RESUMO
BACKGROUND: Miguel Fernández was an Argentinian zoologist who published the first account of obligate polyembryony in armadillos. His contribution is here discussed in relation to his contemporaries, Newman and Patterson, and more recent work. FINDINGS: Fernandez worked on the mulita (Dasypus hybridus). He was able to get early stages before twinning occurred and show it was preceded by inversion of the germ layers. By the primitive streak stage there were separate embryonic shields and partition of the amnion. There was, however, a single exocoelom and all embryos were enclosed in a common set of membranes comprising chorion towards the attachment site in the uterine fundus and inverted yolk sac on the opposite face. He showed that monozygotic twinning did not occur in another armadillo, the peludo (Chaetophractus villosus). CONCLUSIONS: Fernández's work represented a major breakthrough in understanding how twinning occurred in armadillos. His work and that of others is of intrinsic interest to zoologists and has a direct bearing on the origin of monozygotic twins and birth defects in humans.
Assuntos
Anatomia Comparada/história , Tatus/embriologia , Embriologia/história , Desenvolvimento Embrionário , Camadas Germinativas/embriologia , Gemelaridade Monozigótica , Zoologia/história , Animais , Argentina , Tatus/crescimento & desenvolvimento , Tatus/fisiologia , Membranas Extraembrionárias/citologia , Membranas Extraembrionárias/embriologia , Membranas Extraembrionárias/fisiologia , Feminino , Pesquisa em Genética/história , Camadas Germinativas/citologia , Camadas Germinativas/fisiologia , História do Século XX , Masculino , Placentação , Gravidez , Especificidade da Espécie , Saco Vitelino/citologia , Saco Vitelino/embriologia , Saco Vitelino/fisiologiaRESUMO
Myometrial quiescence is a physiological stage of the myometrium during pregnancy. It is a period of active relaxation of the myometrial smooth muscle cells; myometrial quiescence is responsible for maintaining pregnancy. The precise mechanisms underlying myometrial quiescence have not been completely elucidated, although many mediators and cellular pathways have been described as playing a role. Fetal membranes (chorion and amnion) produce and release one or more substances that inhibit myometrial contractions, playing a central role in the maintenance of myometrial quiescence. Brain natriuretic peptide (BNP) is more potent than any other natriuretic peptide in inhibiting myometrial contractions in vitro. Brain natriuretic peptide is produced by the chorion and amnion, mainly during myometrial quiescence, and decreasing towards the end of pregnancy. Production of BNP is reduced in fetal membranes obtained from women in preterm labour. It is postulated that BNP, acting in a paracrine fashion, plays a key role in the maintaining myometrial quiescence and, therefore, controlling the duration of pregnancy. Furthermore, it is postulated that a premature decrease of BNP production by the fetal membranes may cause preterm labour and preterm birth.
Assuntos
Miométrio/fisiologia , Peptídeo Natriurético Encefálico/fisiologia , Contração Uterina/fisiologia , Adulto , Animais , Membranas Extraembrionárias/fisiologia , Feminino , Humanos , Peptídeo Natriurético Encefálico/uso terapêutico , Trabalho de Parto Prematuro/prevenção & controle , Comunicação Parácrina/fisiologia , GravidezRESUMO
The placenta of mammals is a structure formed by the juxtaposition of the fetal membranes and the maternal tissues. The main function of the placenta is to regulate the physiological interchange between the fetus and the mother as well as to operate as an important endocrine organ during the gestation. The placentomal fusions were characterized throughout gestation of cattle using macroscopic, histological and flow cytometry analyses. Analyzing the cell cycle phases with a flow cytometry, a balance between the G2M phase and apoptosis was observed, suggesting that the placentomal fusions do not interfere in the placentary maturation process, which is a pre-requirement for the fetal-maternal disconnection and the release of fetal membrane.
Assuntos
Bovinos/fisiologia , Placenta/fisiologia , Prenhez/fisiologia , Animais , Ciclo Celular/fisiologia , Proliferação de Células , Membranas Extraembrionárias/citologia , Membranas Extraembrionárias/fisiologia , Feminino , Citometria de Fluxo , Placenta/anatomia & histologia , Placenta/citologia , Gravidez , Útero/fisiologiaRESUMO
BACKGROUND: The prevalence of idiopathic spontaneous premature labor or without an evident clinical cause, has not been reduced with tocolytic treatments, suggesting that premature labor has multiple causes and infections play a not well-defined role. AIM: To perform microbiological studies of the amniotic fluid and of the lower genital tract in women with idiopathic premature labor and intact membranes, relating these findings with maternal and neonatal outcomes. PATIENTS AND METHODS: Women with pregnancies between 24 and 34 weeks, with premature labor and without an evident clinical cause were enrolled. Amniotic fluid and genital tract samples were obtained for traditional microbiological cultures. This information was related with delivery events and neonatal outcome. RESULTS: Sixty-three patients were included. The overall frequency of microbial invasion of amniotic cavity was 23.8% and of cervical or vaginal infection was 63.5% (in 39.7% there was only cervical or vaginal infection without involvement of the amniotic sac). Absence of infection was documented in 36.5% of women. Compared to patients without infection, women with microbial invasion of amniotic cavity had a higher rate of prematurity (73.3% p < 0.05), a higher rate of prematurity of less than 34 weeks (60% p < 0.01), a higher frequency of preterm rupture of membranes (40% p < 0.001), a shorter admission-to-delivery interval (median 3.0 days p < 0.01) and lower gestational age at delivery (median 33 weeks p < 0.01). Clinical chorioamnionitis and endometritis (20% p < 0.01) was observed only in patients with amniotic cavity infections. Severe asphyxia (26.7% p < 0.05) and neonatal admission to Intensive Care Units (46.7% p < 0.05) were more frequent and neonatal weight was less in the offspring of women with microbial invasion of amniotic cavity (2020 g median p < 0.01). CONCLUSIONS: In preterm labor with intact membranes, intraamniotic infection is the most frequent cause of prematurity and is associated with a higher prevalence of maternal and neonatal problems.
Assuntos
Líquido Amniótico/microbiologia , Infecções Bacterianas/complicações , Colo do Útero/microbiologia , Trabalho de Parto Prematuro/microbiologia , Vagina/microbiologia , Adolescente , Adulto , Membranas Extraembrionárias/fisiologia , Feminino , Humanos , Recém-Nascido , Trabalho de Parto Prematuro/epidemiologia , Gravidez , Prevalência , Doenças do Colo do Útero/complicações , Vaginose Bacteriana/complicaçõesRESUMO
El presente trabajo consiste en el estudio de 123 fichas clínicas y partogramas de mujeres hospitalizadas en el Servicio de Ginecología, Obstetricia y Neonatología del Hospital Gustavo Fricke de Viña del Mar (Chile), a las cuales se les aplicó el método inductor del trabajo de parto frecuentemente utilizado en dicho Servicio, conocido como RAM inductor. Se estudiaron las condiciones cervicales con las que se aplica, su evolución y complicaciones, de lo cual se desprendió que el RAM inductor es un método eficaz en la mayor parte de los casos, siempre y cuando se reúnan condiciones cervicales favorables