Juxtanuclear changes during the early spermatogenesis in Lebistes reticulatus (Guppy)

Summary The sperm cell of Lebistes reticulatus during Spermatogenesis is studied. The nuclear differentiation correlate to the flagellar outgrowth. Differential distribution in the chromatin condensation corresponds to a new membrane synthesis at the centriolar side of the nucleus. The fan-shaped microtubular bundle in Juxtanuclear position is described and its function as a stabilizing entity is discussed. At the centriolar complex satellites and an intercentriolar lamellated body are investigated. In submicroscopic details the sperm cell of Lebistes distinctively differs from other species previously described.The present investigation was supported by a grant from the Pehr Oscar Klingendahl Foundation.The authors wish to thank Mr. Mauri Nyholm, M. Sc., for his technical advices and Miss Maria Sjöstedt for preparing the specimens.     

Microscopic anatomy of the integument in the ribbon worm Micrura bella (Stimpson, 1857) (Pilidiophora,Nemertea)

The integument of ribbon worms in the order Heteronemertea is distinct from the integuments in the other taxa of nemerteans due to the presence of a special subepidermal glandular layer, the cutis. Among heteronemerteans, the ultrastructure of the cutis has been studied only in the Lineus ruber species complex. In the current study, ultrastructural (transmission electron microscopy) and histochemical studies of the epidermis and the cutis of Micrura bella from the basal Lineage A of the family Lineidae were performed. The epidermis consisted of ciliated and serous gland cells and is separated from the cutis by a layer of the subepidermal extracellular matrix; the basal lamina was not detected. The cutis comprised musculature, two types of mucous and four types of granular gland cells, and pigment cells with four types of granules. In the cutis of juvenile worms, type II granular gland cells and type II mucous cells were not observed. The integument of the caudal cirrus consisted of ciliated and serous gland cells and two intraepidermal lateral nerve cords; the cutis was absent. The compositions of the integument glands of M. bella and the L. ruber species complex are similar, except for the presence of type IV granular gland cells with narrow rod-shaped and lamellated granules exhibiting an alternating dark and light transverse layers and type II mucous cells found only in M. bella.     

The Pollen of Swedish Callitriche (Callitrichaceae) - Trends Towards Submergence

The pollen morphology of the six Swedish Callitriche L. species was investigated using LM, SEM and TEM. The surface ornamentation is reticulate in C. stagnalis, C. platycarpa, C. cophocarpa and C. palustris with supratectal elements in the first three species. The ectexine is reduced in C. hamulata, occurring as scattered granules, but completely absent in C. hermaphroditica. None of the species has distinct apertures but C. cophocarpa and C. platycarpa both have leptomata. The ultrastructure of the pollen wall in C. palustris shows regions with lamellated footlayer and an endexine which may function as apertures. Pollen morphology is found to be related to pollination biology; species with leptomata sometimes being pollinated through ephydrophily and species with reduced exine being hyphydrophilous.     

Localization of the lamellated corpuscle neurons of the cat large intestine mesentery

Electrical activity and ultrastructure of lamellated corpuscles (Pacinian corpuscles) of the cat large intestine mesentery were studied 10 days after uni- and bilateral extirpation of the lumbar spinal ganglia. Terminal degenerated in all the receptors, and there were no electrical reactions at bilateral extripation of ganglia L3-L4, they were preserved in some receptors at bilateral extirpation of ganglia L2-L3 and L4-L5 and at unilateral extirpation of ganglia L3-L4. Structure of the receptors and electrical reactions were preserved in all the lamellated corpuscles at bilateral extirpation at the level of L1-L2 and L5-L6. After enucleation of the corpuscles from the large intestine mesentery, in some neurons of ganglia L3-L4, chromatolysis was observed. After the caudal mesenteric nerve was sectioned, there were no electrical reactions in the lamellated corpuscles of the large intestine mesentery. Hence, the sensitive neurons-theri peripheral processes participate in the formation of the lamellated corpuscles of the cat large intestine mesentery-are situated in the lumbar ganglia L3 and L4.     

Ultrastructure of the dendritic outer segments of sensory cells in poreless (‘no-pore’) sensilla of insects

Summary Poreless sensilla with inflexible sockets in insects presumably house hygro- and thermoreceptors (type-1, type-2 receptors). The dendritic outer segments of these receptor cells were studied mainly in cryofixed antennae of two species of moth (Antheraea pernyi, A. polyphemus) and one beetle (Aleochara curtula). As a rule two type-1 receptor cells are present. Their dendritic outer segments do not branch. They project into the distal cuticular parts of the sensillum and are in close contact with its four-layered wall. The segments differ in shape and microtubule density. As well, in A. curtula, the microtubules are interconnected by electron-dense material for some distance, thus forming a tubular body-like structure of 1.3 m length. The dendritic outer segment of the single type-2 receptor cell is branched and lamellated. Its lamellae are connected by structures similar to septate junctions, which occupy about 70% of the total surface of the lamellated portion of the dendrite. In tangential sections, the septa appear as parallel strands approximately perpendicular to the long axis of the dendritic segment. The structure of type-1 receptors is discussed with regard to the hypothesis for a mechano-electrical transduction. The possible functions of lamellation and junctional connections in type-2 receptors are discussed.Supported by the Deutsche Forschungsgemeinschaft (SFB 4/G1)     

ANATOMICAL DISTINCTIONS BETWEEN THE PISTILLATE SPIKELETS OF THE SPECIES OF WILD-RICE (ZIZANIA,POACEAE)

The most reliable macromorphological characters that can be used to discriminate between the annual species of the genus Zizania are found in the pistillate spikelet. One aspect of this morphology is a textural dimorphism. The pistillate lemmas and paleas of Z. aquatica are chartaceous (papery) whereas those of Z. palustris are coriaceous (leathery). Pistillate lemmas and paleas of the two perennial species, Z. texana and Z. latifolia, are also chartaceous. To determine the anatomical basis for the nature of this character, pistillate lemmas and paleas were either fixed, treated with hydrofluoric acid, and sectioned; or fresh material was sectioned on a freezing microtome. Those with a chartaceous texture were found to have a single layer of thin-walled, subepidermal fibers whereas those with a coriaceous texture had at least two layers of thick-walled, subepidermal fibers.     

First description of mechanoreceptors in the corpus adiposum infrapatellare of man

The sensory innervation of the corpus adiposum infrapatellare of the human knee joint was studied by light microscopy. Small lamellated corpuscles (pacinian corpuscles) were found in the adipose tissue of the corpus adiposum infrapatellare. The lamellated corpuscles measured about 20 microns and consisted of 3-4 lamellae. It is discussed whether the corpus adiposum infrapatellare might perform a sensory function, influencing the muscle tone via polysynaptic reflexes.     

Ultrastructure of antennal sense organs of small ermine moths,Yponomeuta spp. (Lepidoptera : Yponomeutidae)

The ultrastructure of antennal sensilla was investigated in males and females of 5 European Yponomeuta species. Three types of olfactory sensilla could be distinguished, i.e. sensilla trichodea, sensilla basiconica, and sensilla coeloconica. Sexual dimorphism in the number of cells innervating sensilla trichodea could be established in 3 species. Most of these sensilla in males of Y. vigintipunctatus, Y. rorellus, and Y. cagnagellus are associated with 3 sensory cells, whereas in females of these species these sensilla contain 2 sensory cells. In both males and females of Y. padeltus and Y. malinellus, the great majority of the sensilla trichodea is innervated by 3 cells. So-called sensilla chaetica type 1 show features typical of a combined mechano/contact-chemoreceptor. No structures indicating a sensory function were found in sensilla chaetica type 11. Sensilla styloconica contain 3 cells, the dendritic outer segment of one being lamellated; most likely, these cells have a thermo- and hygroreceptive function. The findings concerning the olfactory sensilla are discussed in the context of olfactory communication and reproductive isolation in European Yponomeuta.     

Comparative observations on inclusions in nerve fibres of the mammalian neurohypophysis

Summary A comparative study has been made of the inclusions within neurohypophysial nerve fibres of eight species of mammals.Four classes of small inclusions have been found in each of these species, namely small and large membranous vesicles, and small and large osmiophilic membrane-bound granules. No inclusions resembling the rod-shaped inclusions in the hedgehog's neurohypophysis have been found. It seems probable that more than one type of neurosecretory fibre occurs in the infundibular process of all these species.Large lamellated structures were found in some species, and these possibly give rise to membranous vesicles.     

Lamellated outer dendritic segments of a chemoreceptor within wall-pore sensilla in the labial palp-pit organ of the butterfly,Pieris rapae L. (Insecta,Lepidoptera)

Summary The structure of the sensilla in the apical pit of the third segment of the labial palps in Pieris rapae was investigated in cryofixed and chemically fixed specimens. There is a field of about 80 club-shaped sensilla, 94% of which house a single sensory cell; 6% contain two sensory cells. All sensory cells are of the same type and are characterized by the structure of the dendritic outer segment. This consists of a proximal cylindrical and a distal lamellated section. The lamellae contain a lattice of longitudinally arranged microtubules. Filamentous strands connect the microtubules with the surface membrane of the lamellae. The surface area of the lamellated section amounts to about 40 m². Pores and pore tubules are present in the cuticular wall of the peg. Electrophysiological recordings show that the sensory cells are olfactory receptors, which react to a variety of complex plant odors and to the odor of conspecifics. It is shown that (a) the usual modality-specific characteristics of insect olfactory sensilla apply here also; (b) lamellation is not only a characteristic of thermoreceptors, but also of olfactory chemoreceptors; (c) there are pore tubules that are separated from the dendritic membranes by an extended dendritic sheath; and (d) in the labial palppit sensilla only the lamellated dendritic tip region may be involved in sensory transduction.Supported by the Deutsche Forschungsgemeinschaft (SFB 4/G1)     

Structural studies on lamellated osmiophilic bodies isolated from pig lung. 31P NMR results and water content

1. Lamellated osmiophilic bodies are intracellular organelles in which pulmonary surfactant is stored prior to secretion. They contain about 85% phospholipid (per dry weight) and dipalmitoyl phosphatidylcholine is a major constituent, and although their ultrastructure is uncertain it is generally supposed that they resemble liposomes. However, liposomes are stable because layers of water are interposed between the lipid bilayers whereas an essential aspect of the function of lamellated bodies is that, subsequent to their secretion, they are rapidly disrupted to form a surface-active film which covers the respiratory epithelium of the lung. 2. A new method for isolating lamellated bodies from pig lung is described which has the advantage of speed and simplicity and which results in increased yields. The homogeneity of the preparation is similar to that obtained by other methods. 3. 31P NMR spectra of lamellated bodies showed that at 40 degrees C about 95% of the phospholipid was present as extended bilayers and that about 5% was present in a phase exhibiting isotropic head group mobility (tau R less than 10(-5) s). It is suggested that this phase may be due to apolar proteins which are present both in lamellated bodies and in liposomes prepared from lipids extracted from them. 4. The internal water content of lamellated bodies has been measured gravimetrically and the hydration of the phospholipid head groups has been examined by 31P NMR. The two methods gave results in good agreement and show that there are about seven molecules of water/molecule of phospholipid. It is concluded that although the phospholipid head groups in lamellated bodies are fully hydrated, there is no zone of free water. 5. Lamellated bodies are osmotically insensitive to NaCl whereas liposomes prepared from lipids extracted from them behave like perfect osmometers. It is suggested that the osmotic insensitivity and restricted water content of lamellated bodies are important to their function and dependent upon polar proteins in the outer limiting membrane.     

Foliar anatomy ofPolygonum (Polygonaceae): Survey of epidermal and selected internal structures

Several anatomical characters in leaves were described, and their distribution determined, for 153 species ofPolygonum, mostly from herbarium specimens. Structures surveyed were epidermal (glandular and nonglandular trichomes, nodules, specialized parenchyma, stomatal apparatus) and internal (cavities, crystals, laticifer-like cells, nodules, subepidermal fibers). Cleared leaves were supplemented by resin-embedded sections and SEM preparations of selected species. No feature defines any taxonomic section, but some features occur only within one section. Laticifer-like cells, epidermal and internal nodules, resin cups, and unique epidermal and subepidermal cavities seem to be unknown elsewhere; other features (invaginated epidermal cells; enlarged crystal cells confined to paraveinal layer) are rare among angiosperms.     

The alveolar epithelium of the newborn rat,and the significance of the osmiophilic lamellated bodies in cellular autophagy

Abstract

An attempt was made to determine the nature, origin, and fate of the membrane material of osmiophilic lamellated bodies, using lung tissue from neonate rats. The cytoplasm of the type II alveolar pneumonocyte contains centrioles, multivesicular bodies, and minute free vesicles similar to those in the multivesicular bodies. Autolysosomes, comprising membrane-bounded cytoplasmic regions and osmiophilic lamellated material, also occur in the type II pneumonocytes. The mitochondria often contain concentric membrane accumulations and membranous whorls. The type II alveolar cells are characterised by an intensive autophagy; this is apparently correlated with glycogenolysis, and with a radical cytodifferentiation by which the cells transform to the type I pneumonocyte. The osmiophilic lamellae of the autolysosomes are probably emptied isolation membranes. The mitochondria possibly serve as repositories for the massive membrane accumulations remaining after cytoplasmic lysis, which may invaginate into the organelles. The osmiophilic lamellated bodies typical of type II alveolar pneumonocytes may be mitochondrial membranes packed with the residual membranous material. Myeloid matter in the alveolar spaces (derived from the osmiophilic lamellated bodies) is best interpreted, not as an organised secretory product, but rather as a residue of cellular autophagy.     

Structure of subepidermal tissue of gamasid mites (electron microscopy data)

Fine structure of the subepidermal tissue was investigated in the adult predatory mite Hypoaspis miles (Gamasina: Laelapidae) and bloodsucking mite Dermanyssus gallinae (Gamasinae: Dermanyssidae) of both sexes. This tissue is analogous to the fat body of other arthropodes. The subepidermal tissue of females consists of two types of cells: cells containing a synthetic apparatus and secretory granules; cells containing storage substances. In the subepidermal tissue of H. miles, cells being similar to hemocytes were also observed. As the males of both species have only one cell type in this tissue--the storage one and the females have the secretory cells, it is suggested that the subepidermal tissue of females could probably take part in the vitellogenesis.     

Functional Analyses of Bitter Taste Receptors in Domestic Cats (Felis catus)

Cats are obligate carnivores and under most circumstances eat only animal products. Owing to the pseudogenization of one of two subunits of the sweet receptor gene, they are indifferent to sweeteners, presumably having no need to detect plant-based sugars in their diet. Following this reasoning and a recent report of a positive correlation between the proportion of dietary plants and the number of Tas2r (bitter receptor) genes in vertebrate species, we tested the hypothesis that if bitter perception exists primarily to protect animals from poisonous plant compounds, the genome of the domestic cat (Felis catus) should have lost functional bitter receptors and they should also have reduced bitter receptor function. To test functionality of cat bitter receptors, we expressed cat Tas2R receptors in cell-based assays. We found that they have at least 7 functional receptors with distinct receptive ranges, showing many similarities, along with some differences, with human bitter receptors. To provide a comparative perspective, we compared the cat repertoire of intact receptors with those of a restricted number of members of the order Carnivora, with a range of dietary habits as reported in the literature. The numbers of functional bitter receptors in the terrestrial Carnivora we examined, including omnivorous and herbivorous species, were roughly comparable to that of cats thereby providing no strong support for the hypothesis that a strict meat diet influences bitter receptor number or function. Maintenance of bitter receptor function in terrestrial obligate carnivores may be due to the presence of bitter compounds in vertebrate and invertebrate prey, to the necessary role these receptors play in non-oral perception, or to other unknown factors. We also found that the two aquatic Carnivora species examined had fewer intact bitter receptors. Further comparative studies of factors driving numbers and functions of bitter taste receptors will aid in understanding the forces shaping their repertoire.     

Abundant accumulation of the calcium-binding molecular chaperone calreticulin in specific floral tissues of Arabidopsis thaliana.

Calreticulin (CRT) is a calcium-binding protein in the endoplasmic reticulum (ER) with an established role as a molecular chaper-one. An additional function in signal transduction, specifically in calcium distribution, is suggested but not proven. We have analyzed the expression pattern of Arabidopsis thaliana CRTs for a comparison with these proposed roles. Three CRT genes were expressed, with identities of the encoded proteins ranging from 54 to 86%. Protein motifs with established functions found in CRTs of other species were conserved. CRT was found in all of the cells in low amounts, whereas three distinct floral tissues showed abundant expression: secreting nectaries, ovules early in development, and a set of subepidermal cells near the abaxial surface of the anther. Localization in the developing endosperm, which is characterized by high protein synthesis rates, can be reconciled with a specific chaperone function. Equally, nectar production and secretion, a developmental stage marked by abundant ER, may require abundant CRT to accommodate the traffic of secretory proteins through the ER. Localization of CRT in the anthers, which are degenerating at the time of maximum expression of CRT, cannot easily be reconciled with a chaperone function but may indicate a role for CRT in anther maturation or dehiscence.     

Elektronenmikroskopische Untersuchungen zur funktionellen Morphologie der borstenführenden Hautsinnesorgane beiTarentola mauritanica L. (Reptilia,Gekkonidae)

Zusammenfassung Die borstenführenden Hautsinnesorgane vonTarentola mauritanica sind in die Epidermis eingesenkt und besitzen aufgrund ihrer Hüllzellen eine verdickte Basis. Jedes Organ befindet sich jeweils über dem dazugehörigen Nerv. Nach seinem Eintritt in das Organ kann man Axone beobachten, die die Sensille in distaler Richtung durchziehen.Die Hüllzellen umgeben in der Hauptsache zwei gro\e epidermale Zentralzellen, zwischen denen die Axone unter starker Invagination verlaufen. Die Zentralzellen reichen bis zur distalen Zellschicht der Äu\eren Epidermisgeneration. Die Axone invaginieren nach Verlassen des Zentralzellenbereichs in diese Schicht und bilden dort 10–15 Terminalblasen, die als Stellen der Reizaufnahme anzusehen sind. Sie liegen nahe unterhalb des Sensillendeckels, der oft mehrere lange Zentralborsten aufweist. Eine Auslenkung der Borsten dürfte sich als Deformation des Deckels auswirken, der wesentlich dünner ist als das OberhÄutchen au\erhalb des Sensillenbereichs.Die Bedeutung der Sensillen auf den Zehenrandschuppen liegt in der Kontrolle der Zehenbewegung und in der FÄhigkeit, Wasser aufgrund der OberflÄchenspannung zu perzipieren. Bei Kontakt mit feuchten Medien werden die Zehen augenblicklich dorsal aufgerollt und die Haftborsten so vor Verklebung geschützt.

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Ultrastructure and function of the setae-bearing cutaneous sensory organs inTarentola mauritanica L. (Reptilia, Gekkonidae)

Summary The ultrastructural organization of the setae-bearing sensilla has been elucidated with regard to their position on the scales, their surface structure and their presumable functions. These sensilla have a thickened basis caused by enveloping epithelial cells. Each organ is situated above the appropriate nerve. Entering the organ, this nerve ramifies into axons, which continue between two great central-positioned cells of epidermal origin as far as to the top of them. The central cells end beneath the distal layer of the outer epidermal generation. Leaving the central cells at their top, the axons invaginate into this layer and form, corresponding to the number of axons, 10–15 terminal vesicles. These terminals are — according to recent ultrastructural findings — presumably able to registrate (mechanical) stimuli. The terminals are embedded in masses of tonofibrils, especially at their bases. At the flattened top of the organ long setae are situated centrally but without any direct contact to lower parts of the organ. Mechanical bending of the setae will deform the top of the sensillum which will be recorded by the terminal receptors described.The movement of the toes is controlled by the sensilla of the scales surrounding the toes, which is important for the climbing mechanism. A decisive function of these organs is the perception of water or other wet substrata. When touching this, the geckos will immediately roll up their toes thus protecting their bristles of the footpads from sticking together.

     

Lamellated bodies in the neurons of the submucosal ganglia in the sphincter of Oddi of the dog.

Peculiar neurons and nerve processes, which contained remarkable amounts of lamellated, electron-dense bodies, "myeloid bodies", are described. They were found among normal looking neurons in the submucosal ganglia of the sphincteric musculature of Oddi. The innervation and ultrastructure of the ganglia were studied in apparently healthy, young dogs bred for experimental purposes. The possible function of these neurons and processes is discussed.     

Compartmentation of Zinc in Roots and Leaves of the Zinc Hyperaccumulator Thlaspi caerulescens J & C Presl

Thlaspi caerulescens is a metallophyte that is able to hyperaccumulate Zn. In the present study the subcellular compartmentation of Zn was investigated in roots and leaves of this species by means of X-ray microanalysis. Leaves accumulated higher average Zn concentrations than roots. In roots of plants exposed to 10 μM Zn, Zn concentrations in the apoplast were similar to those in vacuoles, while in plants treated with 100 μM Zn considerably higher Zn concentrations were detected in vacuoles than in the apoplast. In epidermal and sub-epidermal cells of leaves of plants from both treatments, Zn mainly accumulated in vacuoles and, to a lesser extent, in the apoplast. In vacuoles from plants exposed to 100 μM Zn, high Zn concentrations were associated with variable amounts of P, Ca and K. In leaves, the highest Zn concentrations (13,600 μg g^?1 d.m.) were found in globular crystals present in many vacuoles of epidermal and subepidermal cells. Smaller deposits with a variable Zn concentration between 1,000 and 18,300 μg g^?1 d.m. were observed in the epidermal and subepidermal cells of roots. Both the high Zn/P element ratios found in the crystals and the absence of Mg indicate that, in contrast to other plant species, myo-inositol hexaphosphate (phytate) is not the main storage form for Zn in Thlaspi caerulescens.