Histology: Connective Tissue

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Questions and Answers

What characterizes dense irregular connective tissue?

Fibers forming flat sheets

Fibers oriented in parallel bundles

Fibers interwoven in random orientation (correct)

Fibers loosely organized in a mesh

Which dye exhibits metachromasia when binding to the ground substance?

Toluidine blue (correct)

Eosin

Crystal violet

Hematoxylin

What are the fixed cells in loose connective tissue primarily responsible for?

Migrating to other tissues

Generating nerve impulses

Secreting ground substance (correct)

Producing hormones

Which statement about the ground substance is true?

It contains numerous polysaccharide chains. Signup and view all the answers

Which cell type is classified as a motile cell with a limited lifespan?

Macrophage Signup and view all the answers

What happens to the classification of the components of the ground substance as more is learned about their nature?

They are considered more complex than initially thought. Signup and view all the answers

What structural characteristic distinguishes dense regular connective tissue?

Fibers closely packed in parallel bundles Signup and view all the answers

What has contributed to the decline in the usage of the term acid mucopolysaccharides?

Advancements in chemical understanding Signup and view all the answers

What primarily holds the tissue fluid within the connective tissue matrix?

Glycosaminoglycans Signup and view all the answers

How are collagen fibers structured under the electron microscope?

They consist of parallel fibrils measuring 50-90 nm in diameter. Signup and view all the answers

What phenomenon occurs when fluid accumulation exceeds uptake in connective tissue?

Edema Signup and view all the answers

What characteristic do the smallest fibers exhibit under polarization microscopy?

Birefringence Signup and view all the answers

What is the diameter range of unit fibrils that compose collagen fibers?

50-90 nm Signup and view all the answers

What is a significant barrier to the spread of bacteria in connective tissue?

Presence of glycosaminoglycans Signup and view all the answers

How often do the transverse bands of collagen fibrils repeat along their length?

Every 67 nm Signup and view all the answers

Which method is commonly used to visualize collagen fibers in unstained preparations?

Polarizing microscopy Signup and view all the answers

Which glycosaminoglycan is known for its high viscosity in aqueous solutions?

Hyaluronic acid Signup and view all the answers

What is the approximate length of each collagen molecule within the unit fibrils?

300 nm Signup and view all the answers

What technique improves the preservation of glycosaminoglycans in electron microscopy preparations?

Incorporating a polycationic dye Signup and view all the answers

What is the length of a typical hyaluronic acid molecule composed of approximately 5000 disaccharides?

2.5 μm Signup and view all the answers

Which staining method is used to identify glycosaminoglycans due to their anionic properties?

Cationic dye staining Signup and view all the answers

What type of structure do glycosaminoglycans form when dehydrated?

Granules of 10-20 nm Signup and view all the answers

What is the primary mechanism through which invasive bacteria can damage hyaluronic acid?

Production of hyaluronidase enzyme Signup and view all the answers

What helps glycosaminoglycans interact favorably in preservation techniques?

Binding with anionic groups Signup and view all the answers

What is the primary structural characteristic of collagen fibers as described?

They appear as random oriented in loose connective tissue. Signup and view all the answers

Which staining method results in collagen fibers appearing blue?

Masson's trichrome stain Signup and view all the answers

What is the molecular weight of each a-chain in collagen?

100,000 Signup and view all the answers

What holds the a-chains together within the collagen triple helix?

Hydrogen bonds Signup and view all the answers

What happens to collagen molecules when warmed to body temperature in vitro?

They spontaneously polymerize to form cross-striated fibrils. Signup and view all the answers

What is the characteristic pattern observed in the unit fibrils of collagen under an electron microscope?

Cross-striations indicating periodicity Signup and view all the answers

What span distance is mentioned for each turn in the right-handed triple helix of collagen?

8 nm Signup and view all the answers

What results in the appearance of dark bands in collagen fibrils during contrast microscopy?

Absence of stain in the overlapping regions Signup and view all the answers

What is the primary origin of connective tissues in the body?

Mesoderm Signup and view all the answers

Which connective tissue is primarily specialized for energy storage?

Adipose tissue Signup and view all the answers

What role does loose connective tissue play in the body?

Supports organ parenchyma Signup and view all the answers

What is the primary component of the extracellular matrix in connective tissues?

Ground substance Signup and view all the answers

How does the nature of the extracellular matrix vary in different regions of connective tissue?

It varies according to the abundance of cells, fibers, and ground substance Signup and view all the answers

What is predominantly found in the ground substance of connective tissue?

Hydrated gel Signup and view all the answers

What mechanism is essential for the interaction between epithelial cells and connective tissue?

Ground substance dynamics Signup and view all the answers

What describes the extracellular matrix in dense connective tissue compared to loose connective tissue?

Very abundant and densely packed fibers Signup and view all the answers

Study Notes

Overview of Connective Tissue

Connective tissues originate from embryonic mesenchyme and encompass a diverse group of structures.
Cartilage and bone provide firm support due to specialized extracellular matrices.
Adipose tissue functions primarily as lipid storage for energy.

Functions of Connective Tissue

Provides cohesion among structural elements in the body.
Serves as a medium for blood vessel distribution, nourishing organs, and facilitating waste elimination.
The organization and composition of connective tissue varies across different regions.

Ground Substance

Composed of a hydrated gel where cells and fibers are embedded; known as ground substance.
Acts as the medium for nutrient and waste exchange between blood and organs.
Staining properties include metachromasia and reaction to specific dyes like toluidine blue and periodic-acid-Schiff (PAS).

Cell Types in Connective Tissue

Two categories: fixed cells (stable, long-lived fibroblasts) and free cells (motile, short-lived).
Fixed cells produce and maintain the extracellular matrix, while free cells migrate from blood and participate in defense.

Glycosaminoglycans

Major components include chondroitin sulfate, keratan sulfate, heparan sulfate, and hyaluronic acid.
Hyaluronic acid contributes to the gel-like consistency of the ground substance and is found in joint fluid and the vitreous humor of the eye.
High viscosity helps protect against bacterial invasion.

Fluid Dynamics

Tissue fluid is primarily held by hydrophilic glycosaminoglycans; smaller molecules can still diffuse through.
Edema occurs when fluid accumulation surpasses the normal absorption capacity of venous ends.

Collagen Fibers

Present in all types of connective tissue, varying in diameter (0.5-10 μm) and anatomical arrangement (randomly oriented in loose connective tissue).
Composed of unit fibrils (50-90 nm in diameter), which are polymers made from three polypeptide chains (α-chains) intertwined in a triple helix structure.
Characterized by a repeating striation pattern of 67 nm along the fibril length, visible under electron microscopy and through selective staining.

Preparation Techniques for Study

Various techniques improve preservation and visualization of connective tissue components, including high-pressure freezing and collation of specific dyes for electron microscopy.
Routine histological methods might not fully preserve ground substance, but glycerol or other cationic dyes can highlight glycosaminoglycans.

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Description

This quiz covers the various types, functions, and composition of connective tissue, focusing on its origin from embryonic mesenchyme. Learn about the roles of cartilage, bone, and adipose tissue, as well as the importance of ground substance and different cell types in connective tissue. Test your understanding of key concepts related to connective tissue.