M1 – L2: Introduction to Histology

Vocabulary flashcards covering key histology terms from the lecture notes (M1-L2).

Gross anatomy

Study of organs and tissues visible to the naked eye.

Microanatomy

Study of microscopic tissues, cells, and cellular components.

Histology

Study of tissues; histo = tissue, -logy = study of.

Cytology

Study of cells and their components; cyto = cell.

Chemical level

Atoms and molecules; organelles are membrane-enclosed intracellular compartments with specific functions.

Organelles

Membrane-enclosed intracellular compartments with specific functions.

Cellular level

Level consisting of individual cells.

Tissue level

Level formed by a group of cells functioning together.

Organ level

Level of two or more tissues with specific functions.

Organ system level

Groups of related organs with a common function.

Organism level

The whole living being.

Epithelial tissue

Tissue on surfaces and in internal organs/cavities; forms glands; derived from germ layers.

Connective tissue

Cells and extracellular components providing protection and support; derived from mesoderm.

Muscle tissue

Contractile cells generating force and heat; derived from mesoderm.

Nervous tissue

Cells that detect stimuli and communicate via electrical signals; derived from ectoderm.

Germ layers

Ectoderm, endoderm, and mesoderm; primary tissue origins in the embryo.

Ectoderm

Germ layer giving rise to nervous system and skin, oral cavity and cornea

Endoderm

Germ layer giving rise to GI and respiratory tract, and urogenital tract

Mesoderm

Germ layer giving rise to connective tissue, muscle, and related structures.

Millimeter

Unit of length; 1 mm = 10^-3 m; structures visible to the naked eye around 0.2 mm.

Micrometer

µm; 1 µm = 10^-6 m; light microscopy can view structures as small as ~0.2 µm.

Nanometer

nm; 1 nm = 10^-9 m; electron microscopes can view ~2 nm.

Resolution

The smallest distance at which two points can be distinguished.

Magnification

Ability to magnify; ratio of image size to actual size (e.g., 10X, 100X).

Fixation

Chemical preservation of tissue using fixatives like formalin to preserve structure.

Dehydration

Removing water by passing tissue through increasing concentrations of alcohol.

Clearing

Removing alcohol and making tissue translucent with an organic solvent. Ex acetone

Infiltration

Tissue placed in melted paraffin to fill spaces after clearing.

Embedding

Paraffin is cooled and hardened to support tissue for sectioning.

Sectioning

Cutting tissue into thin slices (3–10 µm) with microtomes.

Staining

Applying dyes to color tissue for contrast.

Basophilic

Affinity for basic dyes; negatively charged components stain blue/purple.

Acidophilic

Affinity for acidic dyes; positively charged components stain red/pink.

Counterstaining

Using a second dye to highlight additional features alongside the primary stain.

Hematoxylin

Stains basophilic structures blue/purple.

Eosin

Stains acidophilic structures red/pink.

H&E

Hematoxylin and Eosin; the most commonly used histology stain.

Orcein

Stains elastic fibers.

Silver stain

Stains reticular fibers.

Trichrome stains

Stains collagen fibers (often used to distinguish muscle from connective tissue).

Osmic Acid

Stains lipids

PAS Stain

Stains carbs

Immunocytochemistry

Specific antibody based interactions

Light Microscope

Manipulate light with tissue components

What is used for embedding instead of paraffin in electron microscopy?

Plastic

TEM

Electron beam passes through tissue and can view components within a cell

SEM

Electron beam does not pass through tissue - views surface of cell

What are the different divisions of anatomy?

Gross anatomy, microanatomy, histology, cytology

Gastrulation

Formation of 3 germ layers on day 16

What are some examples of basophilic cell organelles?

Nucleus, ribosomes, rER

Acidophilic cell organelles?

mitochondria, collagen