摘要:

Abstract1. A systematic analysis of the relation between 2 parameters of developmental stage — clinically assessed embryonic age and growth — was made for 90 human embryos at Carnegie stages 7–13 from healthy pregnancies. 2. The data showed remarkable individual variation in the relation between age and developmental stage of embryos at stages 11–13. It appears that the mean age for these stages in our specimens was a few days greater than the corresponding age in the currently cited standards, although a definite conclusion must await further studies. 3. The relation between body length and developmental stages in our embryos was not different from the corresponding standards presented by previous investigators. The relation of the number of somites to developmental stage and greatest length in 13 embryos at stages 9–11 was approximately in accord with that reported for several corresponding embryos by other investigators. 4. The oldest age for embryos at each stage in our data may have practical use in denying a causal relation between the exposure of pregnant women to an exogenous agent at such a stage and the subsequent appearance of specific malformations in thei

ISSN:0040-3709    

DOI:10.1002/tera.1420100102

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

年代:1974

数据来源: WILEY

ISSN:0040-3709    

DOI:10.1002/tera.1420100103

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

年代:1974

数据来源: WILEY

摘要:

AbstractA latent infection in the genital tract could explain epidemiological features of neural‐tube defects. Two of these features — a strong association with socioeconomic conditions and a low incidence in Jews — are also found in carcinoma of the cervix. It therefore seemed possible that herpesvirus type 2 might be causally related to neural‐tube defects. This hypothesis was tested by estimating neutralizing antibodies to herpesvirus types l and 2 in 125 women who had given birth to a child with a neural‐tube defect (anencephaly, spina bifida, or encephalocele) and 125 women similar in age, socioeconomic Status, and parity, who had had a child without a neural‐tube defect. In the event, it was found that mothers of defective children had a lower prevalence of neutralizing antibody to herpesvirus, especially type 1, than had the mothers of norm

ISSN:0040-3709    

DOI:10.1002/tera.1420100104

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

年代:1974

数据来源: WILEY

摘要:

AbstractSubcellular events during soft palate closure in hamsters were studied electron microscopically. In the early stages the surface epithelium of the palatal shelves was 2–3 cell‐layers thick and was separated from the underlying mesenchyme by an intact basal lamina. The epithelial cells contained few cytoplasmic organelles and were attached to each other by desmosomes. During further development tonofilaments and lysosomes appeared in the epithelial cells. Prior to fusion the epithelia of the opposing shelves displayed thickening followed by desquamation of the superficial cells. Fusion occurred by means of newly formed desmosomes between the fresh surfaces of the opposing epithelia of the shelves, thereby forming an epithelial seam bounded on each side by the basal lamina. Subsequent thinning and fragmentation of the seam occurred as a result of autophagy, exfoliation, and extrusion of cells through the intercellular spaces. Macrophages appeared at a later stage of soft palate development and removed the cellular debris. At no time during these stages of palatogenesis was there evidence of penetration of the basal lamina on either side of the epithelial seam by the surrounding mesench

ISSN:0040-3709    

DOI:10.1002/tera.1420100105

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

年代:1974

数据来源: WILEY

摘要:

AbstractVarious malformations and anomelies were induced in fetuses of mice parabiotically joined on the 6th, 7th, or 8th day of pregnancy and in fetuses of crowded pregnant mice. Mice were crowded by placing them 18/cage (dimensions 7″ × 7″ × 10″ ) on days 3–4 of pregnancy. The abnormalities included amputation of peripheral limb structures, open neural folds, exencephaly, blisters, head, face, and tail malformation, and generalized growth retardation. The hypothesis that the teratogenic and other effects were consequences of prolonged prenatal stress induced by the experimental conditions is supported by the observation that both procedures led in a short time to significant increases in mean maternal adren

ISSN:0040-3709    

DOI:10.1002/tera.1420100106

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

年代:1974

数据来源: WILEY

摘要:

AbstractSingle injections of 100 μg of 5‐fluorouracil (5‐FU) containing 1.25 μc of [2‐14C]5‐FU were made into the yolk sac of 4‐day chick embryos. Greater amounts of label were incorporated into DNA than into RNA extracts. The rate of accumulation of protein per embryo was lowered by 5‐FU to a somewhat greater extent than was either DNA or RNA. Chromatography of TCA‐soluble fraction from 5‐day embryos indicated presence of 5‐FU and two peaks of unidentified heavier molecules derived from 5‐FU. Thus the selective depression of protein accumulation and the progressive labeling of DNA from 5‐FU indicate a wider spectrum of metabolic effects in chick embryos than might be expected from the reports of 5‐FU in the literature. These data suggest that 5‐FU may act as a teratogen by one or more routes other than as an a

ISSN:0040-3709    

DOI:10.1002/tera.1420100107

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe course of secondary‐palate closure was studied in control, cortisone‐, and 6‐azauridine‐treated randombred H‐Velaz mice. The size of the gap between the developing palatal processes and wet fetal weight were used as measures of secondary‐palate development and overall fetal development. It was found that 250 mg of 6‐azauridine injected im on day 14 both retarded the rate of fetal development and delayed initiation of horizontalization of palatal processes with regard to developmental age of fetuses; and that 7.5 mg of cortisone acetate injected im on day 12 affected the progress of horizontalization rather than its initiation. The mean distance between ihe medial edges of the palatine processes was significantly higher in cortisone‐treated fetuses than in controls just before horizontalization. According to this finding the supposed discrepancy between the width of the head and the palatal processes (resulting in absolute or relative narrowness of palatal processes when they beccme horizontal) is present, at least in part, even before ho

ISSN:0040-3709    

DOI:10.1002/tera.1420100108

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe main uterine vessels of pregnant rats were clamped on day 14 for 30, 60, or 90 min. The fetal death rate was increased by 60 or 90 min clamping, proportional to duration. Some surviving fetuses showed skeletal retardation, bilateral limb anomalies, and cleft palate when examined on day 21. As early as 3 h after declamping, edema was seen in the mesenchymal tissue of the limbplates, together with a marked dilatation of the fetal vessels. Later this tissue became necrotic. The necrotic changes also involved surrounding mesenchyme including developing bone, which resulted in the observed limb malformations. In addition large blisters and hematomas at the tip of the snout may have caused tongue displacement to such an extent that palate closure was mechanically impaired. The malformations thus apparently resulted secondarily from necrosis of mesenchymal tissues that had been fully differentiated. This pathogenesis may be a common one for various malformations after impairment of fetal nutrition in rats at this particular develop mental stage.

ISSN:0040-3709    

DOI:10.1002/tera.1420100109

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

年代:1974

数据来源: WILEY

摘要:

AbstractKittens, 4–9 days old, from untreated mothers, received oral daily doses of 0.25–1 mg/kg Hg (as CH3HgCl) for various periods. Those given 0.25 and 0.37 mg/kg exhibited no clinical toxicity. At 0.5 mg/kg one of 3 kittens developed toxicity signs after 77 days of treatment whereas the others appeared healthy after 111 and 184 days of dosing, respectively. Typical neurological signs of methylmercury poisoning appeared in all kittens after a mean of 63 days of 0.75 mg/kg and 48 days of 1 mg/kg treatment. In kittens developing toxicity signs brain Hg content was 19–26 μg/g but blood Hg content varied widely. The blood/brain Hg ratio was dose‐dependent and decreased with increasing dosage. Degenerative changes in granule cells, Purkinje cells, and cerebral neurons and distorted myelmalion in cortical hemispheres characteristic of methylmercury toxicosis were produced by all doses. TheT1/2of Hg in blood following single oral doses of CH3Hg203Cl was 32 ± 3 days in 4‐week‐old and 36 ± 3 days in 10‐week‐old kittens. The findings indicated that a higher daily dosage is required to produce clinical methylmercury poisoning in kittens

ISSN:0040-3709    

DOI:10.1002/tera.1420100110

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

年代:1974

数据来源: WILEY

ISSN:0040-3709    

DOI:10.1002/tera.1420100111

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

年代:1974

数据来源: WILEY