Histology of Connective Tissues Flashcards

A pathologist examining a biopsy from a torn Achilles tendon would primarily observe which histological feature?

Answer: Densely packed, parallel bundles of type I collagen fibers with flattened fibroblasts

Tendons connect muscle to bone and must withstand strong, unidirectional tensile forces. This function is served by dense regular connective tissue, which is characterized by densely packed, parallel arrays of type I collagen fibers. Flattened fibroblasts (tenocytes) are aligned between these fiber bundles.

In the stroma of a lymph node, which type of connective tissue forms a delicate, three-dimensional framework that supports the organ's cells, such as lymphocytes and macrophages?

Answer: Reticular connective tissue

Reticular connective tissue is composed of type III collagen fibers, also known as reticular fibers, which form a fine, branching network or 'stroma'. This mesh-like framework is ideal for supporting the cell populations within lymphoid organs like the spleen, liver, and lymph nodes.

A histology slide of the articular surface of the femur shows a smooth, glassy matrix with cells residing in small cavities (lacunae). This tissue is avascular and lacks a perichondrium. Which type of cartilage is being observed?

Answer: Hyaline cartilage

Hyaline cartilage is characterized by its smooth, glassy, and translucent matrix, which is rich in type II collagen fibrils that are not easily visible with standard staining. Chondrocytes are found within lacunae. It is the most common type of cartilage and is found on the articular surfaces of bones, where it provides a low-friction surface for joint movement.

Which resident cell of connective tissue proper is responsible for synthesizing the protein fibers and amorphous ground substance of the extracellular matrix?

Answer: Fibroblast

The fibroblast is the principal cell of connective tissue proper. Its primary function is to produce and maintain the extracellular matrix by secreting its components, including collagen, elastic, and reticular fibers, as well as the glycosaminoglycans and proteoglycans of the ground substance.

A student observes a tissue sample under a microscope that shows large, closely packed cells, each with a single, large lipid droplet that pushes the nucleus to the periphery, creating a 'signet ring' appearance. What is the primary function of this tissue?

Answer: Energy storage, insulation, and physical protection

The described histology is characteristic of unilocular (white) adipose tissue. The large cells, called adipocytes, are specialized for storing energy in the form of triglycerides within a single large lipid droplet. This tissue also serves to insulate the body and cushion organs.

Which of the following components of the extracellular matrix is a viscous, clear substance that fills the space between cells and fibers, and is composed primarily of glycosaminoglycans (GAGs), proteoglycans, and glycoproteins?

Answer: Ground substance

Ground substance is the amorphous, gel-like component of the extracellular matrix that surrounds the cells and fibers. It is highly hydrated and composed of proteoglycans, glycosaminoglycans (like hyaluronic acid), and multiadhesive glycoproteins, which allows it to act as both a lubricant and a barrier.