Cellular architecture of the lamina propria of human seminiferous tubules

Summary The lamina propria of human seminiferous tubules is composed of 5 to 7 cellular layers separated by laminae of extracellular connective-tissue components. By means of immunocytochemical methods the different nature of the cellular layers could be defined for the first time. Based on the light-microscopic demonstration of both desmin-like and vimentin-like immunoreactivity in the inner 3 to 4 layers of the lamina propria, these cells can be identified as myofibroblasts. The outermost one or two cellular layers, on the contrary, only show a vimentin-like immunoreactivity indicating the pure fibroblastic nature of these cells. Therefore, the outermost cellular layers are suggested to be derivatives of the interstitium. In cases of disturbed spermatogenesis, the lamina propria is frequently considerably thickened by an increase in the extracellular matrix components between the cellular layers. Whereas the ultrastructural localization of laminin-, collagen type-IV- and fibronectin-like immunoreactivity remains unaffected in the thickened lamina propria, the desmin-like immunoreactive cells of the inner layers strongly decrease in number and staining intensity. Most probably, the myofibro-blasts lose their myoid characteristics to participate in the secretion of increased amounts of extracellular matrix components, which in turn presumably block the mediation of the lamina propria between the interstitium and the germinal epithelium. It is still unclear whether the thickened lamina propria provokes the disturbance of spermatogenesis or vice versa.     

Interneuronal and glial-neuronal gap junctions in the lamina ganglionaris of the compound eye of the housefly,Musca domestics

Summary The cell-body layer of the lamina ganglionaris of the housefly, Musca domestica, contains the perikarya of five types of monopolar interneuron (L1–L5) along with their enveloping neuroglia (Strausfeld 1971). We confirm previous reports (Trujillo-Cenóz 1965; Boschek 1971) that monopolar cell bodies in the lamina form three structural classes: Class I, Class II, and midget monopolar cells. Class-I cells (L1 and L2) have large (8–15 m) often crescentshaped cell bodies, much perinuclear cytoplasm and deep glial invaginations. Class-II cells (L3 and L4) have smaller perikarya (4–8 m) with little perinuclear cytoplasm and no glial invaginations. The midget monopolar cell (L5) resides at the base of the cell-body layer and has a cubshaped cell body. Though embedded within a reticulum of satellite glia, the L1–L4 monopolar perikarya and their immediately proximal neurites frequently appose each other directly. Typical arthropod (-type) gap junctions are routinely observed at these interfaces. These junctions can span up to 0.8 m with an intercellular space of 2–4 nm. The surrounding nonspecialized interspace is 12–20 nm. Freezefracture replicas of monopolar appositions confirm the presence of -type gap junctions, i.e., circular plaques (0.15–0.7 m diam.) of large (10–15 nm) E-face particles. Gap junctions are present between Class I somata and their proximal neurites, between Class I and Class II somata and proximal neurites, and between Class II somata. Intercartridge coupling may exist between such monopolar somata. The cell body and proximal neurite of L5 were not examined. We also find that Class I and Class II somata are extensively linked to their satellite glia via gap junctions. The gap width and nonjunctional interspace between neuron and glia are the same as those found between neurons. The particular arrangement and morphology of lamina monopolar neurons suggest that coupling or low resistance pathways between functionally distinct neurons and between neuron and glia are probably related to the metabolic requirements of the nuclear layer and may play a role in wide field signal averaging and light adaptation.     

Light and electronmicroscope study of one of the systems of centrifugal fibers found in the lamina of muscoid flies

Summary By combining the Golgi and the electronmicroscope techniques it has been possible to identify accurately the system of centrifugal fibers which arborizes in the lamina of muscoid flies forming the so-called nervous bags. Each of them originates from a single fiber entering the lamina at the site in which the second order and the long visual fibers leave it. This single fiber represents the peripheral portion of a T-shaped trunk stemming from a small neuronal body located in the external region of the medulla. The central branch terminates within the first synaptic field of this visual center.After entering the lamina the centrifugal fiber ramifies profusely and its branches can be seen climbing and synapsing on the surface of the photoreceptor axon endings. The synaptic loci show characteristic synaptic ribbons located within the nervous bag fibers. This fact suggests that direction of conduction is from the medulla to the lamina. This study has also revealed that the intramedullar terminals of the centrifugal fibers establish intimate contacts with one of the two second order fiber endings.This work was supported by Grant No. 618–67 (Mod No. 67–0618) of the Office of Aerospace Research, United States Air Force and by NIH grant NSO 866901.     

衣藻(Chlamydomonas sp)中间纤维及核纤层存在的证实(简报)

衣藻(Chlamydomonas sp)是属于绿藻门的最低等单细胞植物,为典型的真核生物。迄今以衣藻为材料所作的有关细胞骨架方面的研究多集中在微管蛋白(tubulin)。C.J.Miller等曾以衣藻(Chlamydomonas reinhardtii)全蛋白与几种中间纤维抗体进行免疫印迹实验有阳性反应,但是衣藻中是否存在中间纤维与核纤层是不清楚的问题。衣藻中间纤维与核纤层的形态研究更未见报道。目前认为中间纤维-核纤     

On-off units in the first optic chiasm of the blowfly II. Spatial properties

We recorded from the spiking on-off unit in the first optic chiasm (between lamina and medulla) in the blowfly Calliphora vicina, and investigated its spatial properties. The receptive field extends over (11.4±0.9)° horizontally and (8.7±0.6)° vertically, i.e. about 7 by 5 interommatidial angles. The line spread function of the on-off unit — calculated from its response to moving sinusoidal gratings — has a half-width of (2.3±0.2)°. This half-width is slightly broader than that of the photoreceptor. Lateral inhibition occurs when two different areas of the receptive field are stimulated simultaneously. Fast temporal adaptation (i.e. adaptation to trains of short light pulses) takes place independently in different areas of the receptive field.     

The first optic ganglion of the bee

Summary The arrangement of first and second order neurons in an optic cartridge and the topographical relationships of the second order neurons within a cartridge and to groups of surrounding cartridges have been analyzed in the visual system of the bee, Apis mellifera, from light and electron microscope studies on Golgi preparations. At the level of the monopolar cell body layer, the nine retinula cell fibres of each ommatidium, the six short visual fibres arranged in a circle surrounding the three long visual fibres, become cartridges as a consequence of the appearance of the second order neurons (L-fibres) which join the R-fibre bundles. Two of the four different L-fibre types, L-1 and L-2, remain together in the centre of the cartridge throughout the lamina. The axons of the L-3 and L-4 fibres, however, have their position integrated into the circle formed by the endings of the short visual fibres. On the basis of further examination of light and especially electron microscopical Golgi material, the different L-fibres can be classified into four types which appear in each cartridge. The clear stratification in the first synaptic region (A, B and C) seems to be the best criterion for a morphological classification since such a classification necessarily also includes a functional basis. According to a naming system based on the position of the lateral processes, L-fibres with side branches in strata A, B and C are called L-1 fibres. Fibres with lateral processes in strata A and B are L-2 fibres; monopolar cell fibres with branches only in the second stratum B are L-fibres of type 3; and all monopolar cells with branches only in stratum C are called L-4 fibres. In addition to the branching pattern covering only the parent cartridge, two of the four fibre types (L-2 and L-4) have long collaterals reaching neighbouring cartridges: L-2 in stratum A and L-4 in stratum C. These collaterals presumably form a substrate for lateral interactions.     

厚度微创椎板间开窗椎管扩大术治疗腰椎管狭窄的疗效

目的:探讨微创椎板间开窗椎管扩大术治疗腰椎管狭窄(LSS)的疗效。方法:对收治的40例LSS患者(研究组)前瞻性实施微创椎板间开窗椎管扩大术治疗,回顾性分析实施常规后路椎板切除减压术治疗的40例LSS患者(对照组)的临床资料,术后随访6~24个月,对比两组患者治疗效果。结果:两组手术时间比较差异无统计学意义(P0.05),但研究组住院时间短于对照组,术中失血量少于对照组(P0.05);两组术后JOA评分有效率、轴性症状发生率、椎间隙高度、腰椎曲度、滑脱程度比较差异无统计学意义(P0.05),但研究组术后伤椎疼痛VAS评分显著低于对照组(P0.05);对照组并发症总发生率高于研究组(P0.05)。结论:微创椎板间开窗椎管扩大术治疗LSS,与常规术式疗效相当,但手术创伤小,术后并发症少。     

The plant nuclear envelope

This review summarizes our present knowledge about the composition and function of the plant nuclear envelope. Compared with animals or yeast, our molecular understanding of the nuclear envelope in higher plants is in its infancy. However, fundamental differences in the structure and function of the plant and animal nuclear envelope have already been found. Here, we compare and contrast these differences with respect to nuclear pore complexes, targeting of Ran signaling to the nuclear envelope, inner nuclear envelope proteins, and the role and fate of the nuclear envelope during mitosis. Further investigation of the emerging fundamental differences as well as the similarities between kingdoms might illuminate why there appears to be more than one blueprint for building a nucleus.Abbreviations GFP Green fluorescent protein - INE Inner nuclear envelope - LAP Lamina-associated polypeptide - LBR Lamin B receptor - MTOC Microtubule-organizing center - NE Nuclear envelope - NPC Nuclear pore complex - ONE Outer nuclear envelope - RanBP Ran-binding protein - RanGAP Ran GTPase-activating protein - WPP domain Tryptophan–proline–proline domain     

Mutations in Lama1 Disrupt Retinal Vascular Development and Inner Limiting Membrane Formation

The Neuromutagenesis Facility at the Jackson Laboratory generated a mouse model of retinal vasculopathy, nmf223, which is characterized clinically by vitreal fibroplasia and vessel tortuosity. nmf223 homozygotes also have reduced electroretinogram responses, which are coupled histologically with a thinning of the inner nuclear layer. The nmf223 locus was mapped to chromosome 17, and a missense mutation was identified in Lama1 that leads to the substitution of cysteine for a tyrosine at amino acid 265 of laminin α1, a basement membrane protein. Despite normal localization of laminin α1 and other components of the inner limiting membrane, a reduced integrity of this structure was suggested by ectopic cells and blood vessels within the vitreous. Immunohistochemical characterization of nmf223 homozygous retinas demonstrated the abnormal migration of retinal astrocytes into the vitreous along with the persistence of hyaloid vasculature. The Y265C mutation significantly reduced laminin N-terminal domain (LN) interactions in a bacterial two-hybrid system. Therefore, this mutation could affect interactions between laminin α1 and other laminin chains. To expand upon these findings, a Lama1 null mutant, Lama1^tm1.1Olf, was generated that exhibits a similar but more severe retinal phenotype than that seen in nmf223 homozygotes. The increased severity of the Lama1 null mutant phenotype is probably due to the complete loss of the inner limiting membrane in these mice. This first report of viable Lama1 mouse mutants emphasizes the importance of this gene in retinal development. The data presented herein suggest that hypomorphic mutations in human LAMA1 could lead to retinal disease.     

A new loach, Cobitis shikokuensis (Teleostei: Cobitidae), from Shikoku Island, Japan

A new species of spinous loach, Cobitis shikokuensis, is described based on 297 specimens from Shikoku Island, Japan. The new species was formerly known as the Shikoku group of Cobitis takatsuensis. It can be distinguished from other species of Cobitis and closely related genera by a combination of the following characters: dorsal fin with 6 branched soft rays; anal fin with 5 branched soft rays; one brownish streak across eye from the tip of nose, no streak on cheek; a black spot smaller than eye diameter near the dorsal corner of the caudal fin base; 3–5 small brownish speckles on ventral side of caudal peduncle; high caudal peduncle with well-developed fleshy keels on dorsal and ventral side; a lamina circularis at base of dorsal part of pectoral fin absent; first branched soft ray of pectoral fin broad in males; pectoral soft rays widely branched from the approximate midpoint; last anal fin ray with 2 elements; interorbital width 11.2–17.1% of head length.