Captions describe the image and the

view or magnification of the anatomy

or histology

Frontal section of stomach Anterior view

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Histology is the study of tissues, and

 tissues are the building materials of the body. Like the materials we use to make

the clothing we wear, tissues are the materials that form the various layers and

structures of all the body’s organs. For example, you might wear a light undershirt

of cotton beneath a silk long-sleeved shirt and wear a wool sweater over the top of

the two shirts. Each layer of clothing is made of a diff erent material, and the material

is organized into a unique structure that has its own functional qualities. Th e

same is true of the organs of the body. Each organ consists of distinct structural layers, and each layer is a specifi c type of tissue. For example, the

stomach has an inner lining of simple columnar epithelium that is in

contact with the food we eat and secretes enzymes to help digest the

food. Th is epithelial layer is surrounded by a vascular layer of loose

connective tissue that contains the blood vessels that transport the

 absorbed molecules from the stomach. Smooth muscle tissue surrounds the two inner layers and helps toss and turn the food within

the stomach and move it toward the small intestine. Th e smooth

muscle tissue is covered by a slippery, thin layer of simple squamous

epithelium that forms the outer surface of the stomach and allows it to

move against neighboring organs while reducing the damaging friction.

And just as the layers of clothing have names — undershirt, long-sleeved shirt,

sweater — so also do the structural layers of an organ such as the stomach — mucosa,

submucosa, muscularis, and serosa.

All the tissues of the body can be organized into four basic tissue categories — epithelial tissue, connective and supporting tissue, muscle tissue,

and nervous tissue. Each tissue category has unique structural features

that are shared by the tissues of that category. Epithelial tissues are

surface tissues that consist of numerous cells tightly packed together.

Connective and supporting tissues share the common feature of having relatively few cells that are scattered within a surrounding fi brous

extracellular matrix. Muscle tissue consists of elongated cells with specialized protein arrangements that are designed to shorten. Nervous tissue cells are branching, wire-like cells with a great variety of shapes and

lengths. In this chapter you will explore these four tissue categories and the

specifi c tissue types that comprise each category. In the chapters that follow, the

diff erent tissues will be observed in the context of the organs and organ systems they

form.

Find more information

about histology in

2 Histology

3

REAL ANATOMY

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closely packed cells of the epithelial tissues and contrast them with the scattered cells and the fi brous surrounding matrix

of the connective and supporting tissues. In the muscle tissue observe the long, slender specialized cells that are designed

to shorten, and in the nerve tissue the branched, wire-like cells. We will explore each of the principal tissue categories in

more detail on the pages that follow.

The facing pages show photomicrograph collages of the four principal tissue categories — epithelial

tissue, connective and supporting tissue, muscle tissue, and nervous tissue. The photomicrographs

illustrate the key structural features shared by the tissues in each category. Note the numerous

Tissues

Epithelial Tissues

Connective and Supporting Tissues

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Muscle Tissues

Nerve Tissues

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their cells and on the number of cell layers present. By combining the shape names — squamous (fl at cells), cuboidal, and

columnar — with the term simple if there is a single layer of cells or the term stratifi ed if there is more than one layer of cells,

almost all of the epithelial tissues can be described and named. The photomicrographs on this page and the facing page

represent the simple (single cell layer) epithelial tissues.

Epithelial tissues are surface tissues that consist of numerous cells, with

each cell forming membrane to membrane contact with its neighbors. As a

general rule, descriptions of epithelial tissues are based on the shape of

Epithelial Tissue

Simple squamous epithelium, mesothelium

Surface view of mesentery, 400x

Simple squamous epithelium, mesothelium

Section of mesentery, 400x

Simple squamous epithelium, endothelium

Section of capillary, 630x

Simple cuboidal epithelium

Urinary tubes in kidney - transverse section, 630x (left); longitudinal section, 400x (right)

 1 Nucleus

 2 Cytoplasm

 3 Cell membrane

 4 Capillary lumen

 5 Glandular lumen

 6 Connective tissue

 7 Mucous in goblet cell

 8 Microvilli

 9 Basement membrane

10 Blood vessel with red blood cells

 11 Cilia

12 Basal cell

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Simple columnar epithelium

Section of mucosa of small intestine, 630x

Pseudostratifi ed columnar epithelium

Section of mucosa of larynx, 400x

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The photomicrographs on this and the facing page illustrate the stratifi ed

(more than one layer of cells) epithelial tissues. Note that the tissues range

from two layers to numerous layers and the cell shape used for the tissue

name is the shape of the cells found in the surface layer.

Epithelial Tissue

Nonkeratinized stratifi ed squamous epithelium

Section of esophageal mucosa, 200x

Keratinized stratifi ed squamous epithelium

Section of skin, 200x

 1 Nucleus

 2 Cytoplasm

 3 Basal cell layer

 4 Intermediate cell layer

 5 Superficial cell layer

 6 Stratum basale

 7 Stratum spinosum

 8 Stratum granulosum

 9 Stratum lucidum

10 Stratum corneum

 11 Connective tissue

12 Basement membrane

13 Glandular lumen

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Stratifi ed cuboidal epithelium

Section of duct of esophageal gland, 400x

Stratifi ed columnar epithelium

Section of pharyngeal mucosa, 400x

Transitional epithelium

Section of urinary bladder mucosa, 400x

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and arrangement of the fi bers produced by the cells and secreted into the surrounding matrix. There are three named

fi bers in the matrix — collagen fi bers, reticular fi bers (actually a thin form of collagen), and elastic fi bers. The fi bers are

deposited in varying degrees of density and are arranged in different patterns. The tissue names are based on the different

fi ber types and patterns in the matrix.

Connective tissues have relatively few cells and the cells are surrounded by an extracellular matrix of fi bers, which the cells secrete.

The classifi cation and names of connective tissues arise from the type

Connective Tissue

Loose (areolar) connective tissue

Section of subcutaneous layer of integument, 400x

Adipose tissue

Section of epicardial fat, 200x

 1 Mast cell

 2 Fibroblast

 3 Collagen fiber

 4 Elastic fiber

 5 Reticular fiber

 6 Nucleus of adipose cell

 7 Cytoplasm

 8 Plasma membrane

 9 Lipid storage area

10 Nucleus of reticular cell

 11 Nucleus of fibroblast

12 Elastic lamella

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