脊椎动物松果器官的形态结构比较和演化初探

对脊椎动物６个纲中日本七鳃鳗、鲫鱼、黑斑蛙、丽斑麻蜥、家鸽和高原鼠兔等几种动物松果器官的形态结构进行了观察和比较,并对其演化作了初步探讨。脊椎动物的松果器官分为二大类,一类为变温动物的松果器官,由副松果体和松果体构成,其中副松果体是一个典型的光感受器,松果体亦主要具有感光的结构。另一类为恒温动物的松果器官,仅包含松果体,无副松果体,其结构主要具有内分泌腺的特征。在系统演化中,后一类松果器官可能是由前一类演变来的。从演化揭示：最早脊椎动物的松果眼是２个。哺乳动物的松果腺是由一种光感受器演变来的。     

鲫鱼松果体的显微和超微结构研究

本文作者发现鲫鱼的松果体与一般硬骨鱼不同,它除由背囊和背囊内褶中松果管所组成的松果体外,还有退化的旁突体和副松果体.背囊是单层柱状纤毛上皮,其腔与第3脑室相通,松果管由光感觉细胞、支持细胞、节细胞、丰富的血管和无髓神经纤维构成.松果体既是光感受器又有内分泌的功能.       

高寒草甸生态系统中高原鼠兔和高原鼢鼠的捕食风险及生存对策

调查青藏高原高寒草甸生态系统中两种主要啮齿动物及其天敌动物的种群密度,分析天敌动物对两种啮齿类的捕食方式、捕食强度,探讨啮齿类动物的捕食风险及生存对策。研究结果表明,高原鼠兔和高原鼢鼠的种群密度分别为4．97只／hm^2和10．6只／hm^2,而它们的主要天敌赤狐、艾虎和香鼬的种群密度分别为0．16只／100hm^2、0．37只／100hm^2、3只／100hm^2。艾虎和香鼬在取食过程中主要搜寻啮齿类的洞道系统,全部食物几乎都来源于洞道系统内;赤狐或取食地面活动的鼠兔,或挖掘洞口待高原鼢鼠封闭洞口时取食猎物。高原鼠兔在赤狐、艾虎和香鼬的食物中所出现的频次分别为100％、96．1％、100％,高原鼢鼠在3种天敌动物的食物中所出现的频次分别为87．5％、73．2％、0％。3种天敌动物对高原鼠兔和高原鼢鼠的捕食强度分别为0．703％和0．038％,高原鼠兔和高原鼢鼠所承受的捕食风险分别为0．780和0．393。高原鼠兔在高的捕食风险下通过行为对策和繁殖对策增加其适合度,而承受捕食风险较小的高原鼢鼠主要通过封闭的洞道系统和高的存活率增加其适合度。     

松果体对“生物钟”的调节

松果体对“生物钟”的调节刘开乾（江西省永新县涅田中学３４３４０６）松果体是由原始脊椎动物的松果眼发展而来的一种内分泌腺体。腺体外有结缔组织被膜包着,被膜还伸人腺实质中,把腺实质分隔成不规则的小叶。腺实质里由松果体细胞和神经胶质细胞构成,神经胶质细胞围...     

血管活性物质对大鼠低氧性肺血管结构重建作用的研究

目的：探讨内皮素-1（ET-1）、血管内皮生长因子（VEGF）在低氧性肺血管结构重建中的调节作用。方法：将2260m处的Wistar大鼠带到3417m的高度饲养24h,2周、3周后进行实验并和在当地捕捉到的高原鼠兔进行比较。取血,测定血液中的ET-1、VEGF的含量,然后取肺组织固定切片染色,40倍光镜下计数整个切片内的肺泡水平位上直径小于100μm的肌性动脉（AM）、部分肌性动脉（PAM）和非肌性动脉（NMA）的数目,分别计算它们各占肺小血管总数的百分比。左右心室室间隔分别称重．计算右室／左室＋室间隔。结果：高原鼠兔与缺氧不同时间大鼠VEGF及ET-1经组间方差分析均有显著差异（P〈0．01,随着缺氧时间的延长,大鼠MA及PMA的比例增加,NMA减少,RV／LV＋S逐渐增加（和高原鼠免比P〈0．01）,经组间方差分析亦有显著差异（P〈0．01）。结论：低氧环境下VEGF及ET-1共同参与了肺小血管的肌化过程,在低氧性肺动脉高压的发生发展中起到了重要作用,但在高原鼠兔体内仅具有维持组织器官发育和维持其正常功能的作用。     

羊松果体细胞原代培养及其生物学特性的研究

体外培养山羊及绵羊的松果体细胞,观察其增殖情况和功能状态的变化.结果显示:山羊、绵羊的松果体细胞体外形态及生长情况相似.细胞多呈圆形或多角形,细胞体积有增大趋势.采用MTT法检测细胞生长状态,发现细胞有明显的增殖现象,大约于11d达到高峰.用免疫组织化学对培养细胞进行染色,发现5-HT阳性细胞数量随细胞的增殖而增加.表明山羊和绵羊松果体细胞在体外均增殖旺盛,并能保持体内的分泌功能.     

高原鼠兔和昆明白小鼠肺组织结构比较

低氧性肺血管收缩反应钝化（blunted Hypoxic Pulmonary Vasoconstriction, bHPV）是高原鼠兔在进化过程中形成的对低氧环境的一种适应性策略。以胎儿期、幼龄期及成年期高原鼠兔和昆明白小鼠为研究对象,对两者的肺组织进行发育生物学、比较组织学和比较组织化学研究,以探讨高原鼠兔bHPV形成的组织形态学基础。结果表明：（1）高原鼠兔各时期肺组织微血管的双层弹性纤维含量均低于25%,无明显肌化现象;（2）高原鼠兔直径10~50 μm、50~100 μm和100~200 μm微血管的中膜肌层厚度与其外径比（MT/ED）随年龄增加而逐渐下降;成年高原鼠兔的肺组织微血管MT/ED10-50显著低于成年昆明白小鼠（P < 0.05）,但MT/ED50-100和MT/ED100-200均无明显的种间差异（P > 0.05）;（3）在直径10~50 μm直径范围微血管中,高原鼠兔和昆明白小鼠平滑肌细胞数与内皮细胞数的比值（SMC/EC）均随年龄增长呈上升趋势,且高原鼠兔SMC/EC的比值极显著低于同年龄组的昆明白小鼠（P < 0.01）。导致高原鼠兔bHPV发生的组织学基础可能是其肺组织中直径10~50μm微血管平滑肌细胞数量少。     

高原低氧对高原鼠兔和大白鼠肺泡Ⅱ型细胞及表面活性物质超微结构的影响

本文报道高原低氧(海拔3300米)对高原鼠兔、移居高原大鼠、急进高原大鼠的肺泡Ⅱ型细胞及表面活性物质超微结构的影响。发现高原鼠兔肺占体重的百分比低于移居高原大鼠(P>0.05)和急进高原大鼠(P<0.001)。透射电镜和扫描电镜观察,表明急进高原大鼠肺泡Ⅱ型细胞微绒毛减少,线粒体变性肿胀,板层体排空、合成减少。而高原鼠兔未出现上述超微结构改变。移居高原大鼠的微细结构变化介乎于高原鼠兔与急进高原大鼠之间。     

高原鼠兔诱导型一氧化氮合酶cDNA克隆及序列分析

高原鼠兔Ochotona curzoniae,世居在青藏高原海拔3000~5000 m的地区,是一种典型的低氧耐受哺乳动物。一氧化氮(NO)作为一种有效的血管舒张因子,在预防低氧诱导的低氧性肺血管收缩反应和肺动脉高压中发挥着重要功能。诱导型一氧化氮合酶(iNOS)是一种催化L-精氨酸合成NO的重要酶,受低氧调控。本研究经RTPCR和cDNA 3’末端快速扩增(3’RACE)方法成功克隆了高原鼠兔iNOS基因cDNA序列,并对其分子特征进行了分析。结果显示:高原鼠兔iNOS cDNA全长为3981 bp,开放阅读框(ORF)为3450 bp,共编码1149个氨基酸残基;预测的蛋白序列与北美鼠兔、兔、人、大鼠、小鼠、狗以及猪的同源性分别为98%、87%、82%、78%、78%、82%和83%;蛋白结构预测结果显示高原鼠兔iNOS具有氧化域、还原域及黄素腺苷酸结合区域等iNOS所具有的典型结构域;基于iNOS的最大似然树和贝叶斯树均支持鼠兔与兔有最近的亲缘关系,与形态或其他分子标记构建的进化关系相符;分子进化分析检测到高原鼠兔iNOS中存在3个正选择位点——32T、33Y和46R,但不同模型的结果表明哺乳动物iNOS基因所受选择以净化选择为主,不支持iNOS在高原鼠兔支系发生适应性进化。该研究为揭示高原鼠兔iNOS的表达特征及其在低氧适应中的作用与调控机制研究奠定了初步基础。     

高原鼠兔褐色脂肪组织及肝脏产热的季节性变化

非颤抖性产热(nonshtverlng thermogenesis, NST)是小哺乳动物在低温环境下增加产热的有效途径(Foster等1978.Can JPhyslol,56:110~122)。NST主要产生于褐色脂肪组织(BAT),所有影响BAT结构与功能的因素均可影响NST能力(Cannon等,1993．Life in the cold．369～379)。 高原鼠兔(Ochotona curzoniae)为高寒草甸生态系统中非冬眠的小哺乳类动物,其生态学特征已被进行了广游酊探^的研究．王德华等(1990。兽类学报10(1)：40～53; 1993．兽类学报13(4)：271～276)对高原鼠兔NST能力,BAT组织成分及线粒体蛋白的季节性变化进行了研究。本文在此工作的基础上。试图从细胞承千上进一步探讨高原鼠兔产热的季节性变化及适应意义。     

蒙古黄鼠（Citellus dauricus）松果腺的超微结构观察

The distal part of pineal gland of the Mongolian ground squirrel was ultrastructurally studied. The gland was composed of low electron-dense parenchymal cells, among which glial cells, pigment cells, blood vessels and neural elements were occasionally interspersed. The pinealocytes contained numerous mitochondria, lysosomes, microtubules, microfilaments, Golgi apparatus and free ribosomes, as well as less prominent profiles of rough- and smooth-surfaced endoplasmic reticula and some cilia, centrioles, synaptic ribbons and few subsurface cisterns. Some pinealocytes were vacuolated. The content of the vacuoles released into the extracellular space by exocytosis could be observed. The gap junctions between pinealocytes were also observed. Of particular interest was that many mitochondria "fused together" and formed gap junction-like structure in about five percent pinealocytes. The pigment cell has a amorphous nucleus which contains many aggregated chromatin, its cell membrane has a few microvilli projecting into a central lumen, these features may indicated that this kind of cell differs either from the pinealocyte or astrocyte. There are axo-axonic synapses or axo-dendritic synapses between neuron processes or between neuron processes and pinealocytes.     

蒙古黄鼠(Citellus dauricus)松果腺的超微结构观察

蒙古黄鼠松果腺主要由低电子密度的松果腺细胞和少量的胶质细胞、含色素细胞、神经突起及血管等组成。松果腺细胞内含有大量的线粒体、溶酶体、微丝、高尔基器、游离核糖体及中等量的光面和粗面内质网。纤毛、中心粒、突触带和致密芯小泡很少。松果腺细胞之间及胶质细胞之间存在电突触。最新被观察到的是大约有5%松果腺细胞内的线粒体产生“融合”现象,形成类似电突触的结构。神经突起可形成轴—轴突触,轴—树突触,并与松果腺细胞形成突触。     

Morphologic evidence of photoreceptor differentiation of pinealocytes in the neonatal rat

The pineal body and the retina of the neonatal Sprague-Dawley rat were studied by light and electron microscopy, and the morphologic differentiation of the parenchymal cells of the pineal body was compared with that of the developing photoreceptor cells of the retina. Between the ages of 4 and 12 days after birth, some of the developing pinealocytes were observed to become elongated and polarized, with their nuclei located at one pole. "Synaptic" ribbons were observed within the cell body. At the opposite pole the cells developed elongated cell processes that initially contained microtubules and ribosomes. These cell processes projected into luminal spaces and were attached by structures resembling zonulae adherentes to the adjacent cells. Extending from the tips of the cell processes, cilia with a 9 + 0 arrangement were observed. Lamellated and vesicular membranes were noted at the tips of the cilia. Such morphologic differentiation, however, could be observed only in rats younger than 17 days. Comparison of the morphologic features of the neonatal pinealocytes with those of the developing retinal photoreceptor cells showed much similarity. It is suggested that the pinealocytes of the neonatal rat undergo "photoreceptor-like" differentiation during a transient neonatal period. Such morphologic differentiation may provide an explanation for light-induced biochemical changes described in neonatal rats whose eyes had been enucleated.     

Effect of photoperiod on pineal gland volume and pinealocyte size in the Chinese hamster, Cricetulus griseus

Male adult (200-day-old) Chinese hamsters (Cricetulus griseus) raised from weaning under either LD 16:8 or LD 8:16 were used. The pineal gland of the Chinese hamster consists of superficial (major) and deep (minor) components and a continuous, or interrupted, narrow parenchymal stalk interposed between them. The volume of the superficial pineal including the parenchymal stalk is greater under LD 16:8 than under LD 8:16. Under both photoperiods, pinealocytes in the superficial pineal have larger nuclei and more abundant cytoplasm than those in the deep pineal. Nuclei in the superficial pineal appear pale and usually have irregular profiles, whereas those in the deep pineal appear dark and have round profiles. In the superficial pineal, pinealocyte nuclei are larger, paler, and more irregular; and, in addition, nuclear density is lower under LD 16:8 than under LD 8:16. Similar, but less prominent, photoperiod-induced changes occur in the volume of the deep pineal, the size of pinealocytes, and pinealocyte nuclear morphology in the deep pineal. The results indicate that the development and differentiation of pinealocytes in both pineal portions may be advanced under long photoperiods and delayed under short photoperiods, although pinealocytes in the deep pineal may remain not fully differentiated even in adults. Since testicular weights and body weights are similar under both photoperiods, the photoperiod may exert marked influences on the development of the pineal gland without affecting reproductive activity and growth rates of animals.     

A histochemical study of aldehyde fuchsin-positive material and "high-esterase cells" in the pineal gland of the Mongolian gerbil.

The pineal gland of the Mongolian gerbil consists of a superficial gland, stalk and deep pineal. The deep pineal differentiates postnatally. Histochemical studies of the superficial pineal gland indicate that it may be involved in the secretion of protein. Presumptive secretory material visualized by aldehyde fuchsin (AF) and chrome hematoxylin was observed along the course of blood vessels and among the pinealocytes. The distribution and texture of the AF-positive material was distinctive. It did not correspond to the pattern and texture of material stained with PAS, Sudan Black or acid orcein. Staining with AF was markedly reduced after incubation with trypsin, indicating that the AF-positive material is at least partially protein. The amount of stainable material increased with age. The AF-positive material was observed in what appeared to be interstitial or glial cells and processes, and in the processes of perivascular cells. Cells and fibrous processes with high non-specific esterase activity ("high-esterase cells") were observed among the pinealocytes and along the course of blood vessels. The distribution of the "high-esterase cells" and the morphology and texture of their esterase-containing processes were remarkably similar to the morphology and distribution of the material that stained with AF. It may be that the "high-esterase cells" contain AF-positive material. The "high-esterase cells" hydrolyzed both alpha-naphthyl acetate and alpha-naphthyl butyrate. The pinealocytes hydrolyzed only alpha-naphthyl acetate. The "high-esterase cells" appear to form a distinct class of cells within the superficial pineal gland. They are tentatively identified as a type of glial cell.     

"Light" and "dark" pinealocytes of the porcine pineal gland

Both qualitative and quantitative comparative studies of "dark" and "light" pinealocytes of the porcine pineal gland have been carried out. These cells differ from each other in their electronic density of cytoplasm, shape of nucleus, the structure of membrane bound dense bodies and the number of microtubules and smooth endoplasmic reticulum. The membrane bound dense bodies--characteristic structures of pig pinealocytes as well dense core vesicles occur in both types of cells. The relative volume of the majority of the cells' organellae apart from the Golgi apparatus, also do not show any significant difference. The results obtained support a functional basis for pinealocyte differentiation in the porcine pineal gland.     

Morphometric analysis of the pineal complex of the golden hamster over a 24-hour light:dark cycle: II. The deep pineal in untreated and optically enucleated animals

The deep pineal gland of golden hamsters was morphometrically analyzed and quantitatively compared with the superficial pineal under a 14:10 lighting regime and following blinding. The deep pineal comprised 6-10% of the total pineal parenchymal tissue. Pinealocytes of the deep gland were smaller than the cells of the superficial pineal and showed a greater percent volume of Golgi bodies, rough endoplasmic reticulum, and dense-cored vesicles. Twenty-four-hour rhythms in nucleoli and Golgi bodies were found in deep pinealocytes. These rhythms were out of phase with comparable rhythms in the superficial pineal gland, suggesting that distinct subpopulations of pinealocytes are present within the respective parts. Blinding resulted in decreased nuclear and nucleolar volume, while the amount of smooth endoplasmic reticulum, Golgi bodies, dense bodies, and dense-cored vesicles increased significantly. Marginal increases were seen in mitochondria and lipid droplets. The greater abundance of those organelles involved in synthesis and secretion suggests enhanced cellular activity after blinding. Many of the morphological responses are similar to alterations in the pinealocytes of the superficial pineal following optic enucleation.     

Fine-structural study of the pineal body of the monkey (Macaca fuscata) with special reference to synaptic formations

Summary Various types of synaptic formations on pinealocytes and pineal neurons were found in the pineal body of Macaca fuscata. Axo-somatic synapses of the Gray type-II category were detected on the pinealocyte cell body. Gap junctions and ribbon synapses were observed between adjacent pinealocytes. About 70 nerve-cell bodies were detected in one half of the whole pineal body bisected midsagittally. They were localized exclusively deep in the central part. When examined electron-microscopically, they were found to receive ribbon-synapse-like contacts from pinealocytic processes. They also received synaptic contacts of the Gray type-I category on their dendrites, and those of the Gray type-II category on their cell bodies from nerve terminals of unknown origin. All these synapse-forming axon terminals contained small clear vesicles. Thus, the pineal neurons of the monkey, at least in part, are suggested to be derived from the pineal ganglion cells in the lower vertebrates and not from the postganglionic parasympathetic neurons. The functional significance of these observations is discussed in relation to the innervation of the pineal body of the monkey.     

The pineal gland of the gerbil,Meriones unguiculatus

Summary Electron microscopy was employed in a study of the pineal gland of the Mongolian gerbil (Meriones unguiculatus). It was determined that the gerbil pineal gland contains pinealocytes and glial cells with the pinealocytes being the predominant cell type. The pinealocytes contain numerous organelles traditionally considered as being either synthetic or secretory in function such as an extensive Golgi region, smooth (SER) and rough (RER) endoplasmic reticulum, secretory vesicles and microtubules. Other cytoplasmic components are also present in the pinealocytes (synaptic ribbons, subsurface cisternae) for which no function has been assigned. Dense-cored vesicles are rare. Vacuolated pinealocytes are present and appear to be intimately associated with the formation of the pineal concertions. Evidence presented supports the proposal that the concretions form within the vacuoles. Once the concretions reach an enlarged state, the vacuolated pinealocytes break down and the concretions are thus extruded into the extracellular space where they apparently continue to increase in size. The morphology of the glial cells was interpreted as indicative of a high synthetic activity. The glial cells contain predominantly the rough variety of endoplasmic reticulum and form an expansion around the wide perivascular area.Supported by NSF grant PCM 77-05734     

Prenatal development of "synaptic" ribbons in the guinea pig pineal gland

Pineal "synaptic" ribbons are a heterogeneous population of organelles. "Synaptic" ribbons (SR) sensu stricto, "synaptic" spherules (SS), and intermediate forms (IMF) are present. Their function and origin are unknown, and a knowledge of their prenatal development is lacking. Thus the pineal glands of prenatal, neonatal, and adult guinea pigs were prepared for electron microscopy. "Synaptic" ribbons were studied morphologically and quantitatively. The three categories of "synaptic" ribbons reported in adult pineal glands were also present in prenatal pineal glands. Their structural features, distribution, grouping, and composition patterns are similar to those in adults. "Synaptic" ribbons were first detected in pinealocytes of the distal region of a 42-day postcoitus (PC) pineal gland and were comparable with those in adults. They increased in number with age and reached a peak at 63 days PC, followed by a steep decline at 66 and 67 days PC. By day 69 PC, the numbers increased again and showed a dramatic increase after birth. Several true ribbon synapses were seen at day 63 PC between pinealocyte cell processes or between pinealocyte cell process and pinealocyte cell body. Since true ribbon synapses have not been found in adult guinea pig pinealocytes, their synaptic nature could have been lost during development. No precursors for the "synaptic" ribbons were found. The endoplasmic reticulum cisternae may be the origin for the ribbon vesicles because of their close association with the "synaptic" ribbons.