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Segmentary design as constitution of lymphatic system
Petrenko Valeriy Michaylovich, PhD, ScD, professor, OLME Centre for reabilitation of motionless patients, St.-Petersburg,
E-mail: [email protected]
Segmentary design as constitution of lymphatic system
Abstract: Lymphatic system has segmentary construction on two levels of individual organization. General or periarterial and special or intervalvar segments of lymphatic system organize all its reactions on influences of environment.
Keywords: lymphatic system, constitution, segment, valve, artery.
Introductuion.
It is known many facts about structure of lymphatic system (LSy) in man and animals [4, 7, 8]. It is proposed much models of function of LSy as part of cardiovascular system, but mainly of lymphatic vessels (LV) — lymphatic hearts by L. Ranvier or lymphangions as valvar segments, functional units of LV according E. Horstmann and H. Mislin [2,6,8]. But generally accepted conception about organization of LSy at whole is absent.
Original feature of LSy in topography.
Usually LV and lymph nodes (LN) lie about blood vessels. And this is not accidentally. Primary veins always accompany arteries of embryo, part of these veins are turned off blood flow with formation of primary LV. Blood vessels invaginate in lumen of these LV with anlage of LN in fetuses. Wall of maternal LV transformates into capsule of LN (wall of marginal sinus), its internal part is infiltrated by lymphocytes, which migrate from blood microvessels of stromal anlage of LN (invagination in lumen of maternal LV) [7]. Arteries with the most high blood pressure, the most thick and compact walls among all vessels: 1) dominate in interactions with veins and lymphatic bed (LB), contact (fragmentation of embryonic vessels and direct massage of definitive vessels) and distant (over capillaries and tissue channels, blood supplying of tissues and organs in environment of LB as its external cuff — lymphiza-tion and “undirect” massage of LB); 2) more stable to pressure of surrounding organs and as pivot preserve stability of vascular bundles.
Lymphatic valves as morfogenetic folding adaptation of LB:
periodic knocks against of lymph anti-flows cause repeated local lymphodinamic strokes and
overstreching ofwalls of LB, arising and increasing of their residual deformations with look as circular folds [8]. Valves limit lymph flow back and thus prevent destructive lymphodinamic strokes. Valves divide LB on intervalvar segments with different structure: lymphatic postcapillaries consist of unmuscular intervalvar segments, which organize passive lymph flow out lymphatic capillaries; LV consist of muscular intervalvar segments or lymphangions, which may be contract themselves by deficit of energy of extravasal factors and actively move lymph to veins; LN is nodal or lymphoid lymphangion, it regulates as volume speed of lymph flow so composition of lymph. All intervalvar segments of LB have common structure: between entrance and outlet valves there is unvalvar part, but with different construction. The wall of lymphatic postcapillary consists of endothelium and (often) connective tissue. The wall of LV includes yet smooth myocyties, the wall ofLN — lymphoid tissue. The border valve belongs to both neighbouring intervalvar segments (wall of LB is uninterrupted). The cusps of closed valve divide lumen of neighbouring intervalvar segments on the autonomic compartments. Their dilatation by filling of lymph induces passive contract of intervalvar segment (pressure of surrounding tissues — external cuff of LB), and stretching of its walls — active contract (muscular cuff of lymphangion). Segmentary principle of construction extends on network of lymphatic capillaries. Mobile intercellular contacts of endothelium are maken and function as minivalves [5] on entrance oflumen oflymphatic capillary: they level variable current of fluid between tissue channels and lymphatic capillary and thus regulate filtration of tissue fluid in lumen of lymphatic capillary (lymphization). Thus LSy may be present
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Section 2. Biomedical science
as chain of intervalvar segments. Their construction become complicated progressively in orthograd direction: the endothelium of lymphatic capillary are supplemented by its folds (valves) and adventitia in the walls of lymphatic postcapillary, smooth myocy-ties — in the walls of LV, lymphoid tissue — in the walls of LN. This hierarchy in structure of definitive LSy recapitulares the main stages of development of LSy with connection with organogenesis (growth of functional loading on LB) in evolution and ontogenesis of vertebrates [7].
LN is part of uninterrupted lymphatic tract: walls and lumen of afferent LV pass into capsule and sinuses of LN, which continue into walls and lumen of efferent LV Their muscular layers interconnected too. LN is one of lymphangions in network of extraorganic LB. On structure and function capsule of LN is muscular cuff of nodal lymphangion, in connective tissue of which lymphocyties instil [8]. As in evolution of vertebrates, so in ontogenesis of man and mammal animals LN form at last among all sections of LB, on the base ofLV, but with participation of arteries and veins, which invaginate in lumen of LV. Then it is originated lymphoid parenchyma of LN as local transformation of the wall of maternal LV: macropfages and lymphocytes pass from blood microvessels of the invagination (stromal anlage of LN) into its intervascular connective tissue which grow up as lymphoid tissue into lumen of the LV [7].
Segments of LSy, their types and place in human organism.
Segmentary organization of LB is defined as structure of its walls (valves), so its topography (branching artery). I divide segments of LSy on: 1) general (common for LB and blood bed) or systemic; 2) special, own or local. I discern two types of the general or periarterial segments: 1) central, paraaortic (lymphatic ducts and their roots); 2) peripheral, subaortic, 2 a) regional or topographo-anatom-ical (about primary branches of aorta), 2b) organic, anatomical or subnodal (near organ, in basin of its regional LN of I order); 2c) microorganic, microanatomical or paraarteriolar (LV I order and their roots in microdistricts of microcirculatory bed in organ); 2d) root, primary or subarteriolar — lymphatic postcapillaries and their roots in modules and microdistricts of microcirculatory bed. I divide spe-
cial segments of LSy on unmuscular and muscular, lymphangions — on vascular and nodal. Structure of own segments ofLSy becomes complicated in orthograd direction: 1) at level of tissues in organs (in the places of lymphization) there are root general segments, they consist of unmuscular intervalvar segments; 2) on exit of organs and their coats (on withdrawal from vis a tergo) lymphangions appear; 3) at level of regional general segments lymphoid or nodal lymphangions supplement vascular lymphangions by means of including lymphoid tissue in the intima.
Own segments of LSy unite with another components of general segments of LSy by means of loose connective tissue, which may be transformates into lymphoid tissue of LN. In the walls of LB it may be distinguish own or segmentary apparatus (intervalvar segments) and oversegmentary apparatus of bipartite connections with surrounding tissues. The own apparatus includes inner layers of LB wall: in lymphatic capillaries and postcapillaries — endothelium, in LV and LN — intima (including lymphoid tissue in LN) and media. The intervalvar segments of LV and LN are surrounded by common case of uninterrupted adventitia. Connective tissue fibers entwine in superficial layers of LB adventitia uniting wall of LB with surrounding tissues and organs — mechanic drives of external cuff of tissue (extralymphatic) pump. Thus general segments of LSy are into corporal segments (corresponding neuro-vascular segments of human body at whole) — the aggregates of organs, blood suppling by one of branches of aorta, such artery is accompanied by nerve (s), vein (s) and LV
Typical anatomy of LSy and its function.
Literature contains few informations about connection of structure of LSy or its part with human constitution and somatotype [1, 3, 7].
Astenics and hyperstenics succumb to infections. It is may be to connect with hypofunction of lymphoid system. Different types of human constitution are characterized by principal development of different connective tissues (CT) [1]: the astenic type — flabby reacting, thin, gentle СТ (the reticular about sinuses of LN?); the fibrous type (~ muscular) — dense СТ (tendon of muscle near chyle cistern?); the pastose, lypomatose (digestive) type — loose
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Segmentary design as constitution of lymphatic system
and adipose СТ, inclined to delay of fluid (lymphatic plexuses?). Hence tightening of surrounding СТ (conductor of extravasal factor of lymph flow) leads to increasing of transport means of LB, including LN — from compact (parenchyma), immune type to the fragmentary (wide sinuses), transport.
In all ages narrowing with lengthening and widening with shortening of human body accompany similar changes in thoracic duct, including its general length, width of initial cistern and plexus of lumbar trunks, lowering and flattening of arch in the cervical part to its complete reduction. Lengthening and narrowing of human body are accompanied by magistralization of LB with decrease of number of vessels, but shortening and widening of human body — widening of LB by means of increase of number, branching and local widening of vessels to form plexus and cistern. People with dolychomorphyc build must have LB of “narrow” type (magistral form — simple confluence of lumbar trunks), people with brachimorphyc build — LB of “wide” type (vast plexus of lumbar trunks with chyle cistern). Such changes of thoracic duct accompany with corresponding changes of number and distribution of its valves on extent of the duct, which consists of intervalvar segments with different sizes and construction that determine different lymph flow including different types of function of lymphangions.
Conclusion.
Constitution or general construction of LSy, which determines its reactions on all influences of surroundings including pushes of lymph flow, is in the segmentary construction of all parts and sections of LSy. Its organization includes folding structure of LB walls, causing by fluctuations of lymph flow [8], and quasi-segmentary connection of LB with arteries. Topographo-anatomical segmentation of LB arises in embryos [7] and reflects external connections LB with its surroundings — source of extravasal factors of lymph flow. Functional, intervalvar segmentation of LB arises in fetuses and corresponds to impulsed lymphization in organs and partial lymph flow out organs, that causing cyclic organization ofvital activity of cells and tissues. In condition of deficit of own lymph flow energy LB intervalvar segments organize passive and supplementary active moving of lymph from organs to veins. Structure and regimen of function of LB intervalvar segments are determined by their topography: at each level of general segmentation, branching of the main artery of systemic segment of LB is divided on intervalvar segments with different construction of their walls. It corresponds to fluctuations of functional activity of surroundings: the metabolic activity of draining organs (lymphization as piston of tissue pump) and mechanic pressure of adjacent organs (external cuff of tissue pump).
References:
1. Bogomoletz А. А. Konstitution und Mesenchym. (In Germen). In: Academic Proceedings of Saratov State University. - Saratov, 1924. - Vol. 2. - N 1. - P. 305-306.
2. Horstmann E. Über die funktionelle Struktur der mesenterialen Lymphgefasse//Morphol. Jarb. -1951. - Bd. 91. - № 4. - S. 483-510.
3. Jdanov D. A. Surgical anatomy of thoracic duct, main lymphatic collectors and lymph nodes of the trunk. (In Russian). - Gorkey: Gorkey med.inst.,1945. - 308 p.
4. Kampmeier O. F. Evolution and comparative morphology of lymphatic system. - Springfield: C. Thomas, 1969. - 620 p.
5. Leak L. V., Burke J. F. Electron microscopic study of lymphatic capillaries in the removal of connective tissue fluids and particulate substances//Lymphology - 1968. - Vol. 2. - P. 39-52.
6. Mislin H. The Lymphangion//Lymphangiology. - Stuttgart - New York: Schaffauerverlag, 1983. - P. 165-175.
7. Petrenko V. M. Evolution and ontogenesis of the lymphatic system. Second edition. (In Russian). - SPb: DEAN, 2003. - 336 p.
8. Petrenko V M. Functional morphology of lymphatic vessels. Second edition. (In Russian). - SPb: DEAN, 2008. - 400 p.
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