Online Encyclopedia
Search over 40,000 articles from the original, classic Encyclopedia Britannica, 11th Edition.
MAMMARY GLAND (Lat. mamma)
Online EncyclopediaEncyclopedia Home :: MAL-MAR
del.icio.us it!
|
MAMMARY GLAND (See also:Lat. mamma) , or See also:female See also:breast, the See also:organ by means of which the See also:young are suckled, and the See also:possession of which, in some region of the See also:trunk, entitles the See also:animal bearing it to a See also:place in the See also:order of See also:Mammalia. See also:Anatomy.—In the human female the gland extends vertically from the second to the See also:sixth See also:rib, and transversely from the edge of the sternum to the See also:mid axillary See also:line; it is embedded in the See also:fat superficial to the See also:pectoralis See also:major muscle, and a See also:process which extends toward the armpit is sometimes called the axillary tail. A little below the centre of the glandular swelling is the nipple, surrounding which is a pigmented circular patch called the areola; this is studded with slight nodules, which are the openings of areolar glands secreting an oily fluid to protect the skin during suckling. During the second or third See also:month of pregnancy the areola becomes more or less deeply pigmented, but this to a large extent passes off after lactation ceases. In structure the gland consists of some fifteen to twenty lobules, each of which has a lactiferous duct opening at the See also:summit of the nipple, and branching in the substance of the gland to See also:form secondary lobules, the walls of which are lined by cubical epithelium in which the See also:milk is secreted. These secondary lobules project into the surrounding fat, so that it is difficult to dissect out the gland cleanly. Before opening at the nipple each lactiferous duct has a fusiform See also:dilatation called the See also:ampulla. After the See also:child-bearing See also:period of See also:life the breasts See also:atrophy and tend to become pendulous, while in some See also:African races they are pendulous throughout life. See also:Variations in the mammary glands are See also:common; often the See also:left breast is larger than the right, and in those rare cases in which one breast is suppressed it is usually the right, though suppression of the breast does not necessarily include See also:absence of the nipple. Supernumerary nipples and glands are not uncommon, and, when they occur, are usually situated in the mammary line which extends from the anterior axillary See also:fold to the spine of the pubis; hence, when an extra nipple appears above the normal one, it is See also:external to it, but, when below, it is nearer the See also:middle line. The See also:condition of extra breasts is known as polymasty, that of extra nipples as polythely, and it is interesting to See also:notice that the latter is commoner in See also:males than in See also:females. 0. See also:Ammon (quoted by Wiedersheim) (From A. F. See also:Dixon, See also:Cunningham's See also:Text See also:Book of Anatomy.) records the See also:case of a See also:German soldier who had four nipples on each See also:side. These nipples in the human subject are seldom found below the costal margin. In normal males the breast structure is See also:present, but rudimentary, though it is not very rare to find instances of boys about See also:puberty in whom a small amount of milk is secreted, and one case at least is recorded of a See also:man who suckled a child. A functional condition of the mammary glands in men is known as gynaekomasty. (For further details see The Structure of Man, by R. Wiedersheim, translated by H. and M. See also:Bernard, and edited by G. B. Howes, See also:London, 1895.) See also:Embryology.—There is every See also:probability that the mammary glands are modified and hypertrophied sebaceous glands, and transitional stages are seen in the areolar glands, which sometimes secrete milk. At an See also:early See also:stage of foetal life a raised patch of ectoderm is seen, which later on becomes a saucer-like depression; from the bottom of this fifteen or twenty solid processes of cells, each presumably representing a sebaceous gland, grow into the mesoderm which forms the connective-See also:tissue stroma of the mamma. Later on these processes See also:branch. The last stage is that the centre of the mammary See also:pit or saucer-like depression once more grows up to form the nipple, and at See also:birth the processes become tubular, thus forming lactiferous ducts. The glands grow little until the See also:age of puberty, but their full development is not reached until the birth of the first child. See also:Comparative Anatomy.—In the See also:lower Mammals the mammary line, already mentioned, appears in the embryo as a See also:ridge, and in those which have many young at a birth patches of this develop in the thoracic and abdominal regions to form the mammae, while the intervening parts of the ridge disappear. The number of mammae is not See also:constant to animals of the same See also:species; as an instance of this it will be found that in the See also:dog the number of nipples varies from seven to ten, though animals with many nipples are more liable to variation than those with few. When only a few young are produced at a See also:time the mammae are few, and it seems to depend on the convenience of suckling in which See also:part of the mammary line the glands are See also:developed. In the pouched Mammals (Monotremes and Marsupials) inguinal mammae are found, and so they are in most Ungulates as well as in the See also:Cetacea. In the elephants, Sirenia, See also:Chiroptera and most of the See also:Primates, on the other See also:hand, they are confined to the See also:pectoral region, and this is also the case in some Rodents, e.g. the See also:jumping See also:hare (Pedetes caffer). In the monotremes the mammary pit remains throughout life, and the milk is conducted along the hairs to the young, but in other Mammals nipples are formed in one of two ways. One is that already described in Man, which is common to the Marsupials and Primates, while in the other the margin or vallum of the mammary pit grows up, and so forms a nipple with a very deep pit, into the bottom of which the lactiferous ducts open. The latter is regarded as the See also:primary arrangement. In the monotremes the mammae are looked upon, not as modified sebaceous glands, as in other Mammals, but as altered sweat glands. It is further of See also:interest to notice that in these See also:primitive Mammals the glands are equally developed in both sexes, and it is thought that among the bats the male often assists in suckling the young (see G. See also:Dobson, Brit. Museum See also:Cat. of the Chiroptera, London, 1878). These facts, together with the occasional occurrence of gynaekomasty in man, make it probable that the ancestral Mammalwas an animal in which both sexes helped in the process of lactation. For further details and literature up to 1906 see Comparative Anatomy of Vertebrates, by R. Wiedersheim, adapted by W. N. See also:Parker (1907), and See also:Bronn's Classen and Ordnungen See also:des Thierreichs. (F. G. P.) Diseases of the Mammary Gland.—Inflammation of the breast (mastitis) is See also:apt to occur in a woman who is suckling, and is due to the presence of septic micro-organisms, which, as a See also:rule, have found their way into the milk-ducts, the lymphatics or the See also:veins, through a crack, or other See also:wound, in a nipple which has been made sore by the See also:infant's vigorous attempts to obtain See also:food. Especially is this septic inflammation apt to occur if the nipple is depressed, or so badly formed that the infant has difficulty in feeding from it. The inflamed breast is enlarged, See also:tender and painful, and the skiff over it is hot, and perhaps too reddened. The woman feels See also:ill and feverish, and she may shiver, or have a definite rigor—which suggests that the inflammation is See also:running on to the formation o an See also:abscess. The abscess may be suPerficial to, or beneath, the breast, but it is usually within the breast itself. The infant should at once be weaned, the milk-tension being relieved by the breast-See also:pump. Fomentations should be applied under waterproof jaconette, and the breast should be evenly supported by a bandage or by the corsets. See also:Belladonna and glycerine should be smeared over the breast, with the view of checking the secretion of milk, as well as of easing See also:pain. But before this is done six or eight leeches may be applied. On the first indication that See also:matter is See also:collecting, an incision should be made, for if the matter is allowed to remain locked up in the breast tissue the abscess will rapidly increase in See also:size, and the whole of the breast may become infected and destroyed. Supposing that, in making the incision, no pus is discovered, the See also:relief to the vascular tension thus afforded will be nevertheless highly beneficial. The operation had better be done under a See also:general anaesthetic, so that the surgeon can introduce a probe, or his See also:finger, into the wound, breaking down the partitions which are likely to exist between See also:separate abscesses, and thus enable them to be drained through the one opening. As the See also:discharge begins to cease, the tenderness subsides, and See also:gentle See also:massage, or See also:firm strapping of the breast, will prove useful. The general treatment will consist in the See also:administration of an aperient, and, the See also:tongue being clean, in prescribing such drugs as See also:quinine, strychnia and See also:iron. The See also:diet should be liberal, but not carried to such excess that the See also:power of digestion and absorption is overtaxed. During the early acute stage of the disease small doses of morphia may be necessary. When the tongue has cleaned, a little See also:wine may be given with See also:advantage. Chronic See also:Eczema around the nipple of a woman See also:late in life, with, perhaps, localized ulceration, is known as See also:Paget's Disease. The importance of it is that cancerous infiltration is apt to pass from it along the milk-ducts and to involve the breast in See also:malignant disease. Hence, when eczema about the nipple refuses to clear up under the See also:influence of soothing treatment, it is well to insist on the removal of the entire breast. Sometimes this eczema is malignant from the beginning, being associated with the active prolifization of the See also:epithelial cells of the milk-ducts, and with their See also:escape into the surrounding tissues. The nipple is retracted in most of these cases, which, however, are not often met with. Chronic Mastitis is of frequent occurrence in See also:women who are past middle age. The part of the breast involved is enlarged, hard, and more or less tender and painful. It is sometimes impossible clinically to distinguish this disease from See also:cancer. True, the See also:tumour is not so definite or so hard as a cancer, nor is it attached to the skin, nor to the muscles of the See also:chest See also:wall, and if there are any glands secondarily enlarged in the See also:arm-pit they are not so hard as they may be in cancer.. But all these are questions of degree. It is, of course, highly inadvisable to leave tt to time to clear up the diagnosis, for a chronic mastitis, See also:innocent at first, may eventually become cancerous. If in any case the difficulty of distinguishing a chronic mastitis from a malignant tumour of the breast is insuperable, the safest course is to remove the breast and have it examined by the See also:microscope. The See also:suggestion, sometimes made, as to the preliminary removal of a small piece of the tumour for examination is not to be recommended. A See also:simple glandular tumour, fibro-adenoma, is apt to be found in the breasts of youngish women, who may possibly give an See also:account of some See also:blow or other injury; there may, however, be no See also:history of injury. The tumour is smooth, rounded or See also:oval, and lies loose in the midst of the breast; as a rule it is not tender. It is not associated with enlarged glands in the arm-pit. The tumour had best be removed, though there is no urgency about the operation, as the growth is absolutely innocent. There is, however, no telling as to what course an innocent tumour of the breast may take as middle age comes on. Cysts of the Breast.—A galactocele is a tumour due to the locking up of milk in a greatly dilated duct. Other forms of cystic disease may be due to serous or hydatid fluid, or to thin pus, being surrounded by fibrous walls. Such cysts are best treated by See also:free incision, and by passing a See also:gauze dressing into their depths. If the tissue is occupied by many cysts, the whole breast had better be removed. Cancer of the Breast may be met with in men as well as in women; in men, however, it is very rare. It is commonest in women between Ampulla Ducts Lobule of gland the ages of See also:forty and fifty. It is sometimes met with in women of twenty; and the younger the individual the more malignant is the disease. Married life seems to have no effect as regards the incidence of the disease, but it often happens that a breast which gave trouble during the period of suckling becomes later the subject of cancer; in other cases there is a clear history of the attack having followed an injury. It is, thus, as if inflammatory changes in the breast were the See also:direct cause of a later cancerous invasion. Though it is impossible to affirm that See also:heredity has a See also:great influence in the incidence of cancer, it is, nevertheless, remarkable that the members of certain families are unusually prone to the disease. The See also:chief feature of a cancerous tumour of the breast is its great hardness. The technical name for the growth is scirrhus (Gr. astpos, owoulppos, any hard coat or covering, See also:stucco), from its stony hardness. The tumour consists of a dense framework of fibrous tissue, with See also:groups of cancer-cells in the spaces. The malignancy of the disease depends upon the cells, not upon the fibrous tissue. In young subjects the cells predominate, but in old ones the See also:con-See also:traction of the fibrous tissue throughout the breast compresses and destroys the cells, and this sometimes to such an extent that there is at last nothing left at the site but contracted fibrous tissue, all trace of malignancy having disappeared. This variety of the disease is found in old See also:people, and is called atrophic cancer. The cells of a cancerous breast are apt to be carried by the lymphatics to the lymphatic glands in the arm-pit, and by the See also:blood-stream to the See also:spinal See also:column and to other parts of the See also:skeleton, and sometimes to the See also:liver, which thus becomes large and hard, or to the other breast. As the fibrous tissue around the tumour becomes invaded by the new growth it undergoes contraction (much as a See also:string becomes shorter when it is Wetted), and as this shortening of the fibrous bands increases the nipple may be retracted, and the breast may be closely See also:bound down to the chest-wall; and, further, the skin over-lying the tumour may be See also:drawn in towards the tumour so as to form a conspicuous dimple. Later, the See also:nutrition of this patch of skin may be so interfered with that it mortifies or breaks down, and thus a cancerous See also:ulcer is produced. This ulcer slowly spreads, and its See also:floor is covered with a discharge in which septic micro-organisms undergo cultivation; in this way the ulcer becomes highly offensive. By the use of antiseptic lotions and a frequent See also:change of dressings, however, all unpleasant See also:smell can be checked or prevented. As the ulcer extends it is apt to implicate large blood-vessels, so that serious, and. sometimes alarming, haemorrhages take place. And if the breast had previously been in pain, the bleeding is likely to give great relief. But repeated haemorrhages bring on increasing exhaustion, and thus materially hasten the end. There is at present only one trustworthy treatment for cancer, and that is its free removal by operation. The entire breast and the nipple must be sacrificed. At the present See also:day the operation itself is not a " dreadful " one. To be successful it must be very thorough, and it must be done early. The patient, being under an anaesthetic, feels nothing, and the subsequent dressings of the wound are attended with scarcely any pain. There need be but a couple of days of confinement to See also:bed, and when the wound has soundly healed the patient may be encouraged to use her arm. Should there be recurrence of cancerous nodules in or about the wound, their removal should be promptly and widely effected. The writer has records of one case in which between the first operation and the last See also:report there was a space of over twenty-nine years, and another of, fifteen years. Each of these patients had one extensive operation, and four or five smaller operations for dealing with recurrences. Each of them, how-ever, might be considered unlikely subjects for further return. For a superficial cancer the X-rays may be of service, but many applications of the rays are likely to be needed, and the case may possibly refuse to yield to their influence, and, after loss of valuable time, the disease may have eventually to be removed by the See also:knife. The great advantage which the treatment by the knife offers over every other method is that the growth can be cleanly, efficiently and promptly removed, and, with it, all the affected See also:lymph-spaces, and the lymphatic glands which are secondarily implicated. As regards the value of See also:radium in the treatment of cancer of the breast, the high expectations which were somewhat widely associated with this newly-found See also:element early in 1909 must be said to have been unjustified by any precise results. Injections of radium salts have been made into the substance of a cancer, and tubes of See also:aluminium containing the See also:salt have been introduced into the growth, but no deep cancer has thereby been cured. Radium has also been exposed again and again on the See also:surface of the affected breast, but similarly with no great result. Unfortunately, whilst one is experimenting in the treatment of an operable cancer, the epithelial cells of the growth may be making their way towards distant parts, where no rays or emanations could possibly reach them. Whatever may be the future of radium as a therapeutic See also:agent in the treatment of cancer of the breast, it is certain that, on the facts as known at the beginning of 191o, the only safe course is to remove the breast by direct operation, together with the associated lymph-spaces and lymphatic glands. And if this is done promptly and thoroughly cancer of the breast will come more and more into the class of curable diseases. (E. O. Additional information and CommentsThere are no comments yet for this article.
» Add information or comments to this article.
Please link directly to this article:
Highlight the code below, right click, and select "copy." Then paste it into your website, email, or other HTML. Site content, images, and layout Copyright © 2006 - Net Industries, worldwide. |
|
|
[back] MAMMALIA (from Lat. mamma, a teat or breast) |
[next] MAMMEE APPLE, SOUTH AMERICAN |