Electron-microscope observations on cell nuclei in various tissues of a teleost fish: the nucleolus-associated monolayer of chromatin structural units

1976 ◽  
Vol 21 (2) ◽  
pp. 315-327
Author(s):  
H.G. Davies ◽  
M.E. Haynes
Keyword(s):  
Electron Microscope ◽  
Connective Tissue ◽  
Nuclear Envelope ◽  
Teleost Fish ◽  
Base Sequence ◽  
Cell Nuclei ◽  
Structural Units ◽  
Thin Sections ◽  
Chromatin Structural ◽  
In Cells

Observations on stain uptake by thin sections through condensed interphase chromosomes in cells from epithelial and muscle tissue in kidney and intestine, and also in fibroblasts, show a distribution into DNA-rich and DNA-poor phases similar to that already described in cells from the connective tissue blood. In all the nuclei the nucleolus, when adjacent to the nuclear envelope, is separated from the inner membrane by a monolayer of chromatin structural units, similar to the monolayer enclosed on both sides by nuclear envelope, previously described in a wide variety of organisms. The data provide further support for the hypothesis that the condensed interphase chromosomes in eukaryotes are characterized by essentially similar structural units folded to form similar patterns. This hypothesis, regarding the higher order units, is consistent with data of others which show that histones and DNA fold to form similar repeating subunits in chromatin, irrespective of the base sequence in the DNA and the origin of the histones.

Light- and electron-microscope observations on certain leukocytes in a teleost fish and a comparison of the envelope-limited monolayers of chromatin structural units in different species

1975 ◽  
Vol 17 (3) ◽  
pp. 263-285
Author(s):  
H.G. Davies ◽  
M.E. Haynes
Keyword(s):  
Connective Tissue ◽  
Peripheral Blood ◽  
Teleost Fish ◽  
Constant Width ◽  
Cell Types ◽  
Convincing Evidence ◽  
Structural Units ◽  
Average Value ◽  
Chromatin Structural ◽  
Group B

Previously it was shown that the nuclear envelope-limited sheets of chromatin, monolayers of nucleoprotein structural units, are present in blood cells from 4 classes of vertebrates. Now we show that sheets of similar width are present in certain leukocytes of a fifth class, a teleost fish. We describe the fine structure of leukocytes in peripheral blood and in the main haematopoietic organ, kidney. We also examined the granulocytes of connective tissue in intestine. By May-Grunwald-Giemsa staining and electron microscopy heterophilic granulocytes, cosinophils but no basophils could be recognized in peripheral blood and kidney. Problems in classification of the cells are discussed. In one group (A) of 5 fish, sheets occurred at a frequency of roughly 1% in heterophilic (type 1) granulocytes and lymphocytes from peripheral blood. No sheets were found in a second group (B) of 5 fish. Kidney and intestine were examined in some fish from both groups and no sheets were present. In an atypical group (C) sheets were found in the eosinophilic (type 2) granulocytes from peripheral blood of one fish and in lymphocytes from connective tissue of intestine in another. Sheets were usually associated with nuclei of irregular shape and their width averaged 36 nm. We tabulate data from other workers on occurence and width of sheets. They are found in all the main classes of tissue in mammals, namely blood and other connective tissues, in epithelial, nervous, germinal tissue and muscle, as well as in invertebrate and certain plants. Their nearly constant width, average value 35 nm, provides very convincing evidence for the hypothesis that the molecules of DNA and protein are organized into the same fundamental structural units, irrespective of species. We discuss the variable incidence of sheets among different cell types and the factors which might determine this.

scholarly journals THE FIBROUS STRUCTURE OF THE NERVE AXON IN RELATION TO THE LOCALIZATION OF "NEUROTUBULES"

1950 ◽  
Vol 91 (5) ◽  
pp. 499-504 ◽  
Author(s):  
Francis O. Schmitt ◽  
Betty B. Geren
Keyword(s):  
Electron Microscope ◽  
Connective Tissue ◽  
Fibrous Structure ◽  
Thin Sections ◽  
Present Evidence ◽  
Nerve Axon ◽  
Connective Tissue Sheath ◽  
Formalin Fixed

In squid, frog, rat, and human nerves examined in thin sections with the electron microscope the axon contains, in addition to certain other particulates, characteristic filaments. These filaments have diameters ranging from about 100 to 200 Å and have indefinite length. They frequently have a nodose appearance due to the presence of discontinuities sometimes fairly regularly spaced along the filaments. This structure differs unmistakably from that of the dense-edged fibrils called "neurotubules" and it is clear that the latter are not axonic constituents. Though dense-edged fibrils can readily be demonstrated in fragmented formalin-fixed nerve preparations, they are seldom observed in thin sections. When such structures were seen in these experiments they were located in the connective tissue sheath. The present evidence offers no support for the view that "neurotubules" are structural entities of normal intact nerves.

scholarly journals ON THE FINE STRUCTURE AND COMPOSITION OF THE NUCLEAR ENVELOPE

1961 ◽  
Vol 11 (3) ◽  
pp. 559-570 ◽  
Author(s):  
R. W. Merriam
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Nuclear Envelope ◽  
Pore Structure ◽  
Potassium Permanganate ◽  
Osmium Tetroxide ◽  
Rana Pipiens ◽  
Total Density ◽  
Thin Sections ◽  
Whole Mounts

Nuclei from nearly ripe eggs of Rana pipiens were isolated and cleaned in 0.1 M KCl. The whole nucleus was then digested to various degrees with ribonuclease or trypsin, followed by washing and fixation in either osmium tetroxide or potassium permanganate. The nuclear envelope was dissected off, placed on a grid, air dried, and compared with undigested controls in the electron microscope. Some envelopes were dehydrated, embedded in methacrylate, and sectioned. Annuli around "pores" are composed of a substance or substances, at least partially fibrillar, which is preserved by osmium but lost during permanganate fixation. Material within the "pores" is also preserved by osmium but partially lost after permanganate. No evidence of granules or tubules in the annuli was found in air dried mounts although a granular appearance could be seen in tangentially oriented thin sections. Thin sections of isolated envelopes give evidence of diffuse material within the "pores" as well as a more condensed diaphragm across their waists. In whole mounts of the envelope the total density within "pores" is relatively constant from "pore" to "pore." All material within "pores," including the condensed diaphragm, is removable by trypsin digestion. Wispy material from the "pore" structure projects into the nucleus and annular material extends into the cytoplasm. Both annular and diaphragm materials remain with the envelope when it is isolated and are thus considered a part of its structure, not merely evidences of material passing through. There is no evidence of ribonuclease-removable material in any part of the "pore" complex.

Electron-Microscope Observations on the Organization of the Nucleus in Chicken Erythrocytes and a Superunit Thread Hypothesis for Chromosome Structure

1974 ◽  
Vol 16 (2) ◽  
pp. 261-299 ◽  
Author(s):  
H. G. DAVIES ◽  
A. B. MURRAY ◽  
M. E. WALMSLEY
Keyword(s):  
Electron Microscope ◽  
Central Element ◽  
Condensed Chromatin ◽  
Structural Units ◽  
Protein Ratio ◽  
Intact Cells ◽  
Thin Sections ◽  
Shell Forming ◽  
Chicken Erythrocytes ◽  
O Phase

Previously it was shown that when condensed chromatin from several different types of cell is stained with uranyl-lead and examined in thin sections in the electron microscope, the stain is distributed into a dot-dash pattern arising from threads, with lesser-staining intermediate areas. We now show that when a section through chicken erythrocyte chromatin is stained with ethanolic phosphotungstic acid (PTA) the stain distribution is homogeneous. This shows that the lesser-staining regions after uranyl-lead, cannot be an overlap artifact. We conclude that the stains and hence the molecules in chromatin are distributed between 2 phases, an o- and an e-phase, so called because the structural units in chromatin are arranged in an orderly way at the surface of the nucleus and give rise to oddly (o) and evenly (e) numbered bands. Measurements of electron density per unit thickness, proportional to the number of stain molecules per unit volume, are made in thin sections through erythrocytes and reticulocytes from adult hen, 4-day-old chicks and 17-day embryos. The results indicate differences in the packing of the molecules in chromatin and further show that the e-phase is quite likely to have a higher DNA to protein ratio than the o-phase. After uranyl-lead stain the visibility of the dot-dash pattern in cells from adult hen is relatively low due, we propose, to closer packing. In micrographs through condensed chromatin treated with uranyl-lead the eye selects out only the densely stained dots and dashes, width 17 nm. When erythrocyte chromatin is partially or completely disrupted in various ways, threads 25-30 nm then become visible. We propose that condensed chromatin in intact cells contains structural units which consist of a central element, width 17 nm previously referred to as the unit thread, forming the e-phase, surrounded by a cylindrical shell forming the o-phase. This socalled superunit thread is similar in width, about 25-30 nm, to that reported by other workers in preparations of chromosomes spread on water surfaces. The hypothesis therefore helps explain what appeared to be discrepancies in thread dimensions. Certain other ultrastructural features of erythrocyte nuclei are also reported which are either pertinent to the general aim of this study, namely the way in which nucleoproteins fold up in chromosomes, or to biochemical studies, to be reported shortly, in which attempts are made to locate the proteins removed from isolated erythrocyte nuclei during subsequent washing in salt solutions.

Electron-Microscope Observations on the Structure of Condensed Chromatin: Evidence for Orderly Arrays of Unit Threads on the Surface of Chicken Erythrocyte Nuclei

1970 ◽  
Vol 7 (1) ◽  
pp. 35-48
Author(s):  
A. C. EVERID ◽  
J. V. SMALL ◽  
H. G. DAVIES
Keyword(s):  
Nuclear Envelope ◽  
Sodium Citrate ◽  
Condensed Chromatin ◽  
Chicken Erythrocyte ◽  
Cell Nuclei ◽  
Structural Element ◽  
Thin Sections ◽  
Small Areas ◽  
The Common ◽  
Degree Of Order

A unit thread has been identified by electron microscopy as the common structural element in the condensed chromatin of a variety of cell nuclei. From the previous studies of thin sections normal to the nuclear envelope it was concluded that the unit thread, of diameter about 17 nm but varying somewhat depending on fixation, packed with spacings of about 28 nm on the surface of the nucleus to form one or more layers. Thin sections tangential to the nuclear envelope, described in this paper, reveal directly the degree of order within the surface layer; there are small areas or patches in which the units are regularly arranged. Units are also orderly arranged around the pores in the nuclear envelope. Unit threads are less easily visible in electron micrographs of mature erythrocytes than at earlier stages of development but the clarity with which they can be seen is increased by a brief treatment prior to fixation with sodium citrate.

Membranous alterations in the cytoplasm and nucleus in a primitive neuroectodermal tumor of the brain

1978 ◽  
Vol 36 (2) ◽  
pp. 628-629
Author(s):  
C. N. Sun ◽  
C. Araoz ◽  
H. J. White
Keyword(s):  
Nuclear Envelope ◽  
Tumor Cells ◽  
Osmium Tetroxide ◽  
Primitive Neuroectodermal Tumor ◽  
Uranyl Acetate ◽  
Neuroectodermal Tumor ◽  
Annulate Lamellae ◽  
Lead Citrate ◽  
Thin Sections ◽  
The Brain

The ultrastructure of a cerebral primitive neuroectodermal tumor has been reported previously. In the present case, we will present some unusual previously unreported membranous structures and alterations in the cytoplasm and nucleus of the tumor cells.Specimens were cut into small pieces about 1 mm3 and immediately fixed in 4% glutaraldehyde in phosphate buffer for two hours, then post-fixed in 1% buffered osmium tetroxide for one hour. After dehydration, tissues were embedded in Epon 812. Thin sections were stained with uranyl acetate and lead citrate.In the cytoplasm of the tumor cells, we found paired cisternae (Fig. 1) and annulate lamellae (Fig. 2) noting that the annulate lamellae were sometimes associated with the outer nuclear envelope (Fig. 3). These membranous structures have been reported in other tumor cells. In our case, mitochondrial to nuclear envelope fusions were often noted (Fig. 4). Although this phenomenon was reported in an oncocytoma, their frequency in the present study is quite striking.

Unusual Intranuclear Structures in Chick Sympathetic Neurons

1967 ◽  
Vol 25 ◽  
pp. 188-189
Author(s):  
E. B. Masurovsky ◽  
H. H. Benitez ◽  
M. R. Murray
Keyword(s):  
Electron Microscope ◽  
Sympathetic Neurons ◽  
Uranyl Acetate ◽  
Sympathetic Ganglia ◽  
Lead Citrate ◽  
Thin Sections ◽  
Cns Neurons ◽  
Mammalian Cns

Recent light- and electron microscope studies concerned with the effects of D2O on the development of chick sympathetic ganglia in long-term, organized culture revealed the presence of rod-like fibrillar formations, and associated granulofibrillar bodies, in the nuclei of control and deuterated neurons. Similar fibrillar formations have been reported in the nuclei of certain mammalian CNS neurons; however, related granulofibrillar bodies have not been previously described. Both kinds of intranuclear structures are observed in cultures fixed either in veronal acetate-buffered 2%OsO4 (pH 7. 4), or in 3.5% glutaraldehyde followed by post-osmication. Thin sections from such Epon-embedded cultures were stained with ethanolic uranyl acetate and basic lead citrate for viewing in the electron microscope.

Fine Structure of Interdental Cells in the Mouse Cochlea

1970 ◽  
Vol 28 ◽  
pp. 140-141
Author(s):  
Roberta M. Bruck
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Young Adult ◽  
Uranyl Acetate ◽  
Ground Substance ◽  
Tectorial Membrane ◽  
Lead Citrate ◽  
Unusual Structure ◽  
Thin Sections ◽  
Collagenous Fibers

An unusual structure in the cochlea is the spiral limbus; this periosteal tissue consists of stellate fibroblasts and collagenous fibers embedded in a translucent ground substance. The collagenous fibers are arranged in vertical columns (the auditory teeth of Haschke). Between the auditory teeth are interdental furrows in which the interdental cells are situated. These epithelial cells supposedly secrete the tectorial membrane.The fine structure of interdental cells in the rat was reported by Iurato (1962). Since the mouse appears to be different, a description of the fine structure of mouse interdental cells' is presented. Young adult C57BL/6J mice were perfused intervascularly with 1% paraformaldehyde/ 1.25% glutaraldehyde in .1M phosphate buffer (pH7.2-7.4). Intact cochlea were decalcified in .1M EDTA by the method of Baird (1967), postosmicated, dehydrated, and embedded in Araldite. Thin sections stained with uranyl acetate and lead citrate were examined in a Phillips EM-200 electron microscope.

SEM Examination of a Used Diamond Knife

1971 ◽  
Vol 29 ◽  
pp. 452-453
Author(s):  
J. Temple Black
Keyword(s):  
Electron Microscope ◽  
High Voltage ◽  
High Magnification ◽  
Metallic Materials ◽  
Wide Spread ◽  
Thin Sections ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Scanning Electron ◽  
Diamond Knife

Since its introduction by Fernandez-Moran, the diamond knife has gained wide spread usage as a common material for cutting of thin sections of biological and metallic materials into thin films for examination in the transmission electron microscope. With the development of high voltage E.M. and scanning transmission E.M., microtomy applications will become increasingly important in the preparation of specimens. For those who can afford it, the diamond knife will thus continue to be an important tool to accomplish this effort until a cheaper but equally strong and sharp tool is found to replace the diamond, glass not withstanding.In Figs. 1 thru 3, a first attempt was made to examine the edge of a used (β=45°) diamond knife by means of the scanning electron microscope. Because diamond is conductive, first examination was tried without any coating of the diamond. However, the contamination at the edge caused severe charging during imaging. Next, a thin layer of carbon was deposited but charging was still extensive at high magnification - high voltage settings. Finally, the knife was given a light coating of gold-palladium which eliminated the charging and allowed high magnification micrographs to be made with reasonable resolution.

Ultrastructure of Testicular Spermatozoon of the Fish Oreochromis Niloticus

1988 ◽  
Vol 46 ◽  
pp. 278-279
Author(s):  
T. Guha ◽  
A. Q. Siddiqui ◽  
P. F. Prentis
Keyword(s):  
Electron Microscope ◽  
Oreochromis Niloticus ◽  
Osmium Tetroxide ◽  
Sperm Cells ◽  
Adult Fish ◽  
Testicular Sperm ◽  
Thin Sections ◽  
Important Fish ◽  
Testicular Spermatozoon ◽  
Diamond Knife

Tilapia, Oreochromis niloticus, is an economically important fish in Saudi Arabia. Elucidation of reproductive biology of this species is necessary for successful breeding program. In this paper we describe fine structure of testicular sperm cells in O, niloticus.Testes from young adult fish were fixed in gluteraldehyde (2%) and osmium tetroxide (1%), both in cacodyl ate buffer. Specimens were processed in the conventional way for electron microscopy and thin sections of tissues (obtained by cutting the blocks with a diamond knife) were stained by ura- nyl acetate and lead citrate. These were examined in a Carl Zeiss electron microscope operated at 40 kV to 60 kV. Sperm cells were obtained from testes by squeezing them in cacodyl ate buffer. They were fixed in gluteraldehyde (2%) in the same buffer, air dried, gold coated and then examined in a Philips scanning electron microscope (SEM) operated at 25kV.The spermatozoon of O. niloticus is consisting of head, midpiece and tail (Fig. 1).

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