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Early Fetal Life (early + fetal_life)
Selected AbstractsFacial surface analysis by 3D laser scanning and geometric morphometrics in relation to sexual dimorphism in cerebral,craniofacial morphogenesis and cognitive functionJOURNAL OF ANATOMY, Issue 3 2005Robin J. Hennessy Abstract Over early fetal life the anterior brain, neuroepithelium, neural crest and facial ectoderm constitute a unitary, three-dimensional (3D) developmental process. This intimate embryological relationship between the face and brain means that facial dysmorphogenesis can serve as an accessible and informative index of brain dysmorphogenesis in neurological and psychiatric disorders of early developmental origin. There are three principal challenges in seeking to increase understanding of disorders of early brain dysmorphogenesis through craniofacial dysmorphogenesis: (i) the first, technical, challenge has been to digitize the facial surface in its inherent three-dimensionality; (ii) the second, analytical, challenge has been to develop methodologies for extracting biologically meaningful shape covariance from digitized samples, making statistical comparisons between groups and visualizing in 3D the resultant statistical models on a ,whole face' basis; (iii) the third, biological, challenge is to demonstrate a relationship between facial morphogenesis and brain morphogenesis not only in anatomical,embryological terms but also at the level of brain function. Here we consider each of these challenges in turn and then illustrate the issues by way of our own findings. These use human sexual dimorphism as an exemplar for 3D laser surface scanning of facial shape, analysis using geometric morphometrics and exploration of cognitive correlates of variation in shape of the ,whole face', in the context of studies relating to the early developmental origins of schizophrenia. [source] Development of the genital ducts and external genitalia in the early human embryoJOURNAL OF OBSTETRICS AND GYNAECOLOGY RESEARCH (ELECTRONIC), Issue 5 2010Yasmin Sajjad Abstract The course of development of the human genital tract is undifferentiated to the 9th week of development. At this time two symmetrical paired ducts known as the mesonephric (MD) and paramesonephric ducts (PMD) are present, which together with the urogenital sinus provide the tissue sources for internal and external genital development. Normal differentiation of the bipotential external genitalia and reproductive ducts are dependent upon the presence or absence of certain hormones. Masculinization of the internal and external genitalia during fetal development depends on the existence of two discrete testicular hormones. Testosterone secreted from Leydig cells induces the differentiation of the mesonephric ducts into the epididymis, vasa deferentia and seminal vesicles, whereas anti-Müllerian hormone (AMH) produced by Sertoli cells induces the regression of the paramesonephric ducts. The absence of AMH action in early fetal life results in the formation of the fallopian tubes, uterus and upper third of the vagina. In some target tissues, testosterone is converted to dihydrotestosterone, which is responsible for the masculinization of the urogenital sinus and external genitalia. [source] A study of inherited short tail and taillessness in Pembroke Welsh corgiJOURNAL OF SMALL ANIMAL PRACTICE, Issue 5 2008A. Indrebř Objectives: To study whether natural short tail in adult Pembroke Welsh corgi is associated with congenital spinal defects. To report anatomical defects in two newborn tailless puppies from short-tailed parents, and to check whether they were homozygous for the dominant mutation in the T-gene (C295G). Methods: The vertebral column of 19 adult dogs with natural short tail, from short-tail×long-tail crossings, was radiographically examined. Two tailless puppies were radiographed and submitted for necropsy. Samples from the puppies, their parents and five siblings were analysed for the mutation of the T-gene. Results: No congenital spinal defects were diagnosed in any of the short-tailed dogs. The tailless puppies had anorectal atresia, had multiple spinal defects and were homozygous for the mutation in the T-gene. Clinical Significance: As tail docking is forbidden in many countries, breeding Pembroke Welsh corgis with natural short tail is becoming increasingly common. Previous studies indicated that the mutation in homozygotes is lethal in early fetal life. It is of clinical significance that natural short tail is probably not associated with congenital spinal defects, as is known from studies of other species, and that homozygotes for this mutation with serious anatomical defects may be born. [source] Characteristics of testicular dysgenesis syndrome and decreased expression of SRY and SOX9 in Frasier syndromeMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 9 2008Valérie Schumacher Abstract Frasier syndrome (FS) is characterized by chronic renal failure in early adulthood, varying degrees of gonadal dysgenesis, and a high risk for gonadal germ cell malignancies, particularly gonadoblastoma. Although it is known to arise from heterozygous splice mutations in intron 9 of the Wilms' tumor gene 1 (WT1), the mechanisms by which these mutations result in gonadal dysgenesis in humans remain obscure. Here we show that a decrease in WT1,+,KTS isoforms due to disruption of alternative splicing of the WT1 gene in a FS patient is associated with diminished expression of the transcription factors SRY and SOX9 in Sertoli cells. These findings provide the first confirmation in humans of the results obtained by others in mice. Consequently, Sertoli cells fail to form the specialized environment within the seminiferous tubules that normally houses developing germ cells. Thus, germ cells are unable to fully mature and are blocked at the spermatogonial,spermatocyte stage. Concomitantly, subpopulations of the malignant counterpart of primordial germ cells/gonocytes, the intratubular germ cell neoplasia unclassified type (ITGCN), are identified. Furthermore, dysregulated Leydig cells produce insufficient levels of testosterone, resulting in hypospadias. Collectively, the impaired spermatogenesis, hypospadias and ITGCN comprise part of the developmental disorder known as ,testicular dysgenesis syndrome' (TDS), which arises during early fetal life. The data presented here show that critical levels of WT1,+,KTS, SRY and SOX9 are required for normal Sertoli cell maturation, and subsequent normal spermatogenesis. To further study the function of human Sertoli cells in the future, we have established a human cell line. Mol. Reprod. Dev. 75: 1484,1494, 2008. © 2008 Wiley-Liss, Inc. [source] Active and passive maternal smoking during pregnancy and the risks of low birthweight and preterm birth: the Generation R StudyPAEDIATRIC & PERINATAL EPIDEMIOLOGY, Issue 2 2008Vincent W. V. Jaddoe Summary The objective of this study was to examine the associations between active and passive smoking in different periods of pregnancy and changing smoking habits during pregnancy, with low birthweight and preterm birth. The study was embedded in the Generation R Study, a population-based prospective cohort study from early fetal life onwards in Rotterdam, The Netherlands. Active and passive smoking were assessed by questionnaires in early, mid- and late pregnancy. Analyses were based on 7098 pregnant women and their children. Active smoking until pregnancy was ascertained and was not associated with low birthweight and preterm birth. Continued active smoking after pregnancy was also recorded and was associated with low birthweight (adjusted odds ratio 1.75 [95% CI 1.20, 2.56]) and preterm birth (adjusted odds ratio 1.36 [95% CI 1.04, 1.78]). The strongest associations were found for active maternal smoking in late pregnancy. Passive maternal smoking in late pregnancy was associated with continuously measured birthweight (P for trend <0.001). For all active smoking categories in early pregnancy, quitting smoking was associated with a higher birthweight than continuing to smoke. Tendencies towards smaller non-significant beneficial effects on mean birthweight were found for reducing the number of cigarettes without quitting completely. This study shows that active and passive smoking in late pregnancy are associated with adverse effects on weight and gestational age at birth. Smoking in early pregnancy only, seems not to affect fetal growth adversely. Health care strategies for pregnant women should be aimed at quitting smoking completely rather than reducing the number of cigarettes. [source] | |||||||||||||