摘要:

AbstractPdn/Pdnfetuses show preaxial Polydactyly of duplicated or triplicated metacarpal/metatarsal type in the fore‐ and hindlimbs.Pdn/+ fetuses show one extra digit of distal phalangeal type preaxially in the hindlimb and deformity of distal phalanx of the 1st digit in the forelimb. Normal patterns of physiological cell death in the preaxial apical ectodermal ridge (AER) and the deep preaxial mesoderm (fpp) were disrupted inPdn/Pdnembryos. It was supposed that delayed involution of preaxial AER might have caused the abolishment of fpp, which in turn could have induced polydactyly inPdn/Pdn.In order to induce cell death in the fpp region artificially, tissue destruction of the fpp region of right fore‐ and hindfoot plates ofPdn/Pdn,Pdn/+ and +/+ embryos was performed by an electric knife on day 11.5 of gestation, and the embryos were cultured in the rotator culture system for 20 hours. The non‐treated left foot plates served as the controls.InPdn/Pdnembryos, the non‐treated left foot plates showed abnormal protuberance and/or the extra digital rays preaxially. But the treated right foot plates did not exhibit these abnormal characteristics. Instead they revealed 5 digital rays of mesodermal condensation in the histological sections.These results indicated that the restriction of the artificial tissue destruction in the fpp region could prevent the manifestation of preaxial extra digits in

ISSN:0914-3505    

DOI:10.1111/j.1741-4520.1986.tb00653.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractEarly morphogenetic changes of exencephaly induced by ochratoxin A (OA) were compared with those induced by concanavalin A (Con A) in mice in order to examine possible differences in the pathogenesis of neural tube defect. OA and Con A were administered to pregnant mice on day 7 of gestation, and the process of neural tube closure of embryos was observed at different times from 6 to 72 hours after treatment by SEM and light microscopy. In OA‐treated embryos, the cranial neural folds in the fore‐ and midbrains did not elevate and remained in the biconvex shape. The cellular changes were found in the neuroepithelium and surface ectoderm. Neural crest cells, which appeared at the lateral edges of the neural folds, were also involved in degeneration. In Con A‐treated embryos, the neural folds in the mid‐ and hindbrains elevated to assume the V shape, but remained wide open. The main cellular change was a degeneration of the primary mesenchyme underlying the neuroepithelium, resulting in a paucity of the supporting mesenchymal tissue.These findings suggest that the exencephalies produced by either OA or Con A are primarily due to non‐closure of the neural tube, but that the pathogenesis differs with each agent. Failure of neural tube closure in OA‐treated embryos appears to result from damage of the neuroepithelium and neural crest cells, whereas that in Con A‐treated embryos from damage of the prima

ISSN:0914-3505    

DOI:10.1111/j.1741-4520.1986.tb00654.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe currently applied means for detecting teratogens require evaluations in mammals. Since these studies are so time consuming and expensive, establishment of inexpensive and rapid screening system for detecting potential teratogens is needed. In order to assess the usefulness of theXenopusembryo for developmental toxicity testing, the effects of lead acetate on embryonic and larval development ofXenopus laeviswere examined. Exposure to lead acetate produced lethality and abnormality in embryos and larvae and dose‐dependency was also noted. Main abnormality after the exposure of embryos before the neurula stage was unfused neural tube with various degrees. This abnormality was mainly attributable to degeneration and desquamation of the epithelium of neural groove and neural plate region. Abnormality induced by the exposure of embryos and larvae after neurulation was mainly edema in the thorax and abnormal flexure of the body axis. Based on our data and those of other investigators, it is proposed thatXenopusembryo is a good candidate for a simple and effective test system to evaluate teratogen

ISSN:0914-3505    

DOI:10.1111/j.1741-4520.1986.tb00655.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe evaluation of multiple congenital anomalies requires several points.1. Definite diagnostic criteria of each malformation and its precise description are of importance in the diagnosis of malformation syndromes.2. Complete family studies improve the accuracy of diagnosis and provide us with valuable information in genetic counselling.3. The use of good reference books and computer‐aided diagnosing systems are effective measures.4. It is of great importance to circulate case documents, and to exchange information on the diagnosis, among clinical dysmorphologists.5. It is crucial to combine the alert clinician's eye and the epidemiologic approach for seeking etiologic associations.6. Animal models of human malformation syndromes contribute much toward deep understanding of deviated morphogenesi

ISSN:0914-3505    

DOI:10.1111/j.1741-4520.1986.tb00656.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe purpose of this symposium is to summarize the recent advance in the study of oro‐facial anomalies in human. An understanding of the normal events in the embryonic development of the face facilitates the study of oro‐facial and also cranio‐facial anomalies. Embryological studies have revealed that the neural crest plays a major role in normal development of the face. The deficient formation, migration and proliferation in the neural crest cells and their derivatives around the cephalic region may be involved in defects of these structures. Observations of normal and abnormal human embryos are basically important, and a newly developed manipulation technique of cultured animal embryos and fetuses may provide us an effective information on the teratogenesis. In addition to the facial cleft, a special attention has been paid to the 1st and 2nd branchial syndromes. Associated anomalies with oro‐facial defects, especially those of midline structure including the brain may provide us the knowledge on tissue interaction in the morphogenesis and on therapeutic consideration. Since a higher frequency of cleft lip and palate among Japanese infants was reported, epidemiological data have to be analysed to search etiological factors, i.e., genetic and environmental factors. We realized, in this symposium, we could have a communication between the basic and clinical sciences on oro‐facial

ISSN:0914-3505    

DOI:10.1111/j.1741-4520.1986.tb00657.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractA monitoring of birth defects based on systematic collection and accumulation of data in a defined population or selected hospitals using definite diagnostic criteria offers per se indispensable source of information for epidemiological studies such as retrospective case‐control study or prospective cohort study.Each results of statistics or monitorings of birth defects currently conducted in Japan were briefly stated.The on‐going investigation data on congenital malformations about over 1,524,700 births performed since 1972 by Japan Association for Maternal Welfare were reviewed. Osaka and Kanagawa Programs, population‐based, have so far totally over 181,000 and 160,000 births resp.Factors increasing malformations suggested were stillbirth, low birth weight, small for gestational dates, consanguinity and smoking during pregnancy from Kanagawa Program. As an example of on‐going international collaborative study by the members of ICBDMS, data have been collected on limb reduction deformities. However, it might be more standardized in various aspects.Three statistical techniques — Z‐test, cusum test and sequential method were adapted to distinguish a significant increase from a baseline frequency or to identify significant temporal changes. Although abrupt fluctuations were encountered, overall patterns about 17 marker‐defects revealed to be fairly stationary in these years.Collection of sufficient numbers of cases and controls or exposed and unexposed enough to detect significantly so far unknown complicated factors is not always easy. To clarify unknown factors (polygenic, multifactorial, synergism or spontaneous errors of development), co‐work or co‐ordinated study of epidemiology and experimental teratology would be desirable to fill the

ISSN:0914-3505    

DOI:10.1111/j.1741-4520.1986.tb00658.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

ISSN:0914-3505    

DOI:10.1111/j.1741-4520.1986.tb00659.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

ISSN:0914-3505    

DOI:10.1111/j.1741-4520.1986.tb00652.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY