scholarly journals OBSERVATIONS ON THE DEVELOPMENT OF ERYTHROCYTES IN MAMMALIAN FETAL LIVER

1962 ◽  
Vol 14 (2) ◽  
pp. 235-254 ◽  
Author(s):  
Joseph A. Grasso ◽  
Hewson Swift ◽  
G. Adolph Ackerman
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Nuclear Envelope ◽  
Cell Size ◽  
Marked Decrease ◽  
Fetal Liver ◽  
Hepatic Parenchyma ◽  
Hemoglobin Synthesis ◽  
Hepatic Cells ◽  
Eventual Loss

The fine structure of the erythrocyte during development in rabbit and human fetal liver has been studied. A morphologic description of representative erythropoietic cells and their relationship to the hepatic parenchyma is presented. Erythrocyte development was accompanied by a decrease in nuclear and cell size, fragmentation and eventual loss of nucleoli, and progressive clumping of chromatin at the nuclear margin. Mitochondria, endoplasmic reticulum, and Golgi elements decreased in size or abundance and eventually disappeared. Ribosome concentration initially increased, but subsequently diminished as the cytoplasm increased in electron opacity, probably through the accumulation of hemoglobin. Similar dense material, interpreted to be hemoglobin, infiltrated the nuclear annuli and, in some cases, appeared to extend into the interchromatin regions. There was a marked decrease in the number of annuli of the nuclear envelope. Possible relationships between nucleus and cytoplasm and of RNA to hemoglobin synthesis are discussed. In rabbits, erythroid and hepatic cells were separated by a 200 to 400 A space limited by the undulatory membranes of the respective cells. Membranes of adjacent erythropoietic cells were parallel and more closely apposed (100 to 200 A). In humans, relationship between various cells exhibited wide variation. Ferritin particles were observed within forming and formed "rhopheocytotic" vesicles.

scholarly journals FINE STRUCTURE AND ORGANELLE ASSOCIATIONS IN BROWN ALGAE

1965 ◽  
Vol 26 (2) ◽  
pp. 523-537 ◽  
Author(s):  
G. Benjamin Bouck
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Golgi Apparatus ◽  
Nuclear Envelope ◽  
Brown Algae ◽  
Algal Cell ◽  
Plant Cells ◽  
Membrane Systems ◽  
Two Envelopes

The structural interrelationships among several membrane systems in the cells of brown algae have been examined by electron microscopy. In the brown algae the chloroplasts are surrounded by two envelopes, the outer of which in some cases is continuous with the nuclear envelope. The pyrenoid, when present, protrudes from the chloroplast, is also surrounded by the two chloroplast envelopes, and, in addition, is capped by a third dilated envelope or "pyrenoid sac." The regular apposition of the membranes around the pyrenoid contrasts with their looser appearance over the remainder of the chloroplast. The Golgi apparatus is closely associated with the nuclear envelope in all brown algae examined, but in the Fucales this association may extend to portions of the cytoplasmic endoplasmic reticulum as well. Evidence is presented for the derivation of vesicles, characteristic of those found in the formative region of the Golgi apparatus, from portions of the underlying nuclear envelope. The possibility that a structural channeling system for carbohydrate reserves and secretory precursors may be present in brown algae is considered. Other features of the brown algal cell, such as crystal-containing bodies, the variety of darkly staining vacuoles, centrioles, and mitochondria, are examined briefly, and compared with similar structures in other plant cells.

scholarly journals PEROXIDASE ACTIVITY IN RAT LIVER MICROBODIES AFTER AMINO-TRIAZOLE INHIBITION

1970 ◽  
Vol 45 (3) ◽  
pp. 576-585 ◽  
Author(s):  
Richard L. Wood ◽  
Peter G. Legg
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Golgi Apparatus ◽  
Peroxidase Activity ◽  
Catalase Activity ◽  
Staining Technique ◽  
Male Rats ◽  
Hepatic Cells ◽  
In Vivo Effects

The in vivo effects of 3-amino-1,2,4-triazole (AT) on the fine structure of microbodies in hepatic cells of male rats has been studied by the peroxidase-staining technique. Within 1 hr of intraperitoneal injection AT abolishes microbody peroxidase-staining, and the return of staining coincides temporally with the known pattern of return of catalase activity following AT inhibition; this is further evidence that the peroxidase staining of microbodies is due to catalase activity. Peroxidase staining reappears in the microbody matrix without evidence of either massive degradation or rapid proliferation of the organelles. Furthermore, during the period of return of activity, ribosomal staining occurs adjacent to microbodies whose matrix shows little or no peroxidase staining. These observations are interpreted as evidence that (a) catalase is capable of entering preexisting microbodies without traversing the cisternae of the rough endoplasmic reticulum or the Golgi apparatus, and that (b) the ribosomal staining is probably not cytochemical diffusion artifact and may represent a localized site of synthesis or activation of catalase.

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.

Fine Structure of the Cytoplasm in Salivary Glands of Simulium

1967 ◽  
Vol 2 (1) ◽  
pp. 137-144
Author(s):  
H. C. MACGREGOR ◽  
J. B. MACKIE
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Nuclear Envelope ◽  
Salivary Glands ◽  
Rough Endoplasmic Reticulum ◽  
Salivary Secretion ◽  
Septate Junction ◽  
Cell Junctions ◽  
Salivary Gland Cell ◽  
Apical Cytoplasm

The salivary glands of 3rd or 4th instar larvae of Simulium niditifrons are about 5 mm long and up to 400 µ wide. They have a capacious lumen which is normally filled with secretion. The apical (luminal) plasmalemma of the gland cells is thrown into numerous microvilli. The basal plasmalemma is usually straight but is infolded in places. The infoldings may be complex near to cell junctions. There is a thick, uniform basement membrane. Contact surfaces of adjacent cells often interdigitate. A septate junction extends inwards from the lumen for one-quarter the depth of the cells. Rough endoplasmic reticulum is distributed evenly throughout the cytoplasm. Many Golgi complexes with dark membrane-bounded granules are scattered throughout the cytoplasm. Solitary granules, often more than I µ in diameter, lie in the apical cytoplasm, especially near the apical border of the cell. These granules resemble the larger Golgi granules and the contents of the lumen. Solitary granules consisting of 2 components have been seen in various stages of passage through the cell membrane. The 2 components are present in roughly constant proportions and can be identified in the larger Golgi granules and in the secretion in the lumen. The nucleus is spherical. The nuclear envelope is smooth in the larger cells of a gland but may be folded in the smaller cells. There are 80-100 pores/µ2 of nuclear envelope. Each pore appears to have a small granule at its centre. Microtubules, about 180 Å thick, are numerous in the apical cytoplasm, particularly near the luminal border. Tubules which lie deep in the cytoplasm are flanked by a clear area 100-200 Å wide. The fine structure of a salivary gland cell of Simulium appears to indicate that the major components of the salivary secretion are synthesized in association with the ribosomes on the rough endoplasmic reticulum, concentrated in the Golgi regions, formed into secretion granules, and passed out of the cell into the lumen of the gland by reverse phagocytosis.

The fine structure of fertilization in the fern Marsilea vestita

1978 ◽  
Vol 30 (1) ◽  
pp. 265-281
Author(s):  
D.G. Myles
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Nuclear Envelope ◽  
Plasma Membranes ◽  
Multilayered Structure ◽  
Thick Wall ◽  
Clear Space ◽  
Marsilea Vestita ◽  
Sperm Plasma Membrane ◽  
Sperm Penetration

The ultrastructural details of fertilization in the fern Marsilea vestita, including gamete approach and fusion, the fate of the spermatozoid organelles and the development of a possible block to polyspermy are described. The spermatozoid approaches the egg through layers of mucilage that surround the megaspores. It moves down the neck of the archegonium into the cavity above the egg. In order to reach the egg, it must move through a small hole in the thick wall that lies across the top of the egg. The fusion of the plasma membranes of the gametes results in an outflow of egg cytoplasm into the clear space under the sperm plasma membrane, creating a fertilization cone. All the organelles of the fertilizing spermatozoid, including nucleus, mitochondrion, microtubule ribbon, multilayered structure, and flagellar band, with approximately 150 flagella, enter the egg cytoplasm. The nucleus enters as a condensed rod of chromatin with no nuclear envelope. The chromatin begins to disperse immediately and a new nuclear envelope is formed around the chromatin by egg endoplasmic reticulum. The mitochondrion and the microtubules of the ribbon and flagella are broken down, but the fates of the flagellar band and the multilayered structure have not been determined. After spermatozoid penetration, a new extracellular layer appears above the surface of the egg, beginning in the region of sperm penetration and spreading across the top of the egg. This layer may be important in preventing other spermatozoids from fusing with the egg.

Fine structural changes in Eimeria tenella, from infections in chick embryos and chickens, after exposure to the anticoccidial drug robenidene

Parasitology ◽  
1972 ◽  
Vol 65 (2) ◽  
pp. 309-316 ◽  
Author(s):  
D. L. Lee ◽  
B. J. Millard
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Chick Embryo ◽  
Nuclear Envelope ◽  
Direct Effect ◽  
Protein Metabolism ◽  
Structural Changes ◽  
Eimeria Tenella ◽  
Metabolic Process ◽  
Chick Embryos

The structure of the various stages of Eimeria tenella grown in the chorioallantoic membranes of the chick embryo has been shown to be similar to the stages in the caecum of the bird. The effects of the anticoccidial drug, Robenidine, on the fine structure of the various stages of E. tenella, grown in the chick embryo and in the caecum of the bird, have been described. The first noticeable change occurs in the endoplasmic reticulum, including the nuclear envelope, and in the Golgi complexes of all stages. The nucleus itself, and the mitochondria, do not appear to be affected by the drug until much later, and this effect is probably due to the degeneration of the cell. It is suggested that the drug may have a direct effect upon protein metabolism of the parasite, resulting in swelling of the granular endoplasmic reticulum and Golgi complexes, or that it may have a primary effect upon some other organelle or metabolic process, and that the swelling of the endoplasmic reticulum and Golgi complexes is a secondary or tertiary phenomenon.

scholarly journals THE FINE STRUCTURAL LOCALIZATION OF GLUCOSE-6-PHOSPHATASE IN RAT LIVER

1962 ◽  
Vol 10 (6) ◽  
pp. 754-762 ◽  
Author(s):  
LOIS W. TICE ◽  
RUSSELL J. BARRNETT
Keyword(s):  
Endoplasmic Reticulum ◽  
Enzyme Activity ◽  
Plasma Membrane ◽  
Electron Microscope ◽  
Nuclear Envelope ◽  
Phosphatase Activity ◽  
Rat Liver ◽  
Structural Localization ◽  
Hepatic Cells ◽  
Fixed Material

Glucose-6-phosphatase activity was demonstrated histochemically in rat liver using either the Wachstein-Meisel medium or a modified Chiquoine medium, and the characteristic properties of the enzyme activity were confirmed. The distribution of activity in both unfixed and hydroxyadipaldehyde-fixed material was demonstrated with the electron microscope. Activity was found in both smooth- and rough-surfaced elements of the endoplasmic reticulum of hepatic cells, including the nuclear envelope, but was absent from the plasma membrane. These findings further implicate the endoplasmic reticulum as an organelle of transport, and in addition suggest that the nuclear envelope has functional as well as morphological continuity with the endoplasmic reticulum.

Compound Symbiosis in Peridinium Balticum

1973 ◽  
Vol 31 ◽  
pp. 500-501
Author(s):  
R. N. Tomas
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
The Other ◽  
Exact Nature ◽  
Symbiotic Relationship

Peridinium balticum appears to be unusual among the dinoflagellates in that it possesses two DNA-containing structures as determined by histochemical techniques. Ultrastructurally, the two dissimilar nuclei are contained within different protoplasts; one of the nuclei is characteristically dinophycean in nature, while the other is characteristically eucaryotic. The chloroplasts observed within P. balticum are intrinsic to an eucaryotic photosynthetic endosymbiont and not to the dinoflagellate. These organelles are surrounded by outpocketings of endoplasmic reticulum which are continuous with the eucaryotic nuclear envelope and are characterized by thylakoids composed of three apposed lamellae. Girdle lamellae and membranebounded interlamellar pyrenoids are also present. Only the plasmalemma of the endosymbiont segregates its protoplast from that of the dinophycean cytoplasm. The exact nature of this symbiotic relationship is at present not known.

Hepatic Ultrastructure Changes Induced by Lithocholic Acid

1967 ◽  
Vol 25 ◽  
pp. 162-163 ◽  
Author(s):  
F. G. Zaki
Keyword(s):  
Endoplasmic Reticulum ◽  
Lithocholic Acid ◽  
Smooth Endoplasmic Reticulum ◽  
Protein Diet ◽  
Low Protein Diet ◽  
Electron Microscopic ◽  
Hydropic Degeneration ◽  
Hepatic Cells ◽  
Low Protein ◽  
Microscopic Studies

Addition of lithocholic acid (LCA), a naturally occurring bile acid in mammals, to a low protein diet fed to rats induced marked inflammatory reaction in the hepatic cells followed by hydropic degeneration and ductular cell proliferation. These changes were accompanied by dilatation and hyperplasia of the common bile duct and formation of “gallstones”. All these changes were reversible when LCA was withdrawn from the low protein diet except for the hardened gallstones which persisted.Electron microscopic studies revealed marked alterations in the hepatic cells. Early changes included disorganization, fragmentation of the rough endoplasmic reticulum and detachment of its ribosomes. Free ribosomes, either singly or arranged in small clusters were frequently seen in most of the hepatic cells. Vesiculation of the smooth endoplasmic reticulum was often encountered as early as one week after the administration of LCA (Fig. 1).

Temporal and spatial interrelationships of confronting cisternae to nuclear envelope

1992 ◽  
Vol 50 (1) ◽  
pp. 930-931
Author(s):  
John R. Palisano
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Tumor Cells ◽  
Hela Cells ◽  
Microscopic Investigation ◽  
Electron Microscopic Investigation ◽  
Serial Sections ◽  
Electron Microscopic ◽  
Fetal Rat ◽  
Temporal And Spatial

Although confronting cistemae (CC) have been observed in a variety of tumor cells and normal fetal rat, mouse, and human epithelial tissues, little is known about their origin or role in mitotic cells. While several investigators have suggested that CC arise from nuclear envelope (NE) folding back on itself during prophase, others have suggested that CC arise when fragments of NE pair with endoplasmic reticulum. An electron microscopic investigation of 0.25 um thick serial sections was undertaken to examine the origin of CC in HeLa cells.

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