Page images
PDF
EPUB

loplaxes; nucleated red blood-cells, the forerunners of the erythrocytes; rounded cells, whose protoplasm contains hemoglobin, the nuclei being small and dense; eosinophile cells and red blood-corpuscles.

The venous capillaries of the bone-marrow are wide, and have sieve-like openings in the walls, like the splenic lacunæ.

The yellow marrow consists only of connective tissue and fat; it develops by fatty changes in the red marrow in postfetal life.

The so-called gelatinous marrow is found in emaciated and cachectic individuals, and is the result of fat atrophy in the yellow marrow.

Focal necrosis of the bone-marrow occurs in certain infectious diseases, especially in variola, typhus, and typhoid fever.

The bone-marrow presents quite a characteristic appearance in those diseases that produce changes in the serum and the cells of the blood, such as pernicious anemia and leukemia. In pernicious anemia the yellow marrow of the long bones changes to red marrow, which contains all the elements normally found in this sort of marrow, such as marrow-cells, giant cells, eosinophilous cells, and nucleated red corpuscles. The last, as well as nonnucleated, red corpuscles, may assume a remarkably large size (macroerythrocytes, Ehrlich); some may contain two or more small, dense nuclei. In addition, there are usually found numerous cells containing blood-corpuscles; these cells are presumably marrow-cells, filled with red blood-corpuscles, which have undergone disintegration and have been taken up by the phagocytic cells. The fat-tissue is usually reduced to a minimum.

In leukemia yellow marrow is also commonly changed to grayish-red or red; in the most advanced stages it becomes soft and puriform, as in the myelogenic form of leukemia, in which this change in the marrow is regarded

5

as a primary condition. The reticulum contains marrowcells in large numbers—that is, large, round cells with a narrow, protoplasmic ring and large, lightly stained, round or oval nuclei, from which the smaller and dark nuclei of the lymphocytes are sharply differentiated. In this form the blood is also loaded with myelocytes. The fat-tissue may be crowded out completely.

The infectious processes in the bone-marrow, as suppurative and tuberculous osteomyelitis, are considered in connection with diseases of the bones.

II. RESPIRATORY ORGANS.

THE NOSE.

The mucous membrane of the nose is lined with a single layer of ciliated epithelium, except in that part of its cavity known as the auricle, which is covered by stratified, flat epithelium. Under the epithelial covering is a stratum proprium, richly infiltrated with leukocytes. The epithelium of the olfactory region carries the special olfactory cells, peculiarly transformed ganglion cells,— which communicate with the olfactory lobes by means of nerve-fibers that originate at the base of the cells. The stratum proprium also contains alveolar glands. The loose submucous tissue supports a well-developed plexus of veins.

One of the most frequent pathologic processes in the nasal mucous membrane is the so-called nasal catarrh, or coryza. Histologically, this is characterized by great hyperemia, edema, and increased secretion of the glands, so that many of their cells are converted into goblet cells. Goblet cells also appear among the ciliated surface cells. The leukocytes of the stratum proprium are increased; they penetrate the epithelium and become mixed with the secretion, which, in proportion to the number of cells, assumes a more or less well-marked purulent character. Desquamated epithelial cells also become mixed with the secretion, which, furthermore, contains bacteria among which diplococci and Friedländer's pneumobacillus predominate; staphylococci are also met with.

Should the catarrh become chronic under the influence of long-continued, injurious agencies, then the mucous membrane becomes thicker than normal on account of the extensive development of the veins and of the increase of tissue in the stratum proprium. The stroma of the mucous membrane is infiltrated with young connective tissue and round cells, and the glands are enlarged and greatly convoluted. In the latter stages it is common to find an atrophy of the whole mucous membrane. The glands shrink and disappear; the vessels show a marked thickening of their walls with narrowing of the lumen, which may become wholly closed. The mucous membrane becomes dry, the epithelium falls off or is much atrophied, the cells in the stratum proprium and the submucosa disappear, and a thin layer of stiff connective tissue develops. Such atrophic changes are generally found in connection with processes that are designated as ozena; ulcers in the altered mucous membrane are also occasionally found.

Chronic catarrh of the nasal mucous membrane is not infrequently associated with the development of circumscribed and, later, pedunculated swellings or polypi, the structure of which resembles that of the mucosa; the stroma is fibrous connective tissue, which is more or less swollen by virtue of an accumulation of edematous fluid in its meshes; at times this may give it a typical myxomatous appearance, especially when the fluid contains mucinous substances; the nuclei become spindle-shaped, and when the cell-body can be demonstrated, it is found to present numerous radiating processes. In addition, the spaces of the tissue contain numerous round cells, of the type of lymphocytes, which are found especially numerous in the vicinity of the vessels, and also some polymorphonuclear leukocytes. The glands of the normal mucous membrane are found also in the polypoid outgrowth; not infrequently, the glands show an extraordinary development, and when their

ducts are closed or narrowed, cystic dilatations result, which may become so large and so numerous that they constitute the principal mass of the polyp (cystic polyp). The surface of these new formations are covered with cylindric epithelium-at least, in their earlier stages; later, the epithelium may become much reduced or even wholly destroyed. On the whole, these polyps are best regarded as fibromata, which, when edematous, approach the type of myxomata. The word polyp does not convey any idea of the histologic structure of the growth; it refers only to the gross form—i. e., a pedunculated growth, no matter whether it is a fibroma, sarcoma, or epithelioma.

Infectious processes, such as tuberculosis, syphilis, and glanders, are met with in the nasal mucous membrane. The tuberculous and syphilitic lesions differ in no way from the same processes as they occur in other mucous membranes; and the nodules of glanders, which may develop upon the nasal lining of man and animals, are also composed of epithelioid cells-derived from the fixed cells -and lymphocytes and leukocytes. Central necrosis occurs early, and may lead to perforation of the free surface and the formation of sinuous ulcers.

Diphtheria of the nose, which is not so infrequent, presents no histologic peculiarities, and further reference is made to what is said concerning diphtheria of the larynx, trachea, and the pharynx.

LARYNX, TRACHEA, AND BRONCHI.

The larynx, trachea, and bronchi are covered by a mucous membrane lined with ciliated cells. Each epithelial cell passes through the entire thickness of the epithelial covering, but on account of mutual pressure the form may be varying, such as conic and spindle-shaped. The nuclei are situated at the broadest part of the cell, and,

« PreviousContinue »