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Related to tissue: connective tissue, epithelial tissue


in biology, aggregation of cells that are similar in form and function and the intercellular substances produced by them. The fundamental tissues in animals are epithelial, nerve, connective, and muscle tissue; blood and lymph are commonly classed separately as vascular tissue. In the higher plants, there are four main types of tissue: (1) meristematic tissue (apical meristem and cambium), composed of cells that grow, divide, and differentiate into all the other cell types; (2) protective tissue (epidermis and cork), composed of thick-walled cells that cover roots, stem, and leaves; (3) fundamental tissues, consisting of cells that make up the bulk of the plant body, including parenchyma (thin-walled cells used for food storage), collenchyma (moderately thick-walled cells used for strength), and sclerenchyma (heavily thick-walled cells used for support in stems and roots); and (4) vascular tissue (xylem and phloem), specialized cells used for conduction. Organs are usually composed of several tissues. In many diseases there are apparent changes in tissue (see pathologypathology,
study of the cause of disease and the modifications in cellular function and changes in cellular structure produced in any cell, organ, or part of the body by disease. The changes in tissue include degeneration, atrophy, hypertrophy, hyperplasia, and inflammation.
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). Histologyhistology
, study of the groups of specialized cells called tissues that are found in most multicellular plants and animals. Histologists study the organization of tissues at all levels, from the whole organ down to the molecular components of cells.
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 is the study of the structure of tissues.


An aggregation of cells more or less similar morphologically and functionally. The animal body is composed of four primary tissues, namely, epithelium, connective tissue (including bone, cartilage, and blood), muscle, and nervous tissue. The process of differentiation and maturation of tissues is called histogenesis. See Histology



in biology, an aggregation of cells that are similar in origin, structure, and function. Tissues also include intercellular substances and structures that are products of cellular activity.

Animal tissues. Four types of animal tissues have been isolated, corresponding to the body’s principal somatic functions. Epithelial tissue comprises the skin and the membranes of the internal organs; its derivatives perform secretory functions and constitute, for example, the bulk of the liver and pancreas. Connective tissue, including that of the blood, performs nutritive and protective functions. Derivatives of connective tissue—cartilage and bone—comprise the supporting skeletal structure of vertebrates. Muscular tissue performs motor functions, moving the body and producing contractions of the organs. Nerve tissue regulates and coordinates the activity of all tissues, receives signals from the external environment, and determines the body’s respective reactions.

The development of each type of tissue is the result of a specific type of histogenesis occurring during the embryonal period. In many tissues, histogenesis continues in adult life, ensuring the regeneration and sometimes the growth of tissues. The functions specific to a given organ are usually performed by a single type of tissue, or by a number of specialized cells of that tissue. In all organs, different types of tissues interact to promote the nutritive and coordinative functions of the organ. The activity of tissue cells depends on their interrelationship within the tissue, as well as on outside hormonal and neural influences.

In lower organisms the tissues are not as distinctly differentiated as in higher ones. The evolution of organisms led to the specialization of cells and to the mutual interdependence of the cells’ functions and very existence within a system containing different types of tissues. However, by making a model of the cell environment, it is possible to keep cells alive outside the body and to develop tissues through tissue culture, which has become one of the principal methods of studying tissues. Histology is the study of animal tissues.


Plant tissues. The growth of a plant and the development of its internal structure depend on the activity of formative tissue, or meristem, whose derivatives undergo complex structural and functional differentiation when converting to elements of permanent tissues. The classification of permanent tissues is based on morphological, functional, and genetic features; an example is the distinction between parenchyma and prosenchyma. Permanent tissues belong to one of three systems: dermal, conductive, and fundamental (ground). In the ontogenesis of plants, these systems reflect the major stages in the internal differentiation of the plant during the process of evolution.

The most widely accepted physiological classification of plant tissues, that of G. Haberlandt, divides permanent tissues into a number of systems. These include the dermal system, composed of epidermis, cork, and cortex, and the mechanical system, composed of collenchyma (parenchyma cells with walls of irregular thickness) and sclerenchyma (lignified fibers and more or less iso-diametric sclereids). The absorptive system absorbs substances by means of rhizoids and root hairs made of epiblem. In Orchida-ceae, this function is performed by the multilayered epidermis (velamen) of the aerial roots. The assimilatory tissue system consists of parenchyma cells with many chloroplasts, and the conductive system consists of the xylem, which conducts water, and the phloem, which conducts the movement of organic matter. Further tissue systems are the storage system, consisting of parenchyma cells, the secretory system, which includes hydathodes, lati-cifers, and reservoirs for discharged substances, and the aeration system, consisting of intercellular spaces, stomata, and lenticels. All tissues except those of the dermal, conductive, and aeration systems are variants of fundamental (ground) tissue. Plant anatomy is the discipline that studies plant tissues.


Eames, A. J., and L. H. MacDaniels. Vvedenie v anatomiiu rastenii. Moscow-Leningrad, 1935. (Translated from English.)
Krasheninnikov, F. N. Lektsii po anatomii rastenii. Moscow-Leningrad, 1937.
Borodin, I. P. Kurs anatomii rastenii, 5th ed. Moscow-Leningrad, 1938.
Razdorskii, V. F. Anatomiia rastenii. Moscow, 1949.
Iatsenko-Khmelevskii, A. A. Kratkii kurs anatomii rastenii, Moscow, 1961.
Esau, K. Anatomiia rastenii. Moscow, 1969. (Translated from English.)



An aggregation of cells more or less similar morphologically and functionally.
A sheer woven fabric or gauze, usually of fine quality.


1. a part of an organism consisting of a large number of cells having a similar structure and function
2. a woven cloth, esp of a light gauzy nature, originally interwoven with threads of gold or silver
References in classic literature ?
You begin to see that it is a possible thing to transplant tissue from one part of an animal to another, or from one animal to another; to alter its chemical reactions and methods of growth; to modify the articulations of its limbs; and, indeed, to change it in its most intimate structure.
Then might I exemplify how an influence beyond our control lays its strong hand on every deed which we do, and weaves its consequences into an iron tissue of necessity.
A woman's voice was singing melodiously in another room of the palace, and with her voice was mingled the noise of a loom, at which she was probably seated, weaving a rich texture of cloth, and intertwining the high and low sweetness of her voice into a rich tissue of harmony.
She was habited in a gaudy tissue of scarlet cloth, trimmed with yellow silk, which, descending a little below the knees, exposed to view her bare legs, embellished with spiral tattooing, and somewhat resembling two miniature Trajan's columns.
But the tissue of perplexities, on account of this worthy individual, did not end here.
If a shaggy pauper had a right to bed and board and wages and a vote, women, of course, who were weaker than paupers, and whose physical tissue was in itself an appeal, should be maintained, sentimentally, at the public expense.
The safest plan is never to tread on a worm--not even on the last new subaltern from Home, with his buttons hardly out of their tissue paper, and the red of sappy English beef in his cheeks.
It was also the difference between living tissue of glowing loveliness with a divine breath, and a hard hollow figure of baked clay.
They are curtained within the recess, by a thick silver tissue adapted to the shape of the window, and hanging loosely in small volumes.
After all, the mediaeval belief in the Philosopher's Stone which could transmute metals, has its counterpart in the accepted theory of metabolism which changes living tissue.
What a tissue of mysteries and improbabilities the whole thing was
Why it was that upon this beautiful feminine tissue, sensitive as gossamer, and practically blank as snow as yet, there should have been traced such a coarse pattern as it was doomed to receive; why so often the coarse appropriates the finer thus, the wrong man the woman, the wrong woman the man, many thousand years of analytical philosophy have failed to explain to our sense of order.