摘要:

AbstractThe common congenital malformations have familial distributions that cannot be accounted for by simple Mendelian models, but can be explained in terms of a continuous variable, “liability,” with a threshold value beyond which individuals will be affected. Both genetic and environmental factors determine liability, making the system multifactorial. Cleft palate is a useful experimental model, illustrating a number of factors that contribute to palate closure, the nature of a developmental threshold, and how genes and teratogens can alter the components of liability to increase the probability of cleft palate. The nature of the genetic component to liability in human malformations is not clear, and various possibilities, ranging from polygenic in the strict sense to a major gene with reduced penetrance are compatible with the data—but the important feature is the threshold. Much of the confusion over the concept results from inconsistent use of terminology. The term “multifactorial” should be used for “determined by a combination of genetic and environmental factors,” without reference to the nature of the genetic factor(s). “Polygenic” should be reserved for “a large number of genes, each with a small effect, acting additively.” When several genes, with more major effects are involved, “multilocal” can be used. When it is not clear which of these is applicable the term “plurilocal” is suggested, in the sense of “genetic variation more complex than a simple Mendelian difference,” Since teratological data often represent threshold characters the concept also has important implications for the interpretation of data on dose‐response curves, synergisms, and strain di

ISSN:0040-3709    

DOI:10.1002/tera.1420140302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1976

数据来源: WILEY

摘要:

AbstractEmbryos of a family of chickens homozygous for muscular dystrophy (md/md) reacted with a higher incidence of malformations to treatment with carbachol than did White Leghorn embryos. The same difference in response of embryos from the two stocks occurred after treatment with sulfanilamide. Embryos of reciprocal crosses between these two stocks differed greatly, however, in their response to carbachol, F1embryos from dystrophic hens producing a much higher incidence of malformations than did those from Leghorn hens. In contrast, both F1sibs reacted similarly to sulfanilamide, the teratogenic effects being intermediate between those of embryos from the parent stocks.

ISSN:0040-3709    

DOI:10.1002/tera.1420140303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1976

数据来源: WILEY

摘要:

AbstractExposure of fertilizedOryzias latipeseggs to concentrations of 2,4,5‒trichlorophenoxyacetic acid up to 14 ppm had no gross developmental effects. Exposure to concentrations above 14 ppm resulted in multiple malformations of the heart and blood vessels. Embryos failed to hatch when exposed to concentrations above 25 pp

ISSN:0040-3709    

DOI:10.1002/tera.1420140304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1976

数据来源: WILEY

摘要:

AbstractLateral and ventral graphic reconstructions of coronally sectioned rat fetuses at four stages of secondary palate development were made to illustrate the size, form, and spatial relations of craniofacial structures at each stage, and to indicate changes between stages. The results illustrated extensive changes in the nasomaxillary and tongue‐mandibular complexes and spatial relations in the oronasal cavity during this 2‐day period. During closure of the palate the palatine processes and molar dental laminae moved medially, the vertical dimension between the cranial base and Meckel's cartilage increased, and the Meckel's cartilage changed in shape from a “U” to a “V.” During the 2‐day period extensive increases in anteroposterior and vertical dimensions and limited changes in lateral dimensions resulted in a change in shape of the complete orofacial region. More extensive investigations, preferably quantitative, of the changes shown are indicated to identify the relative contribution of various craniofacial components and to establish the role of differential growth in secondary p

ISSN:0040-3709    

DOI:10.1002/tera.1420140305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1976

数据来源: WILEY

摘要:

AbstractEctopic pregnancy in the fallopian tube occurs in about 1 in 50 human pregnancies. Maternal factors in the etiology of this condition have been well documented. There is less information available on the development of the embryo or fetus. To document this information morphological and cytogenetic data were obtained from 76 embryos and fetuses obtained from pregnancies occurring in the fallopian tube. Analysis of the data showed that tubal implantation was associated with a high proportion of severely disorganized embryos. There was also a high incidence of maternal tubal disease. The importance of these factors and the etiology of ectopic pregnancy is discussed.

ISSN:0040-3709    

DOI:10.1002/tera.1420140306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1976

数据来源: WILEY

摘要:

AbstractExposure of pregnant hamsters on gestation day 8 to 40 or 41°C for one hour caused an increased rate of resorption and a high frequency of exencephaly and encephatocele. Longer exposures often killed pregnant females. Hamsters that had fetuses with abnormalities usually experienced body temperature elevations of 3‒4°C above normal (37

ISSN:0040-3709    

DOI:10.1002/tera.1420140307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1976

数据来源: WILEY

摘要:

AbstractIn a longitudinal study including measurement of the pressure in the amniotic cavity, amniotomy, and planimetric evaluation of the size of the amniotic sac, we investigated the development of the “strait jacket” syndrome in White Leghorn chicken embryos injected intraamniotically (ia) or paraamniotically on the fourth day of incubation with histone or embryotoxic serum, with the following results. Hyperlordosis and eventration developed as an outcome of tonic contraction of the amnion, which was observed only three hours after ia administration. Contraction of the amnion caused elevation of the intraamniotic pressure, which, 12 hours after ia injection, attained a mean value of 22,4 Pa (2.3 mm H2O). This value was not only significantly higher than the mean for control embryos (3.9 Pa), but it was critically close to the mean fluid pressure in thehrain vesicles. Loss of the latter overpressure caused the vesicles to collapse, and the walls shriveled and exencephaly developed, Paraamniotic injection was not followed by either contraction of the amnion, or significant increase in intraamniotic pressure. This did not prevent, heart malformations and cranioschisis of various extent. The majority of cardiovascular malformations were probably the hemodynamic consequence of overfilling of the intraembryonic vascular bed, which was one of the early signs of the effect in question. Cranial‐vault defects can be causally associated with the formation of amnionic adhesion and fusion with the epidermal ectoderm. This observation stresses the significance of the embryonic membranes and the fluid pressures within them for the development of certain congenital deformities and concentrates attention on teratological study of substances that induce protracted contraction of smooth m

ISSN:0040-3709    

DOI:10.1002/tera.1420140308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1976

数据来源: WILEY

摘要:

AbstractThe embryotoxic properties of an ethanol extract of boiled potatoes infected withPhytophthora infestanswere investigated in White Leghorn chicken embryos, using controlled subgerminal injection on the second day of incubation and intraamniotic injection on the third and fourth days. A dose of 0.3 mg of sublimation‐dried extract interfered at the somite stages with the function of the caudal morphogenetic system and induced various degrees of the caudal regression syndrome. Administration on the third and fourth days led to the development of a malformation syndrome comprising cranioschisis, celosoma, and cardiac septal defects. An equivalent amount of extract of healthy potatoes of the same variety and injection of pure solanine had the same effect. The results warrant the claim that the main factor responsible for the direct embryotoxicity of potatoes attacked byP. infestansis solanine, which evokes tonic contract ion of the smooth muscle elements of the amnio

ISSN:0040-3709    

DOI:10.1002/tera.1420140309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1976

数据来源: WILEY

摘要:

AbstractDay 17.5 yolk sacs from rats injected with partially denatured125I‐labeled bovine serum albumin (I‐BSA) were cultured in vitro by a raft technique. The rates of release of [125I] iodotyrosine were similar in control yolk sacs and in yolk sacs from rats preinjected with trypan blue. Day 17.5 rat yolk sacs were also cultured in medium containing I‐BSA. Following pinocytic uptake the substrate was degraded intracellularly and [125I]iodotyrosine released into the medium. Trypan blue, when present in the medium in concentrations above 100 üg/ml, inhibited pinocytosis of I‐BSA and so decreased the rate of [125I]iodotyrosine production. Trypan blue similarly decreased the rate of pinocytic uptake of125I‐labeled polyvitiylpyrrolidone. Pinocytic uptake of macromolecules was not decreased in yolk sacs from rats pretreated with trypan blue. The relevance of these results to the mechanism of teratogenic action of trypan blue is discussed. It is proposed that if trypan blue in teratogenic doses similarly inhibits pinocytosis by the yolk sac during the organogenetic period teratogenests might result from a transient interruption in the flow of metabolites through the yolk sac to

ISSN:0040-3709    

DOI:10.1002/tera.1420140310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1976

数据来源: WILEY

ISSN:0040-3709    

DOI:10.1002/tera.1420140311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1976

数据来源: WILEY