1,720,998 research outputs found
Sul test di esclusione del colore. - II Influenza di sostanze macromolecolari neutre. [On the dye exclusion test of cell vitality. II. Influence of neutral macromolecular substances.]
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Sul test di esclusione del colore. - I Valutazione della concentrazione ottimale [On the dye exclusion of test cell vitality. I. Evaluation of the optimal concentration]
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Emx2 developmental expression in the primordia of the reproductive and excretory systems
No full textThe development of the urogenital system hasalways attracted many investigators owing to the peculiaraspects of the embryology of the reproductive and excretoryorgans and to the high number of congenital anomaliesrelated to these structures. It is remarkable becauseof the common origin of the kidneys, gonads, and genitaltracts from the intermediate mesoderm and because differentiation of these organs involves extensive mesenchymeto epithelium transition. Our knowledge about themolecular mechanisms controlling the differentiation ofthese diverse structures from the same precursor has takenadvantage of gene expression data and gene-targetingexperiments using genes with a specific expression patternin the urogenital system. A more detailed functionin kidney development has been postulated for transcriptionfactors such as WT-1, Pax-2 or other molecules suchas glial cell line-derived neurotrophic factor (GDNF),Wnt-4, c-ret. In the present work we have described theexpression pattern of the homeobox-containing geneEmx2 during the development of the urogenital system inmouse embryos. We have found that Emx2 is expressedin the early primordia of the organs that will form the excretoryand reproductive systems. In particular we havefound that Emx2 is expressed in the epithelial componentsof pronephros and mesonephros, in Wolffian andMüllerian ducts, in the ureteric buds with their branchesand in the early epithelial structures derived from metanephrogenic mesenchyme. Emx2 is also intensely expressedin the “bipotential” or “indifferent” gonads andovaries. These data and the recent finding that Emx2 homozygousmutant mice die soon after birth because ofthe absence of kidneys indicate an essential role of Emx2in the morphogenesis of the urogenital system
Incidence of non-age-dependent chromosomal abnormalities: a population-based study on 88965 amniocenteses
No full textCurrent knowledge about the incidence of chromosomal abnormalities in the general population comes from studies in newborns carried out in the 70s, before the era of widespread prenatal diagnosis. In the following years, data on frequency of chromosomal abnormalities in the second trimester of pregnancy have been used in conjunction with the data on the natural history of chromosomally abnormal fetuses to infer maternal age-specific rates of cytogenetic abnormalities in live-born infants. Starting from the data gathered in 1995-1996 from all Italian cytogenetic laboratories (with 92% compliance to the study), we have compared the frequency of chromosomal abnormalities at amniocentesis in cases with maternal age of >or=35 years (51,758 individuals) and cases with maternal age of <35 years (37,207 cases). The comparison confirmed the age-dependency of aneuploidies, whereas none of the structural abnormalities showed age-related differences. Furthermore, among the mosaic aneuploidies, trisomy 21 and 45,X/46,XX were found with a significantly higher incidence in older women. Chromosomal abnormalities that showed no significant difference between the two groups were summed for the overall national cohort, providing a general estimate of the incidence in the second trimester of pregnancy. The data provide critical background information for prenatal genetic counseling and for the planning of health care policy
Developmental Pathways Of Vertebral Centra And Neural Arches In Human Embryos And Fetuses
No full textThe ossification pathways of both vertebral centra (i.e., vertebral bodies) and neural arches were studied in human embryos and fetuses (CR-length between 38 and 116 mm). A clearing and double-staining method for whole embryo or fetus, using alcian blue and alizarin red S, allowed an easy and precise detection of the morphology of the whole vertebral column and every single vertebra. Both cartilaginous and bony components were clearly visible. Different temporal and topographical patterns of ossification were shown for the centra and arches; the latter were respectively proximal-distal (i.e., bidirectional from a defined starting tract in T10-L1) and cranial-caudal (i.e., monodirectional). The patterns could be related to the morphogenetic processes of other structures (i.e., muscles and nerves). Moreover, the numerical survey of ossification centers provided a possible parameter for the determination of the fetal developmental age. This could be useful in the study of pathological conditions
Agenesis of the scapula in Emx2 homozygous mutants
Full text linkThe shoulder and pelvic girdles represent the proximal bones of the appendicular skeleton that connect the anterior and posterior limbs to the body trunk. Although the limb is a well-known model in developmental biology, the genetic mechanisms controlling the development of the more proximal elements of the appendicular skeleton are still unknown. The knock-out of Pax1 has shown that this gene is involved in patterning the acromion, while the expression pattern candidates Hoxc6 as a gene involved in scapula development. Surprisingly, we have found that scapula and ilium do not develop in Emx2 knock-out mice. In the homozygous mutants, developmental abnormalities of the brain cortex, the most anterior structure of the primary axis of the body, are associated with important defects of the girdles, the more proximal elements of the secondary axis. These abnormalities suggest that the molecular mechanisms patterning the more proximal elements of the limb axis are different from those patterning the rest of appendicular skeleton. While Hox genes specify the different segments of the more distal part of the appendicular skeleton forming the limb, Emx2 is concerned with the more proximal elements constituting the girdles
Familial Beckwith-Wiedemann syndrome due to CDKN1C mutation manifesting with recurring omphalocele
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Molecular cloning and fine mapping of API5L1, a novel human gene strongly related to an antiapoptotic gene
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