scholarly journals OBSERVATIONS ON THE FINE STRUCTURE OF THE DEVELOPING SPERMATID IN THE DOMESTIC CHICKEN

1962 ◽  
Vol 14 (2) ◽  
pp. 193-205 ◽  
Author(s):  
Toshio Nagano
Keyword(s):  
Plasma Membrane ◽  
Fine Structure ◽  
Cross Section ◽  
Neck Region ◽  
Structural Features ◽  
Dense Granule ◽  
Domestic Chicken ◽  
The Other ◽  
Dense Structure ◽  
Distal Centriole

The kinetic apparatus, the acrosome and associated structures, and the manchette of the spermatid of the domestic chicken have been studied with the electron microscope. The basic structural features of the two centrioles do not change during spermiogenesis, but there is a change in orientation and length. The proximal centriole is situated in a groove at the edge of the nucleus and oriented normal to the long axis of the nucleus and at right angles to the elongate distal centriole. The tail filaments appear to originate from the distal centriole. The plasma membrane is invaginated along the tail filaments. A dense structure which appears at the deep reflection of the plasma membrane is identified as the ring. The fine structure of the ring has no resemblance to that of a centriole and there is no evidence that it is derived from or related to the centrioles. The tail of the spermatid contains nine peripheral pairs and one central pair of tubular filaments. The two members of each pair of peripheral filaments differ in density and in shape: one is dense and circular, and the other is light and semilunar in cross-section. The dense filaments have processes. A manchette consisting of fine tubules appears in the cytoplasm of the older spermatid along the nucleus, neck region, and proximal segment of the tail. The acrosome is spherical in young spermatids and becomes crescentic and, finally, U-shaped as spermiogenesis proceeds. A dense granule is observed in the cytoplasm between acrosome and nucleus. This granule later becomes a dense rod which is interpreted as the perforatorium.

scholarly journals THE AXON HILLOCK AND THE INITIAL SEGMENT

1968 ◽  
Vol 38 (1) ◽  
pp. 193-201 ◽  
Author(s):  
Sanford L. Palay ◽  
Constantino Sotelo ◽  
Alan Peters ◽  
Paula M. Orkand
Keyword(s):  
Plasma Membrane ◽  
Fine Structure ◽  
Granular Material ◽  
Internal Structure ◽  
Electron Micrographs ◽  
Initial Segment ◽  
Special Function ◽  
Structural Features ◽  
Dense Layer ◽  
Axon Hillock

Axon hillocks and initial segments have been recognized and studied in electron micrographs of a wide variety of neurons. In all multipolar neurons the fine structure of the initial segment has the same pattern, whether or not the axon is ensheathed in myelin. The internal structure of the initial segment is characterized by three special features: (a) a dense layer of finely granular material undercoating the plasma membrane, (b) scattered clusters of ribosomes, and (c) fascicles of microtubules. A similar undercoating occurs beneath the plasma membrane of myelinated axons at nodes of Ranvier. The ribosomes are not organized into Nissl bodies and are too sparsely distributed to produce basophilia. They vanish at the end of the initial segment. Fascicles of microtubules occur only in the axon hillock and initial segment and nowhere else in the neuron. Therefore, they are the principal identifying mark. Some speculations are presented on the relation between these special structural features and the special function of the initial segment.

Fine structure of antennal sensilla of the female sphinx moth, Manduca sexta (Lepidoptera: Sphingidae). II. Auriculate, coeloconic, and styliform complex sensilla

1999 ◽  
Vol 77 (2) ◽  
pp. 302-313 ◽  
Author(s):  
VDC Shields ◽  
J G Hildebrand
Keyword(s):  
Fine Structure ◽  
Manduca Sexta ◽  
Structural Features ◽  
The Other ◽  
Sensory Cells ◽  
Antennal Sensilla ◽  
Antennal Flagellum ◽  
Basiconic Sensilla ◽  
Female Antenna

The antennal flagellum of the female sphinx moth, Manduca sexta, bears eight types of sensilla: two trichoid, two basiconic, one auriculate, two coeloconic, and one styliform complex. We previously described the fine structure of the trichoid and basiconic sensilla (Shields and Hildebrand 1999). In this paper, we describe one type of auriculate, two types of coeloconic, and one type of styliform complex sensilla. The auriculate (ear- or spoon-shaped) sensillum is a small peg that averages 4 µm in length, is innervated by two bipolar sensory cells, and has structural features characteristic of an insect olfactory sensillum. Each of the two types of coeloconic sensilla is a small peg that averages 2 µm in length and is recessed in a cuticular pit. One type of coeloconic sensillum is innervated by five bipolar sensory cells and has structural features characteristic of an insect olfactory sensillum or olfactory-thermosensillum, while the other is innervated by three bipolar sensory cells and has structural features characteristic of an insect thermo-hygrosensillum. The styliform complex sensillum is a large peg that averages 38-40 µm in length and is formed by several contiguous sensilla, the number of which depends on the location of the peg on the flagellum. Each unit of the styliform complex sensillum is innervated by three bipolar sensory cells and has structural features characteristic of a thermo-hygrosensillum. We also ascertained the number and distribution of each of the eight types of sensilla on a single flagellomere (annulus) about midway along the flagellum of a female antenna. A total of 2216 sensilla were found on the dorsal, ventral, and leading surfaces of that annulus.

The fine structure of Thioploca araucae and Thioploca chileae

1990 ◽  
Vol 36 (6) ◽  
pp. 438-448 ◽  
Author(s):  
Siegfried Maier ◽  
Horst Völker ◽  
Marita Beese ◽  
Victor A. Gallardo
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Fine Structure ◽  
Coastal Upwelling ◽  
The Other ◽  
Surface Topology ◽  
Cytoplasmic Material ◽  
Transmission Electron ◽  
Soft Bottoms ◽  
Sulfur Inclusions

Thioploca araucae and Thioploca chileae from the sublittoral soft bottoms of the coastal upwelling ecosystem off central Chile were examined by scanning and transmission electron microscopy. Except for filament diameter (30–43 and 12–20 μm, respectively) and slight differences in other dimensions and surface topology, the details of fine structure were essentially identical in the two species. The wall consisted of five layers, and only the inner layer was present in the septum. Multiple membrane intrusions dissected the procaryotic cytoplasmic material, which was restricted to a relatively thin layer within the wall. Sulfur inclusions and two other extracytoplasmic inclusions, as well as one kind of intracytoplasmic inclusion, were described. The central part of each cell consisted of one large vacuole, extending from septum to septum and representing a volume at least more than three times larger than the combined volume of wall and cytoplasm. The vacuole was separated from the other cell parts by a membrane. Electron-dense material was deposited between vacuole membrane and plasma membrane, between plasma membrane and wall, and inside membrane intrusions. A continuity between the vacuolar membrane and the other membranes was never encountered. The possible origin of such an extracytoplasmic membrane is discussed. Key words: benthos, electron microscopy, fine structure, Thioploca.

scholarly journals UNE FORME MICROTUBULAIRE ET PARACRISTALLINE DE RETICULUM ENDOPLASMIQUE DANS LES PHOTOCYTES DES ANNELIDES POLYNOINÆ

1966 ◽  
Vol 31 (1) ◽  
pp. 135-158 ◽  
Author(s):  
J. M. Bassot
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Fine Structure ◽  
Nuclear Envelope ◽  
Contact Surface ◽  
Special Kind ◽  
The Other ◽  
Cytoplasmic Organelle ◽  
Specialized Form

Luminous cells of polynoid worm elytra have been examined by methods of electron microscopy, with special attention focused on the fine structure of photogenic grains. These cells send apical prolongations into the mid-part of the elytra. The plasma membrane is very sinuous, and a special kind of desmosome links two portions of the same membrane. In addition to all the organelles which can be found in nonluminescent epithelial cells of the elytra, numerous photogenic grains are contained in their cytoplasm. These grains are composed of undulating microtubules measuring 200 A in diameter; their disposition in the grain is highly regular, and the grains appear as paracrystals. At the borders of the grains, the walls of the microtubules are often in continuity with those of the endoplasmic reticulum and with the external membrane of the nuclear envelope. Because of this fact, the microtubules of the grains may be considered a cytoplasmic organelle, representing a specialized form of the endoplasmic reticulum. The microtubules permit the repartition, inside and outside their walls, of two different products, one being forty-three times more abundant than the other; thus, the contact surface, in comparison to the volume, is greatly increased. The induction of the luminous reaction by change in the permeability of the microtubule walls, allowing contact between the two substances, is suggested as a working hypothesis. There is an evolution of the grains along the axis of the photocytes. The grains are often surrounded by progressively increasing amounts of glycogen. Their paracrystalline disposition is altered at the apex of the luminous cells.

Ultrastructure of Spermatozoa of Elaphe schrenckii (Reptilia, Squamata)

2020 ◽  
Vol 27 (3) ◽  
pp. 149-155
Author(s):  
Shan-Shan Wang ◽  
Yu-Yan Lu ◽  
Chen-Hao Yao ◽  
Shuo Qi ◽  
Jian-Xin Cheng ◽  
...  
Keyword(s):  
Cross Section ◽  
Neck Region ◽  
Base Plate ◽  
Laminar Structure ◽  
Fibrous Sheath ◽  
Dense Bodies ◽  
Transmission Electron ◽  
Principal Piece ◽  
Distal Centriole ◽  
The Stability

Elaphe schrenckii (Serpentes, Colubridae), a kind of large nonvenomous snakes and great significance to maintain the stability of ecosystem in China. We provide detailed descriptions of the sperm microstructure and ultrastructure of E. schrenckii, experimented by light microscope and transmission electron microscope. The spermatozoon of E. schrenckii is filiform and consists of head and tail regions. The cross-section of acrosomal vesicle is always rounded and divided into medulla inside and cortex outside. The ultrastructure of acrosome complex observed the unilateral ridge, the single perforatorium, the perforatorium base plate, the epinuclear lucent zone, the subacrosomal space and the nuclear fossa at the end of nucleus connect the neck region. The neck region is short with the stratified laminar structure and observed the distal centriole and the proximal centriole are perpendicular and both consisted of nine triplets. Midpiece is long and observed the extracellular microtubules, the multilaminar membranec, the mitochondria with the dense bodies discontinuity distribting, the fibrous sheath, and the axoneme. The principal piece is after the annulus with no mitochondrias and the end piece with no mitochondrias neither the fibrous sheath. Our study contrasted the spermatozoa ultrastructure of 8 species belong to 5 families and 6 genera and added the sperm measurement compare, summarized that three Colubridae snakes are more similar than others momentarily but some specific characteristics in E. schrenckii and proved that the ultrastructure of sperm related to phylogeny in some ways.

Roots and the delivery of solutes to the xylem

1993 ◽  
Vol 341 (1295) ◽  
pp. 5-17 ◽  
Keyword(s):  
Plasma Membrane ◽  
Physiological State ◽  
Turgor Pressure ◽  
Xylem Sap ◽  
Neck Region ◽  
Structural Features ◽  
Wall Thickening ◽  
Recent Information ◽  
Common Structure ◽  
New Findings

The structural features of the pathways followed by solutes and water are described. The porous nature of the cell walls comprising the apoplasm is described and the difficulties in verifying the passage of water through different parts of the apoplasm are discussed. The endoderm is of ubiquitous occurrence and has two invariant characteristics, a girdle-like wall thickening, the Casparian band, and the attachment of the plasma membrane to the band. Suggestions are made concerning the constraints placed on the passage of materials in the stele by these structures. The hypodermis is also a very common structure which shares a number of properties seen in the endodermis. The implications of an apoplasmic barrier in the hypodermis are discussed. The plasmodesmata are the key structural feature of the symplasmic pathway and recent information makes it clear that the size of the pores in the neck region can vary with the physiological state and position of tissues. The symplasmic pathway seems not to be interrupted by structural developments which make the endodermis an apoplasmic barrier of high resistance. Recent information from transpiring plants indicates that the turgor pressure in cortical cells increases centripetally: there is, therefore an outwardly directed hydrostatic pressure gradient. The implications of these new findings for water and solute flows in the symplast are considered. The final step in the radial transfer of materials is their release into the xylem. There is evidence that stelar tissues contain an H + -translocating ATPase whose activity can be influenced by physiological factors. It is pointed out that there may be major changes in the concentration of K + in xylem sap during a day-night cycle which may influence the polarization of the cell membranes of xylem parenchyma and the opening of ion-channels. The xylem elements themselves are not always fully conductive, even when their final diameter has been reached. The protoplasts and cross walls may be more persistent than is usually assumed, especially in soil-grown roots. Because of the low activity of Ca 2+ in the cytoplasm and the discontinuity of compartments within cells which contain abundant free Ca 2+ , this ion probably moves radially primarily by diffusion in the apoplasm. The transfer of Ca +2 across the endodermis is shown to depend on the activity of Ca 2+ ATPase in the plasma membrane of the stelar side of the endodermis, emphasising once again the epithelial nature of this cell layer.

Ultrastructure and Staining of Developing Elastic Tissue

1971 ◽  
Vol 29 ◽  
pp. 244-245
Author(s):  
E. N. Albert
Keyword(s):  
Fine Structure ◽  
Phosphotungstic Acid ◽  
Staining Method ◽  
Rat Aorta ◽  
Uranyl Acetate ◽  
The Other ◽  
Elastic Fibers ◽  
Elastic Tissue ◽  
Lead Citrate ◽  
New Born

Silver tetraphenylporphine sulfonate (Ag-TPPS) was synthesized in this laboratory and used as an electron dense stain for elastic tissue (Fig 1). The procedures for the synthesis of tetraphenylporphine sulfonate and the staining method for mature elastic tissue have been described previously.The fine structure of developing elastic tissue was observed in fetal and new born rat aorta using tetraphenylporphine sulfonate, phosphotungstic acid, uranyl acetate and lead citrate. The newly forming elastica consisted of two morphologically distinct components. These were a central amorphous and a peripheral fibrous. The ratio of the central amorphous and the peripheral fibrillar portion changed in favor of the former with increasing age.It was also observed that the staining properties of the two components were entirely different. The peripheral fibrous component stained with uranyl acetate and/or lead citrate while the central amorphous portion demonstrated no affinity for these stains. On the other hand, the central amorphous portion of developing elastic fibers stained vigorously with silver tetraphenylporphine sulfonate, while the fibrillar part did not (compare figs 2, 3, 4). Based upon the above observations it is proposed that developing elastica consists of two components that are morphologically and chemically different.

A New Approach to the Demonstration of Oxidase-Localization Using Tannic Acid Or Catechin

1973 ◽  
Vol 31 ◽  
pp. 698-699
Author(s):  
V. Mizuhira ◽  
Y. Futaesaku
Keyword(s):  
Cross Section ◽  
Tannic Acid ◽  
Elastic Fiber ◽  
The Other ◽  
New Approach ◽  
Tissue Block ◽  
Active Reaction ◽  
The Cross

Previously we reported that tannic acid is a very effective fixative for proteins including polypeptides. Especially, in the cross section of microtubules, thirteen submits in A-tubule and eleven in B-tubule could be observed very clearly. An elastic fiber could be demonstrated very clearly, as an electron opaque, homogeneous fiber. However, tannic acid did not penetrate into the deep portion of the tissue-block. So we tried Catechin. This shows almost the same chemical natures as that of proteins, as tannic acid. Moreover, we thought that catechin should have two active-reaction sites, one is phenol,and the other is catechole. Catechole site should react with osmium, to make Os- black. Phenol-site should react with peroxidase existing perhydroxide.

Electron Irradiation Effects in Polyoxymethylene Crystals Grown Inside Trioxane Crystals

1971 ◽  
Vol 29 ◽  
pp. 78-79
Author(s):  
J. P. Colson ◽  
D. H. Reneker
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Detailed Examination ◽  
The Other ◽  
Electron Micrograph ◽  
Irradiation Effects ◽  
Threefold Axis ◽  
Typical Sample ◽  
Polymer Crystals ◽  
Chain Axis

Polyoxymethylene (POM) crystals grow inside trioxane crystals which have been irradiated and heated to a temperature slightly below their melting point. Figure 1 shows a low magnification electron micrograph of a group of such POM crystals. Detailed examination at higher magnification showed that three distinct types of POM crystals grew in a typical sample. The three types of POM crystals were distinguished by the direction that the polymer chain axis in each crystal made with respect to the threefold axis of the trioxane crystal. These polyoxymethylene crystals were described previously.At low magnifications the three types of polymer crystals appeared as slender rods. One type had a hexagonal cross section and the other two types had rectangular cross sections, that is, they were ribbonlike.

Further Studies on the Ultrastructure of Harderian Gland in Adult Rats

1974 ◽  
Vol 32 ◽  
pp. 288-289
Author(s):  
Alfredo Feria-Velasco ◽  
Guadalupe Tapia-Arizmendi
Keyword(s):  
Fine Structure ◽  
Domestic Fowl ◽  
Animal Species ◽  
Acinar Cells ◽  
Harderian Gland ◽  
Myoepithelial Cells ◽  
The Other ◽  
Albino Rats ◽  
Adult Rats ◽  
Cell Components

The fine structure of the Harderian gland has been described in some animal species (hamster, rabbit, mouse, domestic fowl and albino rats). There are only two reports in the literature dealing on the ultrastructure of rat Harderian gland in adult animals. In one of them the author describes the myoepithelial cells in methacrylate-embbeded tissue, and the other deals with the maturation of the acinar cells and the formation of the secretory droplets. The aim of the present work is to analize the relationships among the acinar cell components and to describe the two types of cells located at the perifery of the acini.

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