Animal Histology - Epithelial Tissues

Vocabulary flashcards covering the introductory concepts of Animal Histology, tissue classification, histogenesis, cell polarity, and simple covering epithelia.

Histology

The science that studies the microscopic structure of tissues.

Tissues

Sets of differentiated cells localized in one place that contribute to the same biological function, including cells and extracellular elements.

Histogenesis

The process by which tissues differentiate during embryonic development from the three primitive embryonic germ layers.

Ectoblast

The primitive embryonic germ layer that gives rise to part of the epithelial tissues (epidermis) and nervous tissue.

Mesoblast

The primitive embryonic germ layer that gives rise to non-specialized connective tissues, cartilage, bone, heart and vessel walls, and smooth and striated muscles.

Endoblast

The primitive embryonic germ layer that gives rise to the covering epithelium lining the intestine, respiratory system, and urogenital tract.

Epithelial Tissues

Tissues composed of closely juxtaposed, polarized cells with very narrow intercellular spaces resting on a basal membrane that separates them from connective tissue.

Covering Epithelia

Tissues formed by one or many layers of closely juxtaposed epithelial cells resting on a basal lamina, serving to cover inner or outer body surfaces.

Glandular Epithelia

Epithelial tissues with secretory function that are specifically involved in the elaboration of a secretory product.

Epidermis

The covering epithelium that coats the surface of the body (skin).

Mucosal Epithelium

The epithelium lining open natural internal cavities that extend the inside of the body to the outside, such as the airways, digestive, urinary, and genital tracts.

Endothelium

The simple squamous epithelium lining the cardiovascular cavities, including the heart and blood vessels.

Mesothelium

The simple squamous epithelium lining serous cavities, including pleural, peritoneal, and pericardial cavities.

Cytokeratins

Intermediate filaments present in the cytoplasm that are specific to epithelial cells.

Cell Polarity

The asymmetrical distribution of cytoplasm components and plasma membrane elements (proteins, enzymes, receptors) dividing an epithelial cell into distinct domains.

Apical Domain

The most specialized domain of an epithelial cell, in contact with the external environment or cavity lumen, containing specific functional proteins and specializations like microvilli or cilia.

Lateral Domain

The surface of an epithelial cell apposed to neighboring cells, containing anchoring, adhering, and tight junctions.

Basal Domain

The domain of an epithelial cell resting on the basal lamina, characterized by hemi-desmosomes and focal adhesion points.

Basement Membrane

A extracellular layer that participates in epithelial polarization, ensures cohesion with underlying connective tissue, and regulates exchange, filtration, and cellular metabolism.

Unistratified Epithelium

An epithelium composed of a single layer of cells of identical shape and size, specialized in selective diffusion, filtration, absorption, or secretion.

Classification of Epithelia

The categorization of covering epithelia according to three criteria: cell layer count, cell shape, and apical pole specializations.

Simple Squamous Epithelium

An epithelium formed by a thin layer of flattened cells with ovoid or elongated nuclei, involved in filtration, diffusion, and osmosis.

Simple Cuboidal Epithelium

An epithelium consisting of a single layer of cuboidal cells with a spherical central nucleus, specialized for secretion and absorption.

Simple Columnar Epithelium

An epithelium composed of elongated, cylindrical cells whose nuclei are all aligned in the basal region, involved in absorption and secretion.

Simple Columnar Non-Ciliated Epithelium

A simple columnar epithelium featuring apical microvilli forming a striated plateau or brush border, such as in the small intestine.

Simple Columnar Ciliated Epithelium

A simple columnar epithelium whose cells possess vibratile cilia at their apical pole, lining structures such as the fallopian tubes.