RESUMO
The use of avian animal models has contributed to the understanding of many aspects of the ontogeny of the hematopoietic system in vertebrates. However, specific events that occur in the model itself are still unclear. There is a lack of consensus, among previous studies, about which is the intermediate site responsible for expansion and differentiation of hematopoietic cells, and the liver's contribution to the development of this system. Here we aimed to evaluate the presence of hematopoiesis in the yolk sac and liver in chickens, from the stages of intra-aortic clusters in the aorta-genital ridges-mesonephros (AGM) region until hatching, and how it relates to the establishment of the bone marrow. Gallus gallus domesticus L. embryos and their respective yolk sacs at embryonic day 3 (E3) and up to E21 were collected and processed according to standard histological techniques for paraffin embedding. The slides were stained with hematoxylin-eosin, Lennert's Giemsa, and Sirius Red at pH 10.2, and investigated by light microscopy. This study demonstrated that the yolk sac was a unique hematopoietic site between E4 and E12. Hematopoiesis occurred in the yolk sac and bone marrow between E13 and E20. The liver showed granulocytic differentiation in the connective tissue of portal spaces at E15 and onwards. The yolk sac showed expansion of erythrocytic and granulocytic lineages from E6 to E19, and E7 to E20, respectively. The results suggest that the yolk sac is the major intermediate erythropoietic and granulopoietic site where expansion and differentiation occur during chicken development. The hepatic hematopoiesis is restricted to the portal spaces and represented by the granulocytic lineage.
Assuntos
Células da Medula Óssea/citologia , Hematopoese , Fígado/citologia , Fígado/embriologia , Saco Vitelino/citologia , Saco Vitelino/embriologia , Animais , Embrião de Galinha , Eritropoese , Granulócitos/citologia , Fígado/irrigação sanguínea , Veia Porta/citologia , Veia Porta/embriologia , Fatores de TempoRESUMO
The left lateral division or left anatomical lobe of the liver is subdivided into posterior lateral or S2 and the anteriorlateral or S3 segments. Because this lobe is widely used in hepatic transplantation, the ramifications of the portal veinand of the hepatic veins have been extensively studied. The aim of this study was to investigate the frequency ofcases in which it is possible to delimit the S2 and S3 hepatic segments. Forty livers from Brazilian subjects ofEuropean and African descent were fixed in neutral formalin solution and dissected. In segment S2, there was alwaysa portal branch located dorsally to the left hepatic tributary. In segment S3, there were three types of interdigitationsdistributed among two portal branches and two hepatic tributaries. In type A (26/40 cases, 65%), the tributariescrossed the dorsal portal branch posteriorly. In subtype A1 (19/26 cases), the tributaries pinched the ventral branch,and in subtype A2 (7/26 cases), they crossed the ventral branch posteriorly. In type B (11/40 cases, 27.5%), the twotributaries pinched the dorsal portal branch, with both pinching the ventral portal branch in subtype B1 (7/11 cases)but only the ventral tributary crossing the latter branch in subtype B2 (4/11 cases). In type C (3/40 cases, 7.5%), theventral and dorsal tributaries crossed the dorsal portal branch anteriorly, with both vessels also crossing the ventralportal branch anteriorly in subtype C1 (2 cases) and only the ventral tributary crossing this branch in C2 (1 case). Inall cases, it was possible to differentiate S2 from S3, even when in type C cases there was no hepatic tributaryseparating them. Moreover, in 23/40 cases (57.5%) there was a fissural umbilical vein greater than 5 mm in diameterand, in 5/23 cases this vein superficially crossed the portal branch destined to segment S3.
Assuntos
Humanos , Masculino , Feminino , Veias Hepáticas , Veia Porta , Veia Porta/anatomia & histologia , Veia Porta/citologia , Veias Hepáticas/anatomia & histologia , Veias Hepáticas/ultraestrutura , Brasil , Cadáver , Fígado/irrigação sanguíneaRESUMO
We previously reported that portal veins from mice infected with male Schistosoma mansoni exhibited an increased reactivity to 5-hydroxytryptamine (5-HT). Here, we extended our observations to mice infected by both male and female worms and we further investigated another constrictor agent and the mechanism(s) responsible for the enhanced maximal contraction ( E(max)). Bisexual infection increased the E(max) of 5-HT (from 0.66+/-0.06 mN.s to 1.56+/-0.38 mN.s), in a similar way to the unisexual (male) infection. Infection with male worms increased portal vein reactivity to acetylcholine, as revealed by a higher E(max) (1.03+/-0.2 mN.s) in relation to non-infected control animals ( E(max)= 0.54+/-0.08 mN.s). Sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase (SERCA) inhibition with 100 nM thapsigargin reduced the E(max) of 5-HT by 35% in both tissues, discharging a deficiency of SERCA pump in infected animals. In contrast, the number of voltage-dependent Ca(2+) channels (L-type) was higher in portal veins from infected than non-infected control mice. Inhibition of Ca(2+)-activated chloride channels (Cl(Ca)) with 10 micro M niflumic acid reduced the E(max) of 5-HT in portal veins more from infected than non-infected animals (remaining tension = 60.9+/-2.2% and 70.4+/-2.3%, respectively). Histopathological analysis revealed an increased content of collagen and elastin in portal veins from male S. mansoni-infected mice, compatible with an increased intraluminal pressure. In conclusion, male S. mansoni altered portal vein physiology, increasing the E(max) of two vasoconstrictors, possibly by increasing membrane depolarisation through a more effective opening of Cl(Ca) channels, with calcium entering through L-type Ca(2+) channels.
Assuntos
Veia Porta/fisiopatologia , Schistosoma mansoni/patogenicidade , Esquistossomose mansoni/fisiopatologia , Vasoconstrição , Acetilcolina/farmacologia , Animais , Cálcio/metabolismo , Relação Dose-Resposta a Droga , Feminino , Histocitoquímica , Masculino , Camundongos , Veia Porta/citologia , Veia Porta/patologia , Retículo Sarcoplasmático/efeitos dos fármacos , Retículo Sarcoplasmático/metabolismo , Esquistossomose mansoni/metabolismo , Esquistossomose mansoni/parasitologia , Esquistossomose mansoni/patologia , Serotonina/farmacologia , Fatores Sexuais , CaramujosRESUMO
Portal vein perfusion of rat's liver was carried out with Ringer's solution followed by 2.5 per cent glutaraldehyde. Liver samples were postifixed in osmium tetroxide, washed in distilled water, snap-frozen in Freon-12, and fractured at -150§C. After freeze-drying at -80§C., a thin layer of carbon and gold was applied under vacuum. Under the scanning electron microscope, the sinusoidal fenestrations and the relationships of the endothelial cells to hepatocyte microvilli and reticulin fibres were delineated. Images of bile canaliculi and adjoining plasma membranes were obtained. These techniques have great potential for the study of a variety of liver diseases. (AU)