RESUMEN
OBJECTIVE: The objective of this article is to determine reference values for fetal biometric parameters in twin pregnancies and to compare these values between monochorionic and dichorionic pregnancies. METHODS: A retrospective cross-sectional study was conducted among 157 monochorionic and 176 dichorionic twin pregnancies between 14 and 38 weeks of gestation. Biometric measurements included the biparietal diameter (BPD), abdominal circumference (AC), femurs length (FL) and estimated fetal weight (EFW). To evaluate the correlation between biometric parameters and gestational age, polynomial regression models were created, with adjustments using the coefficient of determination (R(2) ). Comparison between monochorionic and dichorionic pregnancies was performed using analysis of covariance. RESULTS: The mean BPD, AC, FL and EFW for the dichorionic pregnancies were 56.16 mm, 191.1 mm, 41.08 mm and 816.1 g, respectively. The mean BPD, AC, FL and EFW for the monochorionic pregnancies were 57.14 mm, 184.2 mm, 39.29 mm and 723.4 g, respectively. There was a statistical difference between mono and dichorionic pregnancies for all the biometric parameters (BPD p = 0.012; AC p = 0.047; FL p = 0.007; EFW p = 0.011). CONCLUSION: Reference curves of biometric parameters in twin pregnancies were determined. Biometric parameters were statistically different between monochorionic and dichorionic pregnancies.
Asunto(s)
Corion/anatomía & histología , Desarrollo Fetal , Peso Fetal , Feto/anatomía & histología , Edad Gestacional , Embarazo Gemelar , Gemelos , Adulto , Estudios Transversales , Femenino , Humanos , Tamaño de los Órganos , Embarazo , Valores de Referencia , Estudios Retrospectivos , Ultrasonografía Prenatal , Adulto JovenRESUMEN
The type IV allantoplacenta has been described for the New World tropical scincids lizards of the genus Mabuya; it possesses the greatest morphological complexity known among viviparous squamates. Although a common morphological pattern has been observed in the few species of this lineage in which the allantoplacental morphology has been studied, some morphological variations may be present among species and populations. Here, we report morphological variation of the allantoplacenta of twelve populations of the genus Mabuya distributed in different geographical areas in northern South America using light microscopy. It is found that all the populations/species conserve a general arrangement of the placental structures. In the embryonic hemisphere there are a placentome, paraplacentome, and chorionic areolas; these structures are related to histotrophic nutrition. At the abembryonic hemisphere, there are absorptive plaques for histotrophic transfer and respiratory segments for gas exchange. However, in some populations some distinctive features in the placentome were found. The presence in the uterine syncytium of non syncytialized columnar cell groups, and invasive cells and apical projections of the chorionic cells directed toward the uterine syncytium, constitute a localized endotheliochorial placenta. Likewise, variations found in the abembryonic region include a greater morphological complexity, such as the folded and delimited absorptive plaques, and highly folded regions at the abembryonic pole (folded respiratory segments integrated with folded absorptive plaques). These specializations allow a larger surface for the passage of nutrients and respiratory exchange. Replication and the regionalized differentiation of the absorptive plaques were probably instrumental in the emergence of specialized structures for nutrient transport such as the placentome and the different types of absorptive plaques. These developmental processes appear to underlie the evolution of the placental complexity within thegenus Mabuya by the morphological variation of serial homologous structures.
Asunto(s)
Alantoides/anatomía & histología , Corion/anatomía & histología , Lagartos/anatomía & histología , Alantoides/citología , Animales , Corion/citología , Embrión no Mamífero/anatomía & histología , Embrión no Mamífero/citología , Desarrollo Embrionario/fisiología , Femenino , ReproducciónRESUMEN
A 40-year-old patient underwent intracytoplasmic sperm injection and assisted hatching, and a single embryo was transferred. Ultrasonography demonstrated a single gestational sac containing monochorionic tri-amniotic pregnancy. Several factors that have been implicated in the aetiology of monozygotic triple pregnancies after IVF appear to be present in this case. To avoid multiple pregnancies after IVF, it is time to have definite predictive factors for the occurrence of monozygotic multiple pregnancies as well as transferring only a single embryo.
Asunto(s)
Transferencia de Embrión , Embarazo Múltiple , Trillizos , Adulto , Corion/anatomía & histología , Transferencia de Embrión/efectos adversos , Femenino , Humanos , Masculino , Embarazo , Técnicas Reproductivas Asistidas/efectos adversos , Inyecciones de Esperma IntracitoplasmáticasRESUMEN
Se revisa la información de la literatura respecto de la estructura de las membranas ovulares, describiendo la zona de morfología alterada extrema, los mecanismos fisiopatológicos involucrados en la rotura prematura de membranas (destacando el proceso de apoptosis), relacionados a infección, isquemia placentaria, distensión de membranas, hemorragia coriodecidual, tabaquismo, relaxina, prolactina, hormona paratiroídea.
Asunto(s)
Humanos , Femenino , Embarazo , Recién Nacido , Complicaciones del Embarazo , Rotura Prematura de Membranas Fetales/fisiopatología , Trabajo de Parto Prematuro/complicaciones , Trabajo de Parto Prematuro/etiología , Amnios/anatomía & histología , Amnios/fisiopatología , Corion/anatomía & histología , Corion/fisiopatología , Recien Nacido Prematuro , Líquido Amniótico/microbiologíaRESUMEN
Loxosceles intermedia is a poisonous spider that has a wide distribution in southern Brazil, and constitutes a public health problem. In this study, the ovaries of mature females were examined by light and electron microscopy, and by histochemistry. Oocytes at all stages of development were observed in the same area of the mature ovarian wall, surrounded by a basement membrane and a proteic band. They were supported by a group of pedicular cells, which may function as follicular cells. No follicular cell was seen around the oocyte. Mature oocytes pass through the ovarian epithelial wall and are released into the ovarian lumen, covered by a vitelline membrane. The basement membrane and proteic band remain in the ovarian wall. On its way out, the oocyte is coated by proteins that will form the chorion. The presence of different coats throughout oogenesis, and at the time of egg release, is correlated with conditions that indicate fertilization occurs in the uterus lumen during oviposition.
Asunto(s)
Oocitos/crecimiento & desarrollo , Oogénesis/fisiología , Oviposición , Ovulación , Arañas/anatomía & histología , Arañas/fisiología , Animales , Membrana Basal/anatomía & histología , Corion/anatomía & histología , Corion/metabolismo , Proteínas del Huevo/metabolismo , Femenino , Fertilización , Oocitos/citología , Ovario/citología , Ovario/crecimiento & desarrollo , Ovario/metabolismo , Ovulación/fisiología , Arañas/ultraestructura , Vitelogénesis/fisiologíaRESUMEN
The egg chorion ultrastructures of the Hermanella-Traverella (Insecta: Ephemeroptera) species complex were studied from a comparative point of view and used for the first time in a cladistic analysis. Egg characters, along with other nymphal and adult morphological characters, were used to assess the phylogenetic relationships of the species complex. In order to test the value of egg characters, analyses were performed on three matrices: 1) egg characters alone, 2) adult and nymphal characters, and 3) adult, nymphal, and egg characters. The computer program Pee-Wee was used to carry out the analysis. The cladistic analysis confirmed the value and potential of egg chorionic characters in assessing the phylogenetic relationships among ephemeropteran species. Egg characters, when added to the nymphal and adult character matrix, provided extra support to the monophyletic nature of the Hermanella-Traverella complex. Previously weakly defined clades were also resolved based on the new evidence. In the species studied the egg chorionic structures as well as their shape did not change after oviposition or water immersion, remaining constant through the different maturation stages of each species (mature nymph, subimago, and imago). For this reason, the eggs are a valuable source of information to unambiguously identify and associate a nymph to its correspondent adult stage when rearing is not possible.
Asunto(s)
Corion/ultraestructura , Insectos/clasificación , Insectos/embriología , Óvulo/ultraestructura , Filogenia , Animales , Corion/anatomía & histología , Corion/fisiología , Insectos/genética , Estadios del Ciclo de Vida , Microscopía Electrónica de Rastreo , Oviposición , Óvulo/fisiologíaRESUMEN
Se presenta el caso clínico de una paciente a la cual se le diagnostica la presencia de gemelos fusionados en el 3er. trimestre del embarazo. Se obtienen por operación cesárea, gemelos craniopagus y tóracopagus tipo Janiceps. Se hace énfasis en la importancia de poder predecir y determinar sonográfica y tempranamente el tipo de corion que acompaña a cada embarazo gemelar, pues como ocurre en los gemelos fusionados, donde la placentación es monocoriónica, la probabilidad de complicaciones es mucho mayor, y la mortalidad de los gemelos monocoriónicos alcanza el doble de los gemelos dicoriónicos