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Nerve & Muscle Tissue
What are the core concepts of histology?
Histology Topics for Lincoln Scholars Program

Every beginning biology student learns three fundamental concepts of cell biology:  All living things are made of cells.  All cells are fundamentally alike.  All cells come from pre-existing cells.  Together these three assertions comprise Cell Theory, one of the cornerstones of biology.

Cells are organized into tissues.  But far fewer students understand the fundamental organizing principles of tissue biology, the discipline known as "histology." 

Put most simply, our bodies are composed of four different kinds of stuff, traditionally regarded as the four basic tissue types

To elaborate a bit further, each of the four basic tissue types has its own distinctive character, a set of properties which unites all examples of that tissue type while distinguishing them from examples of the other three tissue types.  Practically every cell in the body belongs to one of these four tissue types (note caveat below).  Most organs include tissues of all four types.

The four basic tissue types are muscle tissue, nervous tissue, epithelial tissue, and connective tissue.

These, then, are the core concepts of histology:  Four basic tissue types, together with the characteristic properties of each type, muscle, nervous, epithelial, and connective.  To "unpack" these concepts in much greater detail, see basic tissue types or follow any of the links in the text above. 

Understanding how certain organs work -- notably the kidney and the lung and the liver -- requires some detailed knowledge of microanatomy that is unique to each organ; for example, podocytes and juxtaglomerular apparatus in the kidney, or interalveolar septa in the lung and bile canaliculi in the liver.  But only a tissue-level perspective can organize that knowledge and make it far easier to comprehend, by revealing how all three of these organs share with pancreas the same basic glandular tissue architecture, of epithelial parenchyma supported by connective tissue stroma

For a brief essay on how the four basic tissues are arranged in relation to one another to form organs, see "What are the most common patterns of tissue organization?"

For a much longer and more formal introduction to the basic concepts of histology, see "Basic tissue types."

Histology Topics for Lincoln Scholars Program

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CAVEAT:  Several of the generalizations above have peculiar exceptions.  A few of these exceptions are important; others are mainly curiosities.  Some of the more important exceptions are listed below.

Below are a few significant exceptions to the core-concept generalizations outlined above.

Comments and questions:

SIUC / School of Medicine / Anatomy / David King
Last updated:  4 September 2022 / dgk