Introduction to Histology - Practice Flashcards

A set of 30 vocabulary-style flashcards covering the fundamental concepts of histology, microscopy, tissue preparation, and the classification of primary tissues.

Histology

The scientific study of the microscopic structure, chemical composition, and function of biological tissues.

Cytology

The scientific study of individual cells.

Gross Anatomy

The study of larger organs and systems visible to the naked eye.

Cross (Transverse) Sections

Tissue cuts made at right angles perpendicular to the long axis of a structure, producing a circular profile.

Longitudinal Sections

Tissue cuts made parallel to the long axis of a structure, resulting in elongated tracks or ribbons.

Oblique Sections

Tissue cuts made at any slanting angle between the horizontal and vertical axes, yielding complex oval or irregular shapes.

Light Microscope (LM)

An instrument using visible light transmitted through glass lenses with a practical resolution limit of roughly $0.2\,\mu m$.

Transmission Electron Microscopy (TEM)

A technique that passes electrons through ultra-thin tissue sections to achieve a resolution limit down to $0.1\,nm$.

Scanning Electron Microscopy (SEM)

A technique that bounces an electron beam off a metal-coated specimen to generate detailed 3D images of surface topology.

Fixation

The first step of slide preparation using chemical fixatives like $10\%$ neutral buffered formalin to preserve structural architecture and halt autolysis.

Dehydration

The removal of water from a specimen through an escalating series of graded ethanol baths ranging from $70\%$ to $100\%$ absolute alcohol.

Clearing

The substitution of alcohol with an organic agent, typically Xylene, to make the tissue translucent and miscible with paraffin wax.

Embedding

The process of submerging a cleared specimen in warm, liquid paraffin wax which hardens to provide structural support for cutting.

Microtome

A precision cutting instrument used to slice paraffin blocks into ultra-thin sections measuring between $3$ to $10\,\mu m$ thick.

Hematoxylin

A basic dye with a net positive charge that binds to acidic cellular targets, staining them deep blue or purple.

Basophilic

A term describing negatively charged, acidic cellular structures (like DNA and RNA) that have an affinity for basic dyes.

Eosin

An acidic dye with a net negative charge that binds to basic intracellular structures, staining them shades of pink to bright red.

Acidophilic (Eosinophilic)

A term describing positively charged, basic cellular structures (like cytoplasmic proteins and mitochondria) that have an affinity for acidic dyes.

Artifacts

Physical flaws or errors in a tissue slide caused by microtechnique steps, such as knife marks, tissue folds, or dehydration shrinkage gaps.

Structural Polarity

The organization of epithelial cells into defined domains, including an apical surface facing the environment and a basal surface anchored to the basement membrane.

Avascularity

The property of epithelial tissue having no direct blood vessels, relying on passive diffusion from underlying vascularized connective tissue.

Simple Epithelium

A classification of epithelium consisting of a single layer of cells optimized for quick diffusion, filtration, or absorption.

Stratified Epithelium

A classification of epithelium consisting of multiple layers of cells optimized to safeguard against mechanical abrasion and stress.

Ground Substance

A clear, amorphous, gel-like fluid rich in water, glycoproteins, and proteoglycans that fills the spaces between cells and fibers in the ECM.

Reticular Fibers

Highly branched, delicate nets of specialized collagen that form supporting scaffolds for soft organs like the liver and spleen.

Chondrocytes

Mature cartilage cells that are trapped in small cavities called lacunae.

Intercalated Discs

Dark-staining junctional blocks in cardiac muscle that provide structural adhesion and fast electrical coupling between cells.

Soma

The metabolic cell body of a neuron that houses the nucleus.

Dendrites

Short branching processes of a neuron designed to receive incoming signals.

Glial Cells (Neuroglia)

Non-conductive cells in nervous tissue that provide structural anchoring, metabolic nutrients, defense, and myelin insulation.