Transport of thermal energy across the organization centre of chick embryo

The discovery of the organization centre of Amphibia by Spemann (1918) opened a new field in the outlook of experimental embryology; but there were several technical difficulties to be overcome in the application of the concept of the organizer to avian embryology. In this connexion the tissue culture technique has several advantages over the earlier methods of in situ sectioning or chorio-allantoic techniques, and it has helped a great deal in the understanding of the processes of development in the chick. It has already been proved that at least the anterior third of the primitive streak has an organizing function (Waddington, 1932); but regions outside the primitive streak have not been systematically tested so far for the inducing capacity. In the present studies an attempt is made to study the extent of the organization centre in the chick embryo at the definitive primitive streak stage.

Download Full-text

Otoconia formation in the chick embryo

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100076494 ◽

1983 ◽

Vol 41 ◽

pp. 572-573

Author(s):

C.D. Fermin ◽

M. Igarashi

Keyword(s):

Chick Embryo ◽

Inner Ear ◽

Gallus Domesticus ◽

The Body ◽

Abnormal Behavior ◽

Intensive Study ◽

Basic Fuchsin ◽

Gestational Period ◽

Sensory Epithelia ◽

Transmission Electron

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.

Download Full-text

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.

Download Full-text

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.

Download Full-text

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).

Download Full-text

Structural Studies on the Eukaryotic Ribosome

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100180033 ◽

1990 ◽

Vol 48 (1) ◽

pp. 256-257

Author(s):

Adriana Verschoor ◽

Ronald Milligan ◽

Suman Srivastava ◽

Joachim Frank

Keyword(s):

Chick Embryo ◽

3D Reconstruction ◽

Single Particle ◽

Mass Density ◽

Particle Surface ◽

Uranyl Acetate ◽

Electron Microscopic ◽

Eukaryotic Ribosome ◽

Negative Stain ◽

Reconstruction Methods

We have studied the eukaryotic ribosome from two vertebrate species (rabbit reticulocyte and chick embryo ribosomes) in several different electron microscopic preparations (Fig. 1a-d), and we have applied image processing methods to two of the types of images. Reticulocyte ribosomes were examined in both negative stain (0.5% uranyl acetate, in a double-carbon preparation) and frozen hydrated preparation as single-particle specimens. In addition, chick embryo ribosomes in tetrameric and crystalline assemblies in frozen hydrated preparation have been examined. 2D averaging, multivariate statistical analysis, and classification methods have been applied to the negatively stained single-particle micrographs and the frozen hydrated tetramer micrographs to obtain statistically well defined projection images of the ribosome (Fig. 2a,c). 3D reconstruction methods, the random conical reconstruction scheme and weighted back projection, were applied to the negative-stain data, and several closely related reconstructions were obtained. The principal 3D reconstruction (Fig. 2b), which has a resolution of 3.7 nm according to the differential phase residual criterion, can be compared to the images of individual ribosomes in a 2D tetramer average (Fig. 2c) at a similar resolution, and a good agreement of the general morphology and of many of the characteristic features is seen.Both data sets show the ribosome in roughly the same ’view’ or orientation, with respect to the adsorptive surface in the electron microscopic preparation, as judged by the agreement in both the projected form and the distribution of characteristic density features. The negative-stain reconstruction reveals details of the ribosome morphology; the 2D frozen-hydrated average provides projection information on the native mass-density distribution within the structure. The 40S subunit appears to have an elongate core of higher density, while the 60S subunit shows a more complex pattern of dense features, comprising a rather globular core, locally extending close to the particle surface.

Download Full-text