超微结构比较研究

观察发现,向日葵锈菌单核吸器和双核吸器存在一系列的差异:(1)单核吸器母细胞隔膜不产生隔膜突,入侵口四周的吸器母细胞壁不局部增厚;(2)单核吸器母细胞在入侵寄主细胞壁时不形成入侵栓;(3)双核吸器由管状的颈部和膨大的吸器体组成,单核吸器呈菌丝状;(4)在双核吸器形成过程中,寄主细胞可分泌胼胝质和产生与侵染有关的管状结构。结果表明向日葵锈菌单核的吸器母细胞和吸器的特异性明显低于双核的吸器母细胞和吸器。     

鹅肾超微结构的研究

应用组织切片和透射电子显微镜技术，研究了２５只成年鹅肾脏的显微和超微结构。结果表明，近曲小管有发育良好的刷状缘；远曲小管有特征性的指状突起，中间夹有大而长的线粒体；肾小球毛细血管围绕间膜细胞呈圆周形排布；肾小囊足细胞的突起与毛细血和内皮及基膜紧密相贴，三者构成肾小球的滤过屏障。     

培植羊黄的扫描电镜观察

对培植羊黄进行了扫描电镜观察,并与培植牛黄,天然牛黄进行比较。三种黄的超微结构相似,分层明显,都具有丝网状结构,黄的基质部分为硫酸化多糖粘蛋白所构成。     

Transmission electron microscopy for characterization of acrosomal damage after Percoll gradient centrifugation of cryopreserved bovine spermatozoa

The objective of this study was to characterize acrosomal ultrastructure following discontinuous Percoll gradient centrifugation of cryopreserved bovine sperm. Semen was collected from six bulls of different breeds and three ejaculates per bull were evaluated. Frozen semen samples were thawed and the acrosomal region of sperm cells was evaluated by transmission electron microscopy (TEM) before (n = 18) and after (n = 18) Percoll centrifugation. The evaluation of 20 sperm heads from each of the 36 samples analyzed ensured that a large number of cells were investigated. The data were subjected to analysis of variance at a level of significance of 5%. Percoll centrifugation reduced the percentage of sperm exhibiting normal acrosomes (from 61.77 to 30.24%), reduced the percentage of sperm presenting atypical acrosome reactions (from 28.38 to 4.84%) and increased the percentage of sperm exhibiting damage in the acrosome (from 6.14 to 64.26%). The percentage of sperm with typical acrosome reactions was not significantly different before (3.70%) and after (0.67%) centrifugation. TEM distinguished four different types of acrosomal status and enabled ultrastructural characterization of acrosomal injuries. The percentage of sperm exhibiting normal acrosomes decreased and damage in the acrosome was the most frequent acrosomal injury with the Percoll gradient centrifugation protocol utilized.     

Cellular and ultrastructural changes in the seedling roots of upland rice (Oryza sativa) under the stress of two allelochemicals from Ageratina adenophora

Two sesquiterpene‐derivative compounds, 4,7‐dimethyl‐1‐(propan?2‐ylidene)–1,4,4a,8a‐tetrahydronaphthalene‐2,6(1H, 7H)‐dione (DTD) and 6‐hydroxy‐5‐isopropyl‐3,8‐dimethyl?4a,5,6,7,8,8a‐hexahydronaphthalen‐2(1H)–one (HHO), are the major putative allelochemicals of the aqueous leachates of Ageratina adenophora. A laboratory experiment was conducted, using the hydroponic method, to evaluate the cellular and ultrastructural changes in the seedling roots of upland rice under the stress of DTD and HHO. The subsequent changes were observed in the treated upland rice roots in comparison with their controls. The scanning electron microscopy results showed that the DTD‐treated root tip cells turned into an irregular arrangement and shape and that most of them were wizened, with a poor cytoplasm. In the HHO treatment, the root tips had many irregularly shaped cells, with a greater number of sloughing cells, as well as short, wide cells that resulted in spherical and wider, but shorter, roots. At the ultrastructural level, DTD and HHO induced irregularly shaped and lobed nuclei, increased cytoplasmic vacuolation, reduced ribosome density and dictyosomes, and a reduced number of mitochondria in the cells, which indicated limited protein transportation and a reduced capability to export substances for cell development and growth in the upland rice seedling roots. The overall effect of HHO on the upland rice seedlings was more pronounced than that of DTD.