Lymphatic vessel

“ The vessels divide and anastomose very freely, and for this reason they do not, like the veins, increase in calibre as they approach their destination. It is usual to divide the lymphatic vessels into a superficial and a deep set; speaking generally, the superficial ones are found near the course of the superficial veins, while the deeper ones accompany the arteries. Probably any single drop of lymph passes sooner or later through one or more lymphatic glands, and so those vessels which are approaching a gland are called afferent, while those leaving are spoken of as efferent lymphatics. ”

“ The lymphatics far exceed the veins in number and perform a function similar to the veins, gathering waste material from the tissues, also the digested food called chyle, from the stomach and intestines. The lymphatic vessels, also the lacteals which absorb the chyle, all pass through glands, which are extremely numerous, where certain deleterious substances are extracted from the lymph before it is emptied into the blood stream. ”

“ The dilatation of a vessel may result from thinning or loss of contractility of its walls, caused by increased resistance to the onward movement of the fluid, and by the lesser extensibility of the intima than of the adventitia.
Lymphatic varices usually have their beginning in the vessels and extend to the plexuses, but the plexuses may be alone affected. Varicosities always extend backward from the point where the flow of the contained lymph is arrested, and may result from a repletion of each proximal intervalvular section with valvular incompetency. ”

“ If the blood vessels enlarge more than the lymphatic, haemolymph glands result, but if the lymphatic vessels become predominant ordinary lymphatic glands are formed. At an early stage in the embryo pig two thoracic ducts are formed, one on either side of the aorta, and the incomplete fusion of these may account for the division often found in man’s duct. ”

“ They are very pale in colour, often almost transparent and very thin-walled. Hence they are frequently difficult to find and dissect. These are the lymphatic vessels, and they are found to be returning a fluid from the tissues to the bloodstream. When traced back to the tissues they are seen to divide and ultimately to form minute anastomosing tubules, the lymph capillaries. The capillaries finally terminate in the spaces between the structures of the tissue, but whether their free ends are closed or are in open communication with the tissue spaces is still undecided. ”

“ These capillaries then unite to form the lymph vessels and these then convey the lymph to the subclavian veins. The lymph is a colorless fluid and contains numerous blood corpuscles known as lymphocytes. But in those lymphatic vessels, which have their origin in the walls of the small intestines, the lymph, especially during digestion, contains a great amount of fat, so that it has a milky appearance, and for this reason the lymphatics of this region, have been termed lacteals. There are two main lymphatic trunks, the one on the left side is called the thoracic duct. ”

“ In birds, however, some of the lymphatics open into the sacral veins, and it is doubtful whether true lymphatic glands ever occur. In birds and mammals lymphatic vessels become more definite and numerous and are provided with valves. ”

“ The lymphatics of the head may be injected in a similar manner, the canula being introduced into the upper and lower lip, or into the bare surface at the end of the nose.
The internal lymphatic vessels may be injected by injecting the lymphatic glands with which they are connected. ”

“ Notwithstanding I have supposed dropsies to be connected with a peculiar state of force in the blood-vessels, yet I have not ventured to assert, that dropsies may not exist from an exclusive affection of the exhaling and absorbing vessels. I conceive this to be as possible, as for a fever to [188] exist from an exclusive affection of the arteries, or a hysteria from an exclusive affection of the nervous system. Nothing, however, can be said upon this subject, until physiology and pathology have taught us more of the structure and diseases of the lymphatic vessels. ”

“ The action of the lymphatic vessels counterbalances those of nutrition, and thus the form and size of every part of the body is preserved. When their action exceeds that of the nutrient vessels, the body emaciates; when it is deficient, plethora is the result. In youth, they are less active than the nutrient vessels, and the limbs are plump ”

“ In nearly every tissue and organ of the body there is a marvelous network of vessels, called the lymphatics. These are busily at work taking up and making over waste fluids or surplus materials derived from the blood and tissues generally. The lymphatics seem to spring from the parts in which they are found, like the rootlets of a plant in the soil. They carry a turbid, slightly yellowish fluid, called lymph, very much like blood without the red corpuscles. The lymph is carried to the lymphatic glands where it undergoes certain changes to fit it for entering the blood. ”

“ In lymph vessels the cancer cells may merely accumulate so as to fill the lumen and form indurated cords, or they may proliferate and give rise to secondary nodules along the course of the vessels. When the lymphatic network in the skin is diffusely infected, the appearance is either that of a multitude of secondary nodules or of a diffuse thickening, so that the skin comes to resemble coarse leather. ”

“ If, moreover, as is probably the case, the lymphatics commence as closed capillaries, we have a further difficulty in explaining how the fluid is driven through the lymphatic wall. Either we must imagine the wall to be porous or there must be a greater pressure outside than inside, and it is very difficult to conceive how this is possible. As a general conclusion, then, it seems much more probable that we are here dealing with a secretory process, and that the active tissue produces some substance or substances—it may be carbonic acid—which throws the lymphatic capillary cells into activity. ”

“ The subjacent connective tissue is increased in bulk, having, especially in the case of the scrotum, a yellowish, blubbery appearance from lymphous infiltration. A large quantity of fluid wells out on division of such tissues. The muscles, nerves, and bones are not necessarily diseased, although in rare instances they may be degenerated and slightly or considerably atrophied from pressure. The blood-vessels are large; the lymphatics dilated; the associated lymphatic glands, both of the same side and, very often, of the opposite side, enlarged and dense. ”

“ Most people who are not critically ill need to walk at least 200 yards twice a day, with assistance if necessary, if only to move the lymph through the system. The lymphatic system is a network of ducts and nodes which are distributed throughout the body, with high concentrations of nodes in the neck, chest, arm pits, and groin. ”

“ In the milky fluid obtained by tapping such a hydrocele we may find filarial embryos.
Besides chylous hydrocele we may have a chylous ascites or a chylous diarrhoea. Where there is no obstruction to the thoracic duct there is less fat and the condition is more properly a lymphocele rather than a chylocele. The same distinction is applicable to the other conditions connected with lymphatic varices due to lymphatic obstructions other than that of the thoracic duct. ”

“ On investigating the conditions under which in healthy individuals an increased number of lymphocytes enter the blood-stream, we have in the first place to notice the digestive canal, whose wall contains a thick layer of lymphatic tissue. According to the results of Rieder the proportion of the lymphocytes to polynuclears is practically normal in the leucocytosis of digestion, indeed the lymphocytes are rather in excess. ”

“ In fishes, for instance, there is a large subvertebral lymph sinus surrounding the aorta and another within the spinal canal. In Amphibia the subvertebral sinus is also found, and in the Anura (frogs and toads) there is a great subcutaneous lymph sinus. Lymph hearts are muscular dilatations of vessels and are found in fishes, amphibians, reptiles and bird embryos, and drive the lymph into the veins; they are not known in adult mammals. ”

“ With great patience and moderate pressure one can succeed in artificially injecting the lymphatics without causing extravasation. It may even be the case that only one, or at most one or two ampullæ are affected. Microscopically the ampullæ and trabeculæ are found more or less filled with brown bodies or globi. These are evidently lymph cells which have become filled with bacilli and their degenerative products—granules.
One could hardly have a better demonstration of the functions of the lymphatic glands, as filters, than in these leprous glands. The circulation through them is not arrested ”

“ For my own part, I am of opinion that the small-pox is a disease of the lymphatic system only, and my opinion seems to be confirmed by the impossibility of communicating [Pg 76] the infection by inoculating with the blood. Be this as it may, it is indisputably true, that the crude lymph is sufficient to give the infection, and that there is no necessity to draw blood at the time of incision. Add to this, the frequent tumour of the lymphatic glands in the axilla soon after the operation. ”

“ The lymphatic engorgement either exists in the infant as in the adult or has its analogue in the enlargement of the spleen and liver—especially the former, which is almost as constant a phenomenon as is general glandular enlargement in acquired syphilis. The same pathological changes occur, the same infiltration of cells producing, according to their situation, papular, pustular, or mucous patches, or inflammation of such structures as the iris, choroid, or retina. ”

“ A great number of microbes enter our system through the mouth with the air and food, but happily they are antagonized by the saliva and the gastric juice, which are able to destroy a large number of these obnoxious invaders. Like the ductless glands, the lymphatic glands are closely connected with one another, and thus changes in one of these glands are apt to be followed by changes in the others. Hence we can see how a lymphatic structure contained in the intestine,—the appendix,—can often become inflamed after previous inflammation of the tonsils. ”

“ If it retains the capacity of growth or of stimulating a like growth, there results a more or less complete transformation of the gland into a morbid tissue like that from which the fragments came. Adjoining lymph-glands may become infected from the first, until eventually an entire series becomes more or less completely transformed into morbid growths. A like invasion of the lymphatic glands may take place through a continuous extension along the lymph-vessels ”

“ Like blood it clots, but clots badly, only forming a soft clot which quickly contracts. The lymph collected from a lymphatic before it has passed through a lymph gland contains a few leucocytes, and though the number of lymphocytes is greater in the lymph after it has flowed through a gland it is never very great. In normal states there are no red blood corpuscles.
The total solids amount to 3.6 to 5.7%, the variations depending upon the amount of protein present. The lymph during hunger contains only a minute quantity of fat. ”

“ The patient on whom this observation was made was the subject of lymph scrotum and varicose groin glands. His blood contained large numbers of embryo filariæ which exhibited the anatomical features and periodicity characteristic of microfilaria bancrofti. One morning he committed suicide by swallowing a large quantity of dilute hydrocyanic acid. Death was almost instantaneous. At the post-mortem examination, made six hours later, a huge lymphatic varix was found occupying the pelvis and back part of the abdominal cavity. ”

“ Not only is deglutition difficult, but it is difficult to open the mouth sufficiently to inspect the fauces, and attempts to do so cause much pain. The lymphatic glands, which lie in the inflamed area and participate in the inflammation, are greatly enlarged by hyperplasia, the round granular lymph-cells multiplying so abundantly that the glands increase to many times their normal size. Most of the tumefaction is, however, due to extension of the inflammation to the connective tissue of the neck. ”

“ An accessory cause can sometimes be observed where a local irritation gives rise to swelling of the adjacent lymphatic glands and this goes on to distinct lymphadenoma.
Lesions in the Lymph Glands. The hyperplasia may affect but a single group of glands, more commonly a number of groups, and often nearly all. In one case only of leukæmia in the lower animals, a dog, has Nocard failed to find the lymph glands affected. In the horse he has found the sublumbar glands alone weighing 14.5 kilogrammes, 11 k. and 8 k. They compressed the posterior aorta and vena cava and had caused extensive ascites. ”

“ Pathology of lymphatic varix.— In consequence of the rich anastomosis existing between the contiguous lymphatic areas, on filarial obstruction occurring in one of them a compensatory lymphatic circulation is sooner or later established. ”

“ Acute inflammation more commonly supervenes on inflammation in the area drawn upon by the afferent vessels of the gland. In inflammations generally the adjacent lymphatic glands become congested. In lymphangitis it is so in a marked degree. In external parts we can follow this by careful observations during life, in internal organs we often find the glandular enlargement after death. ”