Tissue

“ A tissue represents an aggregate of similar cells with the intercellular substances in relation with these as connective tissue, muscular tissue, etc. Where such cell aggregates are localized and where the cells are arranged in structures having definite form and size and performing a definite function, it is customary to designate such structures as organs, as the brain, liver, etc. ”

“ The next step was based on the observation that organs are composed of simpler parts called tissues. Often several different kinds of tissue will unite into one organ; for example, the heart is not all muscle but connective tissue and nerves enter into it; the walls of the stomach also contain glands, muscles, nerves, connective tissue, etc., all united to form the one organ—the stomach. The leaf of a plant is not all one kind of tissue, but several different kinds enter into it. We are thus approaching step by step the finer structure of living beings. ”

“ The body, as we have learned, is built up of certain elementary tissues which are combined to make bones, muscles, nerves, and other structures. The tissues, in turn, are made up of countless minute cells, each of which has its birth, lives its brief moment to do its work in the animal economy, is separated from the tissue of which it was a part, and is in due time eliminated by the organs of excretion,—the lungs, the skin, or the kidneys. ”

“ The bony palate of all mammals is covered with a closely-adhering layer of fibro-vascular tissue, the surface of which is protected by a coating of non-vascular epithelium, the former exactly corresponding to the derm or true skin, and the latter to the epiderm of the external surface of the body. ”

“ Of the Composition of the Tissues and of the Secretions in Health and Disease.—Having described thus individually the constituents of the tissues, we shall now present such results as have been hitherto obtained as to the quantitative composition of the organized tissues formed by their reunion, their secretory products and morbid alterations.
The skin of animals is a congeries of finely constructed organs, sensitive and secretory, imbedded in a peculiar tissue, which is one of those most yielding gelatine, whence the process of tanning skins. ”

“ The skin is remarkably complex in its structure, and is divided into two distinct layers, which may be readily separated: the deeper layer,—the true skin, dermis, or corium; and the superficial layer, or outer skin,—the epidermis, cuticle, or scarf skin.
The true skin consists of elastic and white fibrous tissue, the bundles of which interlace in every direction. Throughout this feltwork structure which gradually passes into areolar tissue are numerous muscular fibers, as about the hair-follicles and the oil glands. ”

“ The vegetable tissue will be transformed into the lowest organs of the animal; the cells into the mucous tissue, the intercellular passages into the lacteal vessels, the tracheæ, or spiral vessels, into the lowest kind of respiratory tubes or the cutaneo-lymphatic vessels. ”

“ Fatty Tissue, in anatomy, the adipose tissue, a tissue composed of minute cells or vesicles, having no communication with each other, but lying side by side in the meshes of the cellular tissue, which serves to hold them together, and through which also the blood-vessels find their way to them. ”

“ This epithelium consists really of a modification of the upper layer of the skin, and we see this modification familiarly in the difference between the skin of the face and the layer which is infolded to form the covering of the lips and the lining membrane of the mouth. No tissue is more familiar to the student of physiology than epithelium, composed as it is of epithelial cells or microscopic elements, which in one form or another are found in almost every important tissue of the body. ”

“ These tissues of mixed character form what is called connective tissue, which is found throughout the body.
Fat is deposited in little cells situated in the connective tissue.
Muscular tissue, which forms the great bulk of the body, is easily recognized by its ruddy color, and it constitutes what is known as “flesh.” It is fibrous, and if these fibers be examined under the microscope there will appear, in those under the influence of the will, transverse markings, while the muscles not under the will-power lack these markings. ”

“ The wall of the body in the Cœlentera has the same fundamental composition as among the higher animals, and exhibits various degrees of differentiation. [6] Inner and outer layers of epithelial tissue, splinted by connective tissue (in close relation with which we usually find muscular fibres) , are always developed. ”

“ All Living Tissue Plastic.—What is true of inanimate matter is doubly true of living tissue. The tissues of the human body can be molded into almost any form you choose if taken in time. A child may be placed on his feet at too early an age, and the bones of his legs form the habit of remaining bent. The Flathead Indian binds a board on the skull of his child, and its head forms the habit of remaining flat on the top. Wrong bodily postures produce curvature of the spine, and pernicious modes of dress deform the bones of the chest. ”

“ In the third class come tissues the cells of which have fused by their walls, but whose cell-cavities are not in continuity, such as osseous tissue and cartilage. In the tissues of the fourth class, comprising the most highly specialised of all, not only are the cell-walls continuous but also the cell-cavities ”

“ How, then, comes it, may the reflective mind repeat, that the grand Tissue of all Tissues, the only real Tissue, should have been quite overlooked by Science,—the vestural Tissue, namely, of woollen or other cloth; which Man's Soul wears as its outmost wrappage and overall; wherein his whole other Tissues are included and screened, his whole Faculties work, his whole Self lives, moves, and has its being? ”

“ Those important tissues with which the embalmer should be more or less acquainted are the following:
Skin, nails, hair, superficial fascia, deep fascia, lymphatics, glands, cartilage, bone, teeth, nerves, muscles, tendons, aponeuroses, ligaments, fat, mucous membranes, serous membranes, synovial membranes, arteries, veins and blood.
The Skin.
—The skin or integument (intego, to cover) is the outside covering of the human body. It is the first tissue that is cut when operating upon the body.
Fig. 2—A cross section of the skin. (Gray)
The skin is the seat of the organs of touch. ”

“ In the adult, the individuality of these cells is usually lost, since they are united to form membranes, tissues, and fibres. In nearly all animals the tissues thus built up from cells fall into four groups—epithelium, connective tissue, muscular tissue, and nervous tissue. ”

“ ORGANS INVOLVED IN FIRST STAGES OF DIGESTION
DIAGRAMS DISCLOSING HEART AND CONNECTIONS, RIBS AND LUNGS
(1) The Osseous, or bone tissue, is the framework of the body. This material is found, of course, in every part of the body and forms the skeleton.
(2) The Cartilaginous, or gristle, forms the joints of the body. This tissue covers the ends of the bones to form the joints; it unites the ribs with the breastbone; it forms the rings of the windpipe and the lid of the larynx at the back of the tongue; the lower part of the nose, the upper eyelid, and the ear. ”

“ We observe the structure of the skin—whether it be fine or coarse in its texture, whether it be hard and unyielding, or soft and elastic. We note the quantity of fat and of cellular tissue; and this enables us to form a judgment respecting the degree of embonpoint, and we have already abundantly proved that a man of a soft, lax habit, with an abundance of cellular and fatty tissues, differs in mental tendency and disposition from one of firm, tense fibre, in whom the bones, muscles, and articulations, are strong and prominent. ”

“ A skinlike tissue makes up [Pg 20] the lining of the stomach, while its outside is made of muscular tissue. The smallest parts of a tissue are little bodies named cells, and very fine threads called fibers.
Growth of the Body.—The body grows rapidly in childhood and more slowly after the sixteenth year, but it continues to get larger until about the twenty-fifth year of age. Some children always grow slowly, have weak bones, and frail bodies. This is generally so because they have poor food or do not chew it well, and get too little fresh air, sunshine, and sleep. ”

“ Throughout life, millions of these cells retain their primary characters, and constitute the white corpuscles of blood, "phagocytes," and connective tissue corpuscles; others again, engage in the formation of material round themselves, and lie, in such cases, as gristle and bone, embedded in the substance they have formed; others again, undergo great changes in form and internal structure, and become permanently modified into, for instance, nerve fibres and muscle substance. ”

“ All living structures, whether animal or vegetable, are built up of cells (which we shall consider in due course) , and these cells are grouped together for different purposes to form different tissues. The tissues are the different materials of which the body is made. There are eight principal tissues in the body: bone, gristle, muscle, nerve, skin, fat, fiber, and connecting tissue. ”

“ The whole of the body, at first, can be broken up into "cells," which become in one place metamorphosed into muscle,—in another place into gristle and bone,—in another place into fibrous tissue,—and in another into hair ”

“ The organs invariably derived, in the triploblastic forms, from the mesoblast, are the vascular and lymphatic systems, the muscular system, and the greater part of the connective tissue and the excretory and generative (?) systems. On the other hand, the nervous systems (with a few possible exceptions) and organs of sense, the epithelium of most glands, and a few exceptional connective-tissue organs, as for example the notochord, are developed from the two primary layers. ”

“ They are united with each other by a delicate layer of tissue, and constitute the rudiments of the neural and hæmal arches. In longitudinal sections of stage L special concentrated wedge-shaped masses of tissue are to be seen between the muscle-plates, which must not be confused with these rudiments. Immediately around the notochord the delicate investment of cells previously mentioned, is still present. ”

“ From long years of practical experience I have found that the special cells of each tissue will take up only those constituents which they need for the construction of their respective tissue, as taught by the law of chemotaxis. ”

“ Every tegument is periphery, just as there is nowhere a surface in the universe, which could have been produced according to the level or plane.
1864. All terrestrial processes, as digestion, respiration, and nutrition, are consequently tegumentary processes. All these organs must be tegumentary organs. Intestine, vessel, lung, in a word all viscera are naught but tegument.
1865. The vegetable tissue becomes in the animal, tegumentary tissue. The tegumentary formation is the vegetable in an animal—the parenchyma, the Visceral. ”

“ These parts are constantly being changed; every part is constantly growing, decaying, and being replaced during the life of the animal. The tissue is constantly replaced by new material; and if you go back to the young state of the tissue in the case of muscle, or in the case of skin, or any of the organs I have mentioned, you will find that they all come under the same condition. ”

“ These represent delicate structures which we call connective tissue fibrils, which have a mechanical function. By their tensile strength, their power to resist and pull, they give a certain supporting power to the tissues. Our picture represents one of the tissues which support and connect other portions of the body. ”

“ One of the elementary materials or fibres, having a uniform structure and a specialized function, of which ordinary animals and plants are composed; a texture; as, epithelial tissue; connective tissue.
The term tissue is also often applied in a wider sense to all the materials or elementary tissues, differing in structure and function, which go to make up an organ; as, vascular tissue, tegumentary tissue, etc.
4. Fig.: Web; texture; complicated fabrication; connected series; as, a tissue of forgeries, or of falsehood. ”

“ Connective tissue includes fibrous tissue, fatty tissue, cartilage and bone. The fibrous connective tissue is illustrated when the skin is easily picked up in folds. Fatty tissue occurs where large amounts of fat are deposited in the cells. Cartilage is found where a large amount of firm support is required. With muscle we are all familiar; it is the real lean meat of the body.
Blood and Lymph. —The blood is a fluid in which many cells are to be found. The fluid is known as serum or blood-plasma and the cells as corpuscles, and are both red and white. ”

“ The Connective, or cementing tissue, joins all the parts and cells of the body together. This substance is found everywhere, all over the body, and is like the mortar in a house, fastening all the bricks together. It is a sort of network of cells and long fibers. ”

“ They attack by preference the tissues derived from the mesoblastic layer of the embryo--the cellular tissue, bones, muscles, and viscera. They are often localised to one particular tissue or organ, such, for example, as the subcutaneous cellular tissue, the bones, or the liver, and they are rarely symmetrical. ”

“ The nucleus is manifest also in the tissue of the stigma, where in accordance with the compression of the utriculi, it has an intermediate form, being neither so much flattened as in the epidermis nor so convex as it is in the internal tissue of the column. ”