Introduction to Cell Histology – Vocabulary Flashcards

82 vocabulary flashcards summarizing key histological terms, tissue-preparation steps, stain types, tissue categories and related pathology terminology from the lecture notes.

Histology

The study of cells and tissues and their microscopic structure.

Hematoxylin and Eosin (H&E) stain

The routine histological stain that colors basophilic structures blue-purple and acidophilic structures pink-red.

Hematoxylin

A basic, positively charged dye that binds negatively charged molecules (e.g., DNA, rRNA) making them blue-purple.

Eosin

An acidic, negatively charged dye that binds positively charged molecules (e.g., cytoplasmic proteins) staining them pink-red.

Basophilic structure

Cell or tissue component that carries a net negative charge and is stained by basic dyes such as hematoxylin.

Acidophilic structure

Cell or tissue component with a net positive charge that is stained by acidic dyes such as eosin.

Fixation (tissue prep)

The chemical step that inactivates enzymes and preserves tissue architecture, preventing autolysis.

Dehydration (tissue prep)

Removal of water from tissue via graded alcohols before embedding.

Clearing (tissue prep)

Replacement of alcohol with an organic solvent that is miscible with paraffin or plastic.

Infiltration (tissue prep)

Penetration of tissue with melted paraffin or plastic to harden it for sectioning.

Embedding (tissue prep)

Allowing infiltrated tissue to solidify in a mold, forming a block for sectioning.

Microtome

Instrument used to slice paraffin-embedded tissue into thin (1–10 µm) sections.

Sectioning artifact

Distortion such as folds, tears or ‘chatter’ introduced while cutting tissue sections.

Bright-field microscopy

Standard light microscopy in which contrast comes mainly from staining.

Phase-contrast microscopy

Optical technique that converts differences in refractive index to brightness, allowing visualization of unstained cells.

Differential interference microscopy

Light microscopy method creating pseudo-3D images of unstained specimens via interference patterns.

Epithelium

Avascular tissue composed of contiguous cells that line surfaces, cavities and form glands.

Connective tissue

Tissue with sparse cells, abundant extracellular matrix, and a supportive or binding function.

Muscle tissue

Contractile tissue (skeletal, cardiac, smooth) rich in actin and myosin that produces movement.

Nervous tissue

Tissue containing neurons and glia specialized to receive, transmit and integrate electrical information.

Basement membrane

Specialized extracellular layer (basal + reticular lamina) anchoring epithelium to underlying connective tissue.

Apical surface

The free, adluminal surface of an epithelial cell facing the lumen or external environment.

Basal surface

The side of an epithelial cell attached to the basement membrane; abluminal.

Adluminal

Oriented toward the lumen; synonymous with apical.

Abluminal

Directed away from the lumen; synonymous with basal.

Simple epithelium

Single layer of epithelial cells all in contact with the basement membrane.

Stratified epithelium

Multiple layers of epithelial cells; only basal cells contact the basement membrane.

Squamous cell

Flat, width > height epithelial cell with flattened nucleus.

Cuboidal cell

Approximately cube-shaped epithelial cell with round, central nucleus.

Columnar cell

Tall epithelial cell with height > width and oval nucleus near the base.

Mesothelium

Simple squamous epithelium lining closed body cavities (pleura, peritoneum, pericardium).

Endothelium

Simple squamous epithelium lining the luminal surface of blood and lymphatic vessels.

Glandular epithelium

Epithelial cells specialized for secretion forming exocrine or endocrine glands.

Exocrine gland

Gland that releases secretions onto a surface through a duct system.

Endocrine gland

Ductless gland that secretes hormones into the bloodstream.

Loose connective tissue

Connective tissue with loosely arranged collagen, abundant ground substance and numerous cells.

Dense connective tissue

Connective tissue with abundant collagen fibers and scant ground substance.

Dense irregular connective tissue

Dense CT with collagen bundles oriented haphazardly, resisting stress in multiple directions.

Dense regular connective tissue

Dense CT with parallel collagen bundles, providing tensile strength in one direction (e.g., tendon).

Collagen fibers

Thick eosinophilic extracellular fibers providing tensile strength; type I predominant in most CT.

Ground substance

Amorphous, hydrated extracellular material composed of proteoglycans and glycosaminoglycans.

Fibroblast

Principal resident cell of connective tissue that synthesizes collagen and ground substance.

Bone (as connective tissue)

Mineralized connective tissue with osteocytes in lacunae within a rigid matrix.

Cartilage

Avascular connective tissue with chondrocytes in lacunae and firm gel-like matrix.

Adipose tissue

Specialized connective tissue dominated by lipid-filled adipocytes; functions in storage and insulation.

Skeletal muscle

Voluntary, striated muscle with multinucleated fibers and peripheral nuclei.

Cardiac muscle

Involuntary, striated, branched muscle with single central nucleus and intercalated discs.

Smooth muscle

Involuntary, non-striated muscle of spindle-shaped cells each with one central nucleus.

Intercalated disc

Specialized junctional complex connecting cardiac muscle cells end-to-end for electrical coupling.

Neuron

Excitable cell with cell body, axon and dendrites that conducts electrical impulses.

Glial cell

Supportive nervous system cell that protects and nourishes neurons.

Nerve (axon bundle)

Collection of axons in the PNS surrounded by connective tissue sheaths.

Capsule (organ)

Connective-tissue layer that envelops an organ.

Cortex (organ)

Outer region of an organ, often containing specific functional tissue.

Medulla (organ)

Inner region of an organ lying deep to the cortex.

Parenchyma

The functional cellular component of an organ.

Stroma

The supportive or structural connective-tissue framework of an organ.

Metaplasia

Reversible replacement of one differentiated cell type with another.

Neoplasia

Uncontrolled, abnormal growth of cells forming a neoplasm (tumor).

Hyperplasia

Increase in the number of cells within a tissue or organ.

Hypertrophy

Increase in the size of individual cells, leading to enlarged tissue/organ.

Trichrome stain

Three-color stain (e.g., Mallory’s) that highlights collagen bright blue or green.

Periodic Acid–Schiff (PAS) stain

Reaction that stains polysaccharides (glycogen, mucin, basement membrane) magenta.

Weigert’s elastic stain

Histochemical stain that renders elastic fibers dark blue-black.

Silver stain

Impregnation method that colors reticular fibers, basement membranes or certain microbes black.

Golgi technique

Silver nitrate method that randomly stains entire neurons dark brown-black for morphological study.

Immunohistochemistry

Antibody-based staining technique used to detect specific proteins in tissue sections.

In situ hybridization (ISH)

Method that uses labeled nucleic acid probes to detect specific DNA or RNA sequences in tissue.

Fluorescence In Situ Hybridization (FISH)

Fluorescent ISH technique commonly used to visualize gene loci or chromosomal abnormalities.

Electron microscopy

High-resolution imaging using electron beams to visualize ultrastructural details (<1 µm sections).

Cytoskeleton

Network of microtubules, actin filaments and intermediate filaments providing cell shape and motility.

Rough endoplasmic reticulum (rER)

Basophilic organelle studded with ribosomes, site of protein synthesis.

Smooth endoplasmic reticulum (sER)

Non-staining organelle involved in lipid synthesis and detoxification; prominent in steroid-producing cells.

Secretory vesicles

Membrane-bound granules containing substances to be exocytosed; can be basophilic or eosinophilic.

Lipid droplet

Non-membranous inclusion appearing as an empty vacuole because lipids dissolve during processing.

Erythrocyte

Anucleate red blood cell that stains bright pink with eosin.

Mucosa

Combined layer of epithelium, basement membrane and loose CT (lamina propria) lining cavities.

Lamina propria

Loose connective tissue immediately deep to an epithelium within a mucosa.

Submucosa

Dense irregular connective tissue layer supporting the mucosa and housing larger vessels/nerve plexuses.

Muscularis mucosae / Tunica muscularis

Thin smooth muscle layer (or entire muscle coat) beneath submucosa that produces local movement.

Serosa

Outer covering of organs within body cavities consisting of simple squamous epithelium and CT.

Artifact (tissue prep)

Non-biological feature (fold, tear, precipitate) introduced during fixation, sectioning or staining.