Optical mapping with multiple-site recording reveals the functional organization of the trigeminal nuclei in the chick embryo

Otoconia are microscopic geometric structures that cover the sensory epithelia of the utricle and saccule (gravitational receptors) of mammals, and the lagena macula of birds. The importance of otoconia for maintanance of the body balance is evidenced by the abnormal behavior of species with genetic defects of otolith. Although a few reports have dealt with otoconia formation, some basic questions remain unanswered. The chick embryo is desirable for studying otoconial formation because its inner ear structures are easily accessible, and its gestational period is short (21 days of incubation).The results described here are part of an intensive study intended to examine the morphogenesis of the otoconia in the chick embryo (Gallus- domesticus) inner ear. We used chick embryos from the 4th day of incubation until hatching, and examined the specimens with light (LM) and transmission electron microscopy (TEM). The embryos were decapitated, and fixed by immersion with 3% cold glutaraldehyde. The ears and their parts were dissected out under the microscope; no decalcification was used. For LM, the ears were embedded in JB-4 plastic, cut serially at 5 micra and stained with 0.2% toluidine blue and 0.1% basic fuchsin in 25% alcohol.

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Morphological Examination of a Herpes-type Virus Indigenous for Tree Shrews

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100067790 ◽

1970 ◽

Vol 28 ◽

pp. 160-161

Author(s):

J. P. Brunschwig ◽

R. M. McCombs ◽

R. Mirkovic ◽

M. Benyesh-Melnick

Keyword(s):

Electron Microscopy ◽

Soft Tissue ◽

Chick Embryo ◽

Soft Tissue Sarcoma ◽

Cell Cultures ◽

Tree Shrew ◽

Type Virus ◽

Morphological Examination ◽

Tree Shrews ◽

Embryo Cells

A new virus, established as a member of the herpesvirus group by electron microscopy, was isolated from spontaneously degenerating cell cultures derived from the kidneys and lungs of two normal tree shrews. The virus was found to replicate best in cells derived from the homologous species. The cells used were a tree shrew cell line, T-23, which was derived from a spontaneous soft tissue sarcoma. The virus did not multiply or did so poorly for a limited number of passages in human, monkey, rodent, rabbit or chick embryo cells. In the T-23 cells, the virus behaved as members of the subgroup B of herpesvirus, in that the virus remained primarily cell associated.

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Scanning electron microscopic study of collagen fibrillogenesis and extracellular compartmentalization in the chick embryo tendon

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100142669 ◽

1986 ◽

Vol 44 ◽

pp. 208-209

Author(s):

Grace C.H. Yang

Keyword(s):

Chick Embryo ◽

Extracellular Space ◽

Fibroblast Cell ◽

Collagen Fibrils ◽

Electron Microscopic ◽

Voltage Electron ◽

Scanning Electron Microscopic Study ◽

Microscopic Studies ◽

And Function

The size and organization of collagen fibrils in the extracellular matrix is an important determinant of tissue structure and function. The synthesis and deposition of collagen involves multiple steps which begin within the cell and continue in the extracellular space. High-voltage electron microscopic studies of the chick embryo cornea and tendon suggested that the extracellular space is compartmentalized by the fibroblasts for the regulation of collagen fibril, bundle, and tissue specific macroaggregate formation. The purpose of this study is to gather direct evidence regarding the association of the fibroblast cell surface with newly formed collagen fibrils, and to define the role of the fibroblast in the control and the precise positioning of collagen fibrils, bundles, and macroaggregates during chick tendon development.

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Organization of transcription and pre-mRNA splicing within the mammalian cell nucleus

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010014021x ◽

1995 ◽

Vol 53 ◽

pp. 768-769

Author(s):

D.L. Spector ◽

S. Huang ◽

S. Kaurin

Keyword(s):

Rna Polymerase Ii ◽

Cell Nucleus ◽

Functional Organization ◽

Mrna Splicing ◽

Splicing Factors ◽

Interchromatin Granule Clusters ◽

Interchromatin Granule ◽

Nuclear Regions ◽

Relationship Of ◽

Perichromatin Fibrils

We have been interested in the organization of RNA polymerase II transcription and pre-mRNA splicing within the cell nucleus. Several models have been proposed for the functional organization of RNA within the eukaryotic nucleus and for the relationship of this organization to the distribution of pre-mRNA splicing factors. One model suggests that RNAs which must be spliced are capable of recruiting splicing factors to the sites of transcription from storage and/or reassembly sites. When one examines the organization of splicing factors in the nucleus in comparison to the sites of chromatin it is clear that splicing factors are not localized in coincidence with heterochromatin (Fig. 1). Instead, they are distributed in a speckled pattern which is composed of both perichromatin fibrils and interchromatin granule clusters. The perichromatin fibrils are distributed on the periphery of heterochromatin and on the periphery of interchromatin granule clusters as well as being diffusely distributed throughout the nucleoplasm. These nuclear regions have been previously shown to represent initial sites of incorporation of 3H-uridine.

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Immunolocalization of nuclear antigens in cryofixed cells which have been prepared by molecular distillation drying or freeze-substitution

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100162053 ◽

1990 ◽

Vol 48 (3) ◽

pp. 898-899

Author(s):

David L. Spector ◽

Robert J. Derby

Keyword(s):

Cell Nucleus ◽

Molecular Distillation ◽

Functional Organization ◽

Freeze Substitution ◽

3 Dimensional ◽

Small Nuclear Ribonucleoprotein ◽

Nuclear Antigens ◽

Dimensional Reconstruction ◽

Nuclear Regions ◽

Immunoperoxidase Labeling

Studies in our laboratory are involved in evaluating the structural and functional organization of the mammalian cell nucleus. Since several major classes (U1, U2, U4/U6, U5) of small nuclear ribonucleoprotein particles (snRNPs) play a crucial role in the processing of pre-mRNA molecules, we have been interested in the localization of these particles within the cell nucleus. Using pre-embedding immunoperoxidase labeling combined with 3-dimensional reconstruction, we have recently shown that nuclear regions enriched in snRNPs form a reticular network within the nucleoplasm which extends between the nucleolar surface and the nuclear envelope. In the present study we were inte rested in extending these nuclear localizations using cell preparation techniques which avoid slow penetration of fixatives, chemical crosslinking of potential antigens and solvent extraction. CHOC 400 cells were cryofixed using a CF 100 ultra rapid cooling device (LifeCell Corp.). After cryofixation cells were molecular distillation dried, vapor osmicated, in filtra ted in 100% Spurr resin in vacuo and polymerized in molds a t 60°C. Using this procedure we were able to evaluate the distribution of snRNPs in resin embedded cells which had not been chemically fixed, incubated in cryoprotectants or extracted with solvents.

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vitreal cells and specialized phagocytes in the chick embryo retina: A TEM and SEM study

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100159205 ◽

1990 ◽

Vol 48 (3) ◽

pp. 330-331

Author(s):

M.A. Cuadros ◽

M.J. Martinez-Guerrero ◽

A. Rios

Keyword(s):

Cell Death ◽

Plasma Membrane ◽

Acid Phosphatase ◽

Chick Embryo ◽

Basement Membrane ◽

Sem Images ◽

Intimate Contact ◽

Cellular Processes ◽

Sem Study ◽

Free Cells

In the chick embryo retina (days 3-4 of incubation), coinciding with an increase in cell death, specialized phagocytes characterized by intense acid phosphatase activity have been described. In these preparations, all free cells in the vitreal humor (vitreal cells) were strongly labeled. Conventional TEM and SEM techniques were used to characterize them and attempt to determine their relationship with retinal phagocytes.Two types of vitreal cells were distinguished. The first are located at some distance from the basement membrane of the neuroepithelium, and are rounded, with numerous vacuoles and thin cytoplasmic prolongations. Images of exo- and or endocytosis were frequent; the cells showed a well-developed Golgi apparatus (Fig. 1) In SEM images, the cells was covered with short cellular processes (Fig. 3). Cells lying parallel to or alongside the basement membrane are elongated. The plasma membrane is frequently in intimate contact with the basement membrane. These cells have generally a large cytoplasmic expansion (Fig. 5).

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