THE ULTRASTRUCTURE OF MAUTHNER CELL SYNAPSES AND NODES IN GOLDFISH BRAINS

An electron microscope study of goldfish Mauthner cells is reported.¹ The cell is covered by a synaptic bed ~ 5 µ thick containing unusual amounts of extracellular matrix material in which synapses and clear glia processes are implanted. The preterminal synaptic neurites are closely invested by an interwoven layer of filament-containing satellite cell processes. The axoplasm of the club endings contains oriented mitochondria, neurofilaments, neurotubules, and relatively few synaptic vesicles. That of the boutons terminaux contains many unoriented mitochondria and is packed with synaptic vesicles and some glycogen but no neurofilaments or neurotubules. The bare axons of club endings are surrounded by a moderately abundant layer of matrix material. The synaptic membrane complex (SMC) in cross-section shows segments of closure of the synaptic cleft ~ 0.2 to 0.5 µ long. These alternate with desmosome-like regions of about the same length in which the gap widens to ~ 150 A and contains a condensed central stratum of dense material. Here, there are also accumulations of dense material in pre- and postsynaptic neuroplasm. The boutons show no such differentiation and the extracellular matrix is largely excluded around them. The axon cap is a dense neuropil of interwoven neural and glial elements free of myelin. It is covered by a closely packed layer of glia cells. The findings are interpreted as suggestive of electrical transmission in the club endings.     

THE TEETH OF HYPOGEOPHIS ROSTRATUS (AMPHIBIA, APODA) AND TOOTH STRUCTURE IN THE AMPHIBIA

The bipartite nature of the tooth has been recently used to demonstrate the close relationship between the three existing groups of Amphibia. However, Considerable doubt has remained as to the composition of the two parts of the tooth and the way in which they are linked.
It order to clearify the position the teeth in Hypogeophis were examined. It is clear that the bulk of the crown and the pedicel is composed of dentine which is produced by a continuous layer of odontoblasts. This layer of cells is also responsible for the formation of the fibrous ring which joins the two portions of the tooth. This ring is regarded as an area where the odontoblasts produce fibres and little or no matrix.     

人类活动对两栖动物群落结构的影响

本文报道了哀牢山徐家坝地区,山地水域环境植被的不同开发强度对两栖动物群落结构的影响。调查结果表明,水域环境植被未经破坏的原始常绿阔叶林生态类型其两栖动物群落结构由12种蛙组成,多样性指数2.41:原生植被曾被砍伐而演替为次生林生态类型由9种蛙组成,多样性指数1.97;原生植被曾遭受严重砍伐和火烧而演替为毛蕨草地和沼泽草甸生态类型,其两栖动物种数分别为6种和5种,多样性指数分别为0.70和0.57。由此可见森林植被破坏对两栖动物群落结构及动态都有决定性影响。     

METABOLIC CHANGES IN THE BRAINS OF MICE FROZEN IN LIQUID NITROGEN

Abstract— Autolytic changes in the mouse brain, occurring during immersion of the animal in liquid nitrogen, were evaluated by measuring the tissue concentrations of glucose, lactate, pyruvate, α-oxoglutarate, phosphocreatine, creatine, ATP, ADP and AMP. The values thus obtained were compared with those obtained in paralysed mice under nitrous oxide anaesthesia, the brains of which were frozen in such a way that arterial blood pressure and oxygénation were upheld during the freezing. Immersion of unanaesthetized mice in liquid nitrogen gave rise to significant alterations in phosphocreatine, creatine, lactate, lactate/pyruvate ratio, ADP and AMP. A comparison with values obtained in paralysed and anaesthetized mice that were frozen by immersion in liquid nitrogen showed that the metabolic changes observed in the unanaesthetized animals could not be caused by an anaesthetic effect on the metabolic pattern. It is concluded that autolysis in the mouse brain occurs during immersion of the animal in a coolant, mainly because arterial hypoxia develops before the tissue is frozen. A comparison with previous results on rat cerebral cortex indicates that mice offer no advantage for studies of cerebral metabolites in unanaesthetized animals. In both species, accurate analyses of labile cerebral metabolites require that the brain is frozen in a way that prevents arterial hypoxia during the fixation of the tissue.     

PLASMALOGENASE ACTIVITIES IN THE BRAINS OF JIMPY AND QUAKING MICE

The activity of plasmalogenase, which hydrolyzes the vinyl ether linkage of the plasmalogen molecule, increased markedly in control mouse brains during the period of most active myelin deposition. Only a slight increase in plasmalogenase activity was found in brains from jimpy mice. At all ages studied, the jimpy mouse brains had less plasmalogenase activity than the littermate control brains and this disparity increased with increasing age. By 25 days of age the jimpy brains contained only 43% of the activity observed in control brains. Adult quaking mouse brains also had significantly less plasmalogenase activity when compared to littermate controls. Thus, the plasmalogenase activities correlate well with the degree of myelination.     

THE ULTRASTRUCTURE OF THE ENAMEL IN THE GIANT PANDA OF PLEISTOCENE

<正> Enamel ultrastructures in the molar teeth of the giant panda, including Ailuropoda microta of the Early Pleistocene, Ailuropoda melanoleuca bacont of the Middle and Late Pleistocene and a living form, Ailuropoda rnelanoleuca, have been investigated by scanning electron microscopy. Transverse and longitudinal sections of enamel were made in order co evaluate shape, size and arrangement of the prisms. The sections were etched then with 0.074 M H_3PO_4 for 30-60 sec. Our investigations have shown certain features of the enamel which allow us to recognize differences among Ailuropoda on the basis of examination of large areas of the enamel. The results are summarized below.     

THE ULTRASTRUCTURE OF THE Z DISC IN SKELETAL MUSCLE

This electron microscopic study deals with the structure of the Z disc of frog's skeletal muscle, with special regard to the I filaments—whether they pass through the Z disc or terminate at it. In most longitudinal sections the I filaments terminate as rod-like projections on either side of the Z disc, one I filament on one side lying between two I filaments on the opposite side. This indicates that the I filaments are not continuous through the Z disc. The rod-like projections are often seen to consist of filaments (denoted as Z filaments) which meet at an angle. In cross-sections through the Z region the I filaments and Z filaments form tetragonal patterns. The I filaments are situated in the corners of the squares; the oblique Z filaments form the sides of squares. The tetragonal pattern formed by the Z filaments is rotated 45 degrees with respect to the tetragons formed by the I filaments on both sides of Z. This structural arrangement is interpreted to indicate that each I filament on one side of the Z disc faces the center of the space between four I filaments on the opposite side of Z and that the interconnection is formed by four Z filaments.     

梭鱼脑垂体超微结构

在梭鱼中,用电子显微镜能区别出6（或7）种形态的内分泌细胞类型。这些细胞与光学显微镜区分的6（或7）种细胞类型一致。促肾上腺激素分泌细胞和催乳素分泌细胞组成前-腺垂体;中-腺垂体由促性腺激素分泌细胞、促生长激素分泌细胞和促甲状腺激素分泌细胞组成;后-腺垂体包括M1、M2细胞。对每种细胞类型的超微结构特征作了详细描述,并与其他硬骨鱼的相应细胞作了比较讨论。不同的硬骨鱼,在超微结构方面每种细胞类型是一致的。       

THE DEVELOPMENT OF BEHAVIOUR IN ELEUTHERODACTYLUS MARTINICENSIS (AMPHIBIA, ANURA)

In the genus Eleutherodactylus , development is wholly embryonic. Among other features of ontogeny which are thereby modified is the development of behaviour. Within the egg envelope, the embryo is largely still, but wriggles from time to time. These movements represent all that remains of the axial swimming behaviour of larval Amphibia. The embryo develops normally when removed from the envelopes, and its reactions to light touch can then be studied from day to day. In E. martinicensis , which develops from first cleavage to hatching in 13-14 days, the first movement of the legs is seen during trunk wriggles at 7 1/2 days, but a day later they can move independently. The first reaction of the leg is a slow withdrawal; at 9 1/2 days flexion is followed by a vigorous extension. By then, reflexes affecting all four limbs can be elicited.
Towards the end of embryonic life, limb movements can be maintained in continuous cycles, and the animal can then swim. When it is allowed normally to emerge from the envolopes, the juvenile toad, smaller than a house fly, can jump a distance of over a foot. These observations are discussed in relation to the ontogeny of behaviour in other vertebrates, particularly in regard to the views of G. E. Coghill.     

THE ULTRASTRUCTURE OF THE M LINE IN SKELETAL MUSCLE

By electron microscopy, the ultrastructure of the M line was investigated in fibers from frog nonglycerinated semitendinosus muscles at body length and at different degrees of shortening and stretch. The M line appeared as a line of high electron opacity in the middle of the A band. Its framework consists of: (i) three (four or five) arrays of transverse M bridges, 200 A apart, connecting each A filament with its six neighbors; (ii) M filaments, parallel to the A filaments, passing through the M line and linking each set of M bridges together. In the shortened fiber the M line remained distinct. At high degrees of stretch, the M line became fainter or indiscernible. This appearance reflects a misalignment of the M components caused by a staggering of the A filaments. The M line reappeared after release of fibers stretched 70–80% above equilibrium length. On the basis of the structural analysis, the possible function of the M line is compared with that of the Z line, and a model is suggested for the M line.     

ULTRASTRUCTURE OF DNA-CONTAINING AREAS IN THE CHLOROPLAST OF CHLAMYDOMONAS

The chloroplast of Chlamydomonas moewusii was examined by electron microscopic and cytochemical methods for the possible presence of DNA. Both the Feulgen reaction and acridine orange indicated the presence within the chloroplast of one or more irregularly shaped DNA-containing bodies generally in the vicinity of the pyrenoid. Electron micrographs revealed 25 A microfibrils in these areas which correspond to DNA macromolecules with respect to their location, morphology, and sensitivity to deoxyribonuclease digestion. The possibility that this material is the genetic system of the chloroplast and the hypothesis that the chloroplast represents an evolved endosymbiont are discussed.     

神经毒性杀虫药剂对家蝇头部环腺苷酸含量的影响

本文报道用七类20种神经毒性杀虫药剂处理家蝇(Musca dcmestica vicina),发现引起环腺苷酸(cAMP)增加的药剂有:DDT、菊酯类和甲脒类,而BHC、狄氏剂、有机磷、氨基甲酸酯、沙蚕毒素均没有影响.并做了DDT、溴氰菊酯和杀虫脒中毒0—8小时内cAMP变化的时间曲线,以及DDT中毒0—8小时内腺苷酸环化酶(ACE)活性的时间曲线.结果表明:DDT中毒1小时引起cAMP达一峰值,2小时后回到原位;2—8小时内持续而缓慢的上升;乙酰胆碱酯酶活性曲线与此基本一致,但2—8小时内活性增加不大.溴氰菊酯中毒引起cAMP变化的时间曲线与DDT的基本一致,只是第二次cAMP上升更高二些.杀虫脒引起cAMP的时间变化曲线是0.5小时达一峰值,1小时基本回到原位,2—4小时有一个上升较快、较高的峰.我们认为,DDT引起cAMP值的第一次上升是激活了ACE造成的,第二次上升可能与钙调蛋白和磷酸二酯酶有关.杀虫脒引起cAMP值上升,是因为激活了章鱼胺激性的ACE.     

七星瓢虫精子鞭毛的超微结构(英文)

应用细胞整装制备和超薄切片技术,在透射电子显微镜下检查了七星瓢虫成熟精子鞭毛的超微结构。精子鞭毛是由一个典型的9＋9＋2轴丝,两个同形结晶的线粒体衍生物,两个附体（每个附体具有两部分,一个嗜锇致密月牙体和一个海绵月牙体）和一个非结晶体组成,在鞭毛终端部,仅存的轴丝失去了两个中央微管保留了9个具有动力蛋白臂的双微管和9个附微管。     

ULTRASTRUCTURE OF THE FLAGELLUM IN SPERM OF CKCINELLA SEPTEMPUNCTATA

Abstract  Using cell whole mount preparation and ultrathin section technique, the ultrastructure of the flagellum in the sperm of Coccinella septempunctata L. was examined with transmission electron microscope. The flagellum is made up of a classic 9+9+2 axoneme containing two similar crystallized mitochondria1 derivatives, two accessory bodies, which are divided in to two portions, an osmiophilic dense crescent and a spongy one, and a non-crystalline body. At the end of the flagellum, only the axoneme is present, it loses the two central microtubules but retains the nine doublets with dynein arms and the nine accessory microtubules.     

大白鼠第三脑室室管膜的超微结构

本文用扫描和透射电镜证实在成年大白鼠的第三脑室存在室管膜上神经元样细胞、神经胶质细胞和类组织细胞。神经纤维发自神经元样细胞或自脑室外穿入室腔而来,其末梢内含有清亮囊泡或兼有大颗粒囊泡。室腔內尚有膨大的树突末梢和室管膜细胞的球状小体。上述各种结构与感受、分泌和调节功能有关,并为下丘脑控制垂体机能的另一新途径(经脑脊液和室管膜)提供了形态学依据。     

猫丘脑腹后外侧核的超微结构

采用电镜技术观察了猫丘脑腹后外侧核的超微结构。该核内的神经元可分为大小两种类型，大型直径在１５—４０μｍ，小型小于１５μｍ，其胞质内容无明显差别。树突较多见，直径从１—１０μｍ不等。轴突可分为三种类型：含圆形小泡的小终末、终末及扁平小泡的终末。突触类型主要为轴树突触，此外还可见到轴体、轴轴、轴轴树、树树突触以及以树突为中心的突触复合体。在树突之间、树突与胞体之间还存在有非突触的丝状连接。