Evidence for eosinophil recruitment, leukotriene B4 production and mast cell hyperplasia following Toxocara canis infection in rats

It is well known that eosinophilia is a key pathogenetic component of toxocariasis. The objective of the present study was to determine if there is an association between peritoneal and blood eosinophil influx, mast cell hyperplasia and leukotriene B4 (LTB4) production after Toxocara canis infection. Oral inoculation of 56-day-old Wistar rats (N = 5-7 per group) with 1000 embryonated eggs containing third-stage (L3) T. canis larvae led to a robust accumulation of total leukocytes in blood beginning on day 3 and peaking on day 18, mainly characterized by eosinophils and accompanied by higher serum LTB4 levels. At that time, we also noted increased eosinophil numbers in the peritoneal cavity. In addition, we observed increased peritoneal mast cell number in the peritoneal cavity, which correlated with the time course of eosinophilia during toxocariasis. We also demonstrated that mast cell hyperplasia in the intestines and lungs began soon after the T. canis larvae migrated to these compartments, reaching maximal levels on day 24, which correlated with the complete elimination of the parasite. Therefore, mast cells appear to be involved in peritoneal and blood eosinophil infiltration through an LTB4-dependent mechanism following T. canis infection in rats. Our data also demonstrate a tight association between larval migratory stages and intestinal and pulmonary mast cell hyperplasia in the toxocariasis model.

Características histomorfométricas do placentomo de vacas Nelore nos terços inicial, médio e final de gestação / Histomorphometric characteristics of Nelore cows placentome in the initial, middle, and third terms of gestation

Avaliaram-se as características histomorfométricas do placentomo da vaca Nelore nos terços inicial, médio e final da gestação utilizando-se 52 úteros gestantes. Para a estimativa do estádio gestacional, foram utilizados aspectos do desenvolvimento fetal. Foram coletados fragmentos de um placentomo localizado no corno uterino ipsilateral ao corpo lúteo, os quais foram imersos em solução de formol e, posteriormente, processados histologicamente, incluídos em parafina e corados com hematoxilina-eosina. O estudo das proporções volumétricas foi feito utilizando-se microscópio de luz equipado com ocular integradora. Foi feita, também, a quantificação das células epiteliais nas criptas das carúnculas por meio de microscopia de luz e uma ocular micrométrica com 100 divisões. Foi verificado decréscimo no número das células maternas do epitélio das criptas no final da gestação. Os números médios das células binucleadas do trofoblasto, nos terços inicial, médio e final da gestação, mantiveram-se semelhantes, bem como a proporção volumétrica dos componentes dos tecidos conjuntivos materno e fetal e dos vasos no tecido materno. No tecido fetal, ocorreu aumento gradativo do tecido conjuntivo nos terços inicial, médio e final.

Histomorphometric characteristics of the placentome of the Nelore cow in the initial, medium, and final trimesters of pregnancy were evaluated using 52 pregnant uteri. For the estimation of the gestational age, aspects of fetal development were used. Fragments of a placentome of the uterine horn ipsilateral to the corpus luteum, which were immersed in formalin solution were collected, and processed for routine histological technique, included in paraffin, and stained with hematoxylin-eosin. The study of the volumetric proportion was done using a light microscope equipped with an integrated ocular. It was also made the quantification of the epithelial cells in the crypts of caruncles by light microscopy and with the help of a micrometric ocular with a grid of 100 divisions. It was found a decrease in the number of maternal cells of the epithelium in the crypts in advanced pregnancy. The average number of binucleate trophoblast cells remained similar throughout gestation, as well as the volumetric proportion of components of the maternal and fetal connective tissue and maternal blood vessels. For the fetal tissues, there was a progressive increase in the connective tissue in the three trimester of pregnancy.