scholarly journals CHONDROGENESIS, STUDIED WITH THE ELECTRON MICROSCOPE

1960 ◽  
Vol 8 (3) ◽  
pp. 719-760 ◽  
Author(s):  
Gabriel C. Godman ◽  
Keith R. Porter
Keyword(s):  
Golgi Apparatus ◽  
Ground Substance ◽  
Cell Cortex ◽  
Matrix Space ◽  
Cytoplasmic Inclusions ◽  
Structural Modifications ◽  
Fetal Rat ◽  
The Matrix ◽  
Connective Tissue Matrix ◽  
Tissue Matrix

The role of the cells in the fabrication of a connective tissue matrix, and the structural modifications which accompany cytodifferentiation have been investigated in developing epiphyseal cartilage of fetal rat by means of electron microscopy. Differentiation of the prechondral mesenchymal cells to chondroblasts is marked by the acquisition of an extensive endoplasmic reticulum, enlargement and concentration of the Golgi apparatus, the appearance of membrane-bounded cytoplasmic inclusions, and the formation of specialized foci of increased density in the cell cortex. These modifications are related to the secretion of the cartilage matrix. The matrix of young hyaline cartilage consists of groups of relatively short, straight, banded collagen fibrils of 10 to 20 mµ and a dense granular component embedded in an amorphous ground substance of moderate electron density. It is postulated that the first phase of fibrillogenesis takes place at the cell cortex in dense bands or striae within the ectoplasm subjacent to the cell membrane. These can be resolved into sheaves of "primary" fibrils of about 7 to 10 mµ. They are supposedly shed (by excortication) into the matrix space between the separating chondroblasts, where they may serve as "cores" of the definitive matrix fibrils. The diameter of the fibrils may subsequently increase up to threefold, presumably by incorporation of "soluble" or tropocollagen units from the ground substance. The chondroblast also discharges into the matrix the electrondense amorphous or granular contents of vesicles derived from the Golgi apparatus, and the mixed contents of large vacuoles or blebs bounded by distinctive double membranes. Small vesicles with amorphous homogeneous contents of moderate density are expelled in toto from the chondroblasts. In their subsequent evolution to chondrocytes, both nucleus and cytoplasm of the chondroblasts undergo striking condensation. Those moving toward the osteogenic plate accumulate increasingly large stores of glycogen. In the chondrocyte, the enlarged fused Golgi vesicles with dense contents, massed in the juxtanuclear zone, are the most prominent feature of the cytoplasm. Many of these make their way to the surface to discharge their contents. The hypertrophied chondrocytes of the epiphyseal plate ultimately yield up their entire contents to the matrix.

Strategies For Immunodissection Of The Connective Tissue Matrix And Basement Membranes

1999 ◽  
Vol 5 (S2) ◽  
pp. 1222-1223
Author(s):  
Douglas R. Keene ◽  
Sara F. Tufa
Keyword(s):  
Connective Tissue ◽  
Elastic Fiber ◽  
Dry Weight ◽  
Basement Membranes ◽  
The Matrix ◽  
Connective Tissue Matrix ◽  
Main Component ◽  
Tissue Matrix ◽  
And Task

Connective tissue matrices are quite diversified and include that composing skin, tendon, bone, cartilage, cornea and many others. The main component of the connective tissue matrix is collagen, composing approximately 70% of the dry weight of the human body. More members of the collagen family are discovered each year, with over twenty types described to date. Many of these collagens are tissue specific. In addition to the collagens, the connective tissue matrix is also the residence of epithelial and endothelial basement membranes and many other molecules including a variety of proteoglycans and elastic fiber components. The cells within the matrix are highly differentiated and task specific.Using immunocytochemical technique applied at the level of the electron microscope, we have focused our resources to understand the structure and functional role of these matrix molecules.

scholarly journals Evidence that contact with connective tissue matrix is required for normal interaction between Schwann cells and nerve fibers.

1978 ◽  
Vol 78 (3) ◽  
pp. 943-950 ◽  
Author(s):  
R P Bunge ◽  
M B Bunge
Keyword(s):  
Schwann Cell ◽  
Schwann Cells ◽  
Culture Medium ◽  
Nerve Fibers ◽  
Fetal Rat ◽  
Connective Tissue Matrix ◽  
Tissue Matrix ◽  
Dystrophic Mice ◽  
Rat Tail ◽  
Small Nerve

Explants of fetal rat sensory ganglia, cultured under conditions allowing axon and Schwann cell outgrowth in the absence of fibroblasts, occasionally develop nerve fascicles that are partially suspended in culture medium above the collagen substrate. In these suspended regions, fascicles are abnormal in that Schwann cells are decreased in number, are confined to occasional clusters along the fascicle, provide ensheathment for only a few axons at the fascicle periphery, and do not form myelin. When these fascicles are presented with a substrate of reconstituted rat-tail collagen, Schwann cell numbers increase, ensheathment of small nerve fibers occurs normally, and larger axons are myelinated. We conclude that, for normal development, Schwann cells require contact with extracellular matrix as well as axons. The Schwann cell abnormalities in suspended fascicles are similar to those observed in nerve roots of dystrophic mice.

Organisation in the Structure of the Cytoplasmic Ground Substance

1978 ◽  
Vol 36 (3) ◽  
pp. 627-639
Author(s):  
K.R. Porter
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Random Distribution ◽  
Ground Substance ◽  
The Matrix ◽  
Cell Processes ◽  
Cytoplasmic Ground Substance

Most types of cells are known from their structure and overall form to possess a characteristic organization. In some instances this is evident in the non-random disposition of organelles and such system subunits as cisternae of the endoplasmic reticulum or the Golgi complex. In others it appears in the distribution and orientation of cytoplasmic fibrils. And in yet others the organization finds expression in the non-random distribution and orientation of microtubules, especially as found in highly anisometric cells and cell processes. The impression is unavoidable that in none of these cases is the organization achieved without the involvement of the cytoplasmic ground substance (CGS) or matrix. This impression is based on the fact that a matrix is present and that in all instances these formed structures, whether membranelimited or filamentous, are suspended in it. In some well-known instances, as in arrays of microtubules which make up axonemes and axostyles, the matrix resolves itself into bridges (and spokes) between the microtubules, bridges which are in some cases very regularly disposed and uniform in size (Mcintosh, 1973; Bloodgood and Miller, 1974; Warner and Satir, 1974).

Long-Term Histologic Effects of Inferior Turbinate Laser Surgery

2001 ◽  
Vol 124 (4) ◽  
pp. 459-463 ◽  
Author(s):  
David B. Wexler ◽  
Gilead Berger ◽  
Ari Derowe ◽  
Dov Ophir
Keyword(s):  
Laser Treatment ◽  
Laser Surgery ◽  
Laser Energy ◽  
Inferior Turbinate ◽  
Surface Epithelium ◽  
Marked Diminution ◽  
Connective Tissue Matrix ◽  
Tissue Matrix ◽  
Histologic Changes

OBJECTIVE: In this study we sought to define the histologic changes produced by laser treatment of inferior turbinates. STUDY DESIGN: Eight inferior turbinates with prior laser treatment (mean, 26.8 months) were analyzed by light microscopy after turbinectomy for relief of refractory nasal obstruction. Histologic findings were compared with those of a group of 8 hypertrophic inferior turbinates that had no previous laser surgery. RESULTS: Laser-treated areas of the inferior turbinates demonstrated a histologically bland appearance, with marked diminution of seromucinous glands and relative preponderance of connective tissue matrix. Prominence of venous sinusoids was also significantly reduced in the laser-treated areas. Surface epithelium including goblet cells was reconstituted over the areas of laser application. CONCLUSION: Clinical laser surgery of the inferior turbinate produces striking long-term histologic changes. SIGNIFICANCE: The data suggest a differential response of turbinate histologic components to application of laser energy, with the glandular component being particularly sensitive. Further correlative study is needed to clarify the clinical significance of laser-induced histologic changes in inferior turbinates.

Memoirs: A Study of the Cytoplasmic Inclusions and Nucleolar Phenomena during the Oogenesis of the Mouse

1933 ◽  
Vol s2-75 (300) ◽  
pp. 697-721
Author(s):  
R.A. R. GRESSON
Keyword(s):  
Golgi Apparatus ◽  
Close Association ◽  
Large Body ◽  
Follicle Cell ◽  
Nuclear Body ◽  
Follicle Cells ◽  
Present Contribution ◽  
Cytoplasmic Inclusions ◽  
Golgi Bodies ◽  
Nucleolar Material

1. The Golgi apparatus of the germinal epithelium consists of a dark mass of material situated at one pole of the nucleus. The mitochondria occur scattered throughout the cytoplasm. 2. The Golgi material of the very early oocyte consists of rods and granules clumped together to form a large body at one pole of the nucleus; smaller masses of Golgi material may also be present. 3. In the young oocyte, surrounded by a follicle wall, a single juxta-nuclear body is present; at a later stage the individual Golgi elements break away from the juxta-nuclear body and become distributed throughout the ooplasm. 4. In the late oocytes the Golgi elements occur in close association with the mitochondrial clumps and also scattered through the ooplasm. In tubal eggs the Golgi bodies are smaller in size and more numerous than in the ovarian ova. 5. It is concluded that the large mitochondria of Lams and Doorme correspond to the oocyte Golgi elements of the present contribution. The behaviour of the Golgi material during the growth of the ovum resembles that of the eggs of other mammals. The present findings on the structure of the juxta-nuclear Golgi material agrees with Nihoul's account for the rabbit. 6. The mitochondria of the young oocytes occur scattered through the ooplasm, but are more numerous in the vicinity of the nucleus and Golgi material. Later, the majority of the mitochondria become collected into clumps; in the tubal eggs the mitochondrial clumps are more numerous. 7. The Golgi apparatus of young follicles is situated between the follicle-cell nucleus and the pole of the cell directed towards the oocyte; in follicles consisting of several layers the position of the Golgi apparatus varies, while in fully-formed follicles the Golgi material of many of the cells surrounding the follicular cavity are directed towards the cavity. This agrees with Henneguy's findings for the Golgi apparatus of the follicle-cells of the guinea-pig. The mitochondria of the follicle-cells occur scattered through the cytoplasm but are more numerous towards the pole of the cell adjoining the oocyte. 8. The number of nucleoli present in the early oocyte varies from one to five; the majority of the older oocytes contain a single nucleolus but two may be present. Extrusion into the ooplasm of nucleolar material takes place; the nucleoli and the nucleolar extrusions are basophil (Mann's methyl-blue eosin). 9. Fatty yolk is not present in the mouse ovum. It is suggested that the Golgi elements and mitochondria play some part in yolk-formation, and that some of the granules formed by the fragmentation of the nucleolar extrusions are added to the yolkglobules already present. The yolk-globules of unsegmented tubal eggs are situated towards one pole of the cell; at the twocell stage they appear to be evenly distributed between the two cells. 10. In degenerating eggs the mitochondria are clumped; the Golgi bodies occur in small groups or are closely applied to the mitochondrial clumps. In eggs which have undergone fragmentation the Golgi bodies occur in groups, while the majority of the mitochondria are clumped. The fat-globules, previously recorded by Kingery in degenerating eggs, were identified. In material treated by Ciaccio's method for the identification of fats, appearances suggest that the Golgi elements, and possibly the mitochondria, give rise to fat. Yolk-globules could not be distinguished in the late stages of these eggs.

Toward a kinetic theory of connective tissue micromechanics

1993 ◽  
Vol 74 (2) ◽  
pp. 665-681 ◽  
Author(s):  
S. M. Mijailovich ◽  
D. Stamenovic ◽  
J. J. Fredberg
Keyword(s):  
Connective Tissue ◽  
Three Dimensional ◽  
Elastic Fibers ◽  
Tissue Elasticity ◽  
Field Equations ◽  
Fiber Network ◽  
Rate Dependent ◽  
Connective Tissue Matrix ◽  
Tissue Matrix ◽  
And Diffusion

The aim of this study is to develop unifying concepts at the microstructural level to account for macroscopic connective tissue dynamics. We establish the hypothesis that rate-dependent and rate-independent dissipative stresses arise in the interaction among fibers in the connective tissue matrix. A quantitative theoretical analysis is specified in terms of geometry and material properties of connective tissue fibers and surrounding constituents. The analysis leads to the notion of slip and diffusion boundary layers, which become unifying concepts in understanding mechanisms that underlie connective tissue elasticity and energy dissipation during various types of loading. The complex three-dimensional fiber network is simplified to the interaction of two ideally elastic fibers that dissipate energy on slipping interface surfaces. The effects of such interactions are assumed to be expressed in the aggregate matrix. Special solutions of the field equations are obtained analytically, whereas the general solution of the model field equations is obtained numerically. The solutions lead to predictions of tissue behavior that are qualitatively, if not quantitatively, consistent with reports of a variety of dynamic moduli, their dependencies on the rate and amplitude of load application, and some features associated with preconditioning.

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