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PubMed1978

[Cutaneous metastases in digestive cancers (author's transl)].

Cutaneous metastases are seldom encountered in digestive cancers. The mechanism of their formation explains their low rate. The metastases spread mainly by the lymphatic system (especially in diffuse, spotty or pseudo-elephantiasic forms and in regional forms), however numerous lymph node filters found through out the lymphatic system limit the progression of neoplasic cells. On the contrary, metastases most often spread by retrograde involvement due to blocking of the lymphatic system. As for hematogenous metastases (generalized nodular forms or aberrant localizations), they are observed even less frequently than lymphatic ones; metastatic embolisms may effectively become blocked in capillaries, especially in the lungs and the liver, which constitutes a double barrier before the skin may be involved.

Adolescent↗
PubMedDate not supplied

Dendritic type, accessory cells within the mammalian thymic microenvironment. Antigen presentation in the dendritic neuro-endocrine-immune cellular network.

During mammalian ontogenesis, the thymic "pure" endodermal epithelial anlage develops and differentiates into a complex cellular microenvironment. Beginning the 7-8th week of intrauterine development, thymic epithelial cells chemotactically regulate (induce) numerous waves of migration of stem cells into the thymus, including the CD34+, yolk sac-derived, committed hematopoietic stem cells. In vitro experiments have established that CD34+ CD38dim human thymocytes differentiate into T lymphocytes when co-cultured with mouse fetal thymic organs. Hematopoietic stem cells for myeloid and thymic stromal dendritic cells (DCs) are present within the minute population of CD34+ progenitors within the mammalian thymus. The common myeloid, DC, natural killer (NK) and T lymphocyte progenitors have also been identified within the CD34+ stem cell population in the human thymus. Interactions between the endocrine and immune systems have been reported in various regions of the mammalian body including the anterior pituitary (AP), the skin, and the central (thymus) and peripheral lymphatic system. The network of bone marrow derived DCs is a part of the reticuloendothelial system (RES) and DCs represent the cellular mediators of these regulatory endocrine-immune interactions. Folliculo-stellate cells (FSC) in the AP, Langerhans cells (LCs) in the skin and lymphatic system, "veiled" cells, lympho-dendritic and interdigitating cells (IDCs) in a number of tissues comprising the lymphatic system are the cell types of the DC meshwork of "professional" antigen presenting cells (APCs). Most of these cells express the immunocytochemical markers S-100, CD1. CD45, CD54, F418, MHC class I and II antigens, Fc and complement receptors. FSCs are non-hormone secreting cells which communicate directly with hormone producing cells, a form of neuro-endocrine-immune regulation. As a result, an attenuation of secretory responses follows stimulation of these cells. FSCs are also the cells in the AP producing interleukin-6 (IL-6), and they have also been identified as the interferon-gamma responsive elements. FSCs also express lymphatic DC markers, such as DC specific aminopeptidase, leucyl-beta-naphthylaminidase, non-specific esterase, MHC class I and II molecules and various other lymphatic immunological determinants [platelet derived growth factor-alpha chain (PDGF-alpha chain), CD13, CD14 and L25 antigen]. There is strong evidence that such DCs in the AP, and similar ones in the developing thymus and peripheral lymphatic tissue are the components of a powerful "professional" antigen presenting DC network. These APCs contain a specialized late endocytic compartment, MIIC (MHC class II-enriched compartment), that harbors newly synthesized MHC class II antigens en route to the cell membrane. The limiting membrane of MIIC can fuse directly with the cell membrane, resulting in release of newly secreted intracellular MHC class II antigen containing vesicles (exosomes). DCs possess the ability to present foreign peptides complexed with the MHC molecules expressed on their surfaces to naive and resting T cells. There are a number of "molecular couples" that influence DC and T lymphocyte interaction during antigen presentation: CD/1/CD18 integrins, intercellular adhesion molecules (ICAMs), lymphocyte function associated antigen 3 (LFA-3). CD40, CD80/B7-1, CD86/B7-2, and heat-stable antigen. The "molecular couples" are involved in adhesive or co-stimulatory regulations, mediating an effective binding of DCs to T lymphocytes and the stimulation of specific intercellular communications. DCs also provide all of the known co-stimulatory signals required for activation of unprimed T lymphocytes. It has been shown that DCs initiate several immune responses, such as the sensitization of MHC-restricted T lymphocytes, resistance to infections and neoplasms, rejection of organ transplants, and the formation of T-dependent antibodies. (ABSTRACT TRUNCATED)

Animals↗
PubMed1995

[The lymph vessel system of the mouth cavity and pharynx].

BACKGROUND: The understanding of pathological processes involving the lymphatic system of the upper digestive tract requires a detailed knowledge of the lymphovascular architecture of this region. METHODS: The lymphatic system of the upper digestive tract was examined in 390 patients by different methods such as light microscopy, electron microscopy, histochemistry, and indirect lymphography. RESULTS: The mucous membrane of the upper digestive tract is permeated by two communicating lymphatic networks with regionally varying density. There are no areas without lymphatics. The lymphatic fluid of the nasopharynx flows from the posterior wall mainly towards the retropharyngeal and accessory lymph nodes (level II). The lymphatic flow from the buccal mucous membrane, the anterior floor of the mouth, the oral tongue, and the hard palate mostly drains toward the submandibular and craniojugular areas. Lymphatic fluid from the tonsils, the soft palate, and the hypopharynx flows primarily to the deep cervical lymph nodes (level II and III). CONCLUSION: These results are a basis for the understanding of a) secondary lymphatic edemas and b) frequency and direction of lymphogenous metastasis of carcinomas in this region. The direction of metastasis usually follows the physiologic lymphatic drainage. Metastasis towards untypical areas can in most cases be explained by an alteration of the lymphatic flow secondary to inflammation, radiotherapy, previous surgery, and subsequent scar formation or tumor growth.

Humans↗
PubMed2002

A stepwise model of the development of lymphatic vasculature.

Although lymphedema was first described more than a century ago, little progress has been made in understanding the mechanisms that cause it. Investigation of the normal development of the lymphatic system has been hindered by the lack of known lymphatic-specific markers. In 1902, F. Sabin proposed the most widely accepted theory about the origin of the lymphatic vasculature. This model proposed that isolated primitive lymph sacs bud from the endothelium of veins during early development; from these primary lymph sacs, the peripheral lymphatic system spreads by endothelial sprouting into tissues where local capillaries form. In 1999, we identified the homeobox gene Prox1 as the first specific marker of lymphatic endothelial cells. Functional inactivation of Prox1 in mice demonstrated that lymphangiogenesis requires the activity of this gene in a subpopulation of endothelial cells in embryonic veins. Prox1 promotes the development of the lymphatic vasculature by determining the final lymphatic fate of budding venous endothelial cells. On the basis of our findings, we propose a stepwise model of lymphangiogenesis in which lymphatic vasculature development is initiated by the specific expression of Prox1 in a subpopulation of vascular endothelial cells that subsequently adopt a lymphatic vasculature phenotype.

Animals↗
PubMed1986

Emulsion and activated carbon in cancer chemotherapy.

Based on a lipid-absorbing ability of lymphatic capillaries, a fat emulsion containing anticancer agents was applied to selectively deliver more increasing amounts of anticancer agents into regional lymph nodes. The emulsions, in which the drug solution is contained as the innermost phase or as oily soluble drug, yield high drug concentrations in the lymphatic system. Clinical trial of the emulsion method was carried out preoperatively for 180 patients with stomach cancer. As a result, the emulsion enhanced the chemotherapeutic effect of the anticancer agent on lymph node metastasis. About a 20 m mu-sized activated charcoal, in which anticancer agents were absorbed, selectively delivered the anticancer agents to the lymphatic system. The activated charcoal was also excellent carrier material for the lymphatic system, and we have applied it to patients with lymphatic metastasis.

Administration, Oral↗
PubMed1996

Lymph pathways associated with three types of follicle structure found in gut-associated lymphoid tissue of horse ileum.

In the horse ileum, lacteals in the villi are continuous with prelymphatic intercellular channels and a plexus of lymphatic sinuses in the lamina propria that encircle the domes of the follicle/dome structures and proprial follicles. These sinuses may act as the major entry site for many of the lymphocytes migrating from gut-associated lymphoid tissue via the lymphatic system. Vessels from this plexus penetrate the muscularis mucosae and lymph flows into lymphatic vessels within the interfollicular tissue between the follicles of both follicle/dome structures and lymphoglandular complexes (LGCs). No lymphatic vessels leave the follicles, but intercellular pathways of the follicles are continuous with those in the surrounding interfollicular tissue and follicular sinuses around the base of the follicles. These pathways appear to provide the only available lymphatic route for lymphocytes leaving LGCs to enter the lymphatic system. Lymph from the interfollicular tissue enters deep submucosal lymphatic vessels, containing prominent valves, which drain into other vessels transporting lymph from the surface of the ileum.

Animals↗
PubMed1981

Lymphatic abnormalities in protein-losing gastropathy, especially in Ménétrier's disease.

Histopathologic and lymphographic studies were performed in 4 patients with protein-losing gastropathy to elucidate the degree of lymphatic disorders and their contribution to clinical features. Histologic examination of gastric mucosa showed various degrees of hyperplasia of the surface epithelium and cystic dilatation of glands, which were considered to be characteristic findings of protein losing gastropathy. Moreover, in 3 of 4 patients there were edematous change of the lamina propria or the submucosa, and marked lymphangiectasia was seen in the submucosa of 3 patients and in the lamina propria of the other. Performed lymphograms showed an increase in the number of lymphatic vessels and lymph nodes in the iliopelvic and lumbar regions of 2 of the patients. This high incidence of lymphatic abnormalities in patients with protein-losing gastropathy suggested that such systemic lymphatic disorders were an important etiologic factor. However, such abnormalities in lymphatic system were not demonstrated in all cases of protein-losing gastropathy. Therefore, lymphatic disorders were not considered to be the primary cause of gastric protein loss, but the important factor that modifies the variety of lost protein and its clinical features.

Adult↗
PubMed1987

Lymphographic changes in young dogs after transplantation with adult worms of Dirofilaria immitis into the abdominal cavity.

Serial lymphographic studies were made in 4 dogs transplanted with adult worms of Dirofilaria immitis. Several changes of the lymphatic systems of the treated dogs such as dilatation, narrowing, tortuosity, backflow, collateral flow, leakage and lymphorrhea of lymphatics, as well as enlargement and filling defect of lymphnodes were observed at first 2 months after transplantation, comparing with the lymphograms before transplantation. Lymphographies were repeated further 4 and 7 months after transplantation. In our previous studies, the mechanism of chyluria due to human filariasis was not sufficiently explained beyond the speculation of the mechanical obstruction of lymphatic vessels by worm bodies. In the present studies, varied abnormal changes, especially back and collateral flow of the lymph vessels of popliteal and inguinal regions, could be produced in lymphatic systems in dogs by transplantation with adult worms of Dirofilaria immitis into peritoneal cavity. This fact suggests that a mechanism of filarial chyluria is due to systemic responses and changes of the lymphatics by substance of the body of filarial worms.

Animals↗
PubMed2005

The lymphatic vasculature: recent progress and paradigms.

The field of lymphatic research has been recently invigorated by the identification of genes and mechanisms that control various aspects of lymphatic development. We are beginning to understand how, starting from a subgroup of embryonic venous endothelial cells, the whole lymphatic system forms in a stepwise manner. The generation of genetically engineered mice with defects in different steps of the lymphangiogenic program has provided models that are increasing our understanding of the lymphatic system in health and disease. This knowledge, in turn, should lead to the development of better diagnostic methods and treatments of lymphatic disorders and tumor metastasis.

Animals↗