摘要:

AbstractThe effects of urethan on ICR/JCL mouse limbs were examined in forelimbs of day‐11 embryos cultured in concentrations of 0, 50, and 100 μg/ml for one to four days, and in forelimbs of day‐12 embryos and in fore‐ and hind limbs of day‐13 embryos in 0, 10, 50, and 100 μg/ml for one to four days. Urethan did not cause digital malformations in day‐11 limbs but induced syndactyly in day‐12 forelimbs and polydactyly in day‐12 forelimbs and day‐13 fore‐ and hind limbs. The polydactyly may have been due to effects on mesenchymal cells producing localized cell proliferation, whereas syndactyly may have been due to effects on precartilage cells, resulting in excess migration of mesenchymal cells toward the digits, leaving the connective tissue at the interdigital space to d

ISSN:0040-3709    

DOI:10.1002/tera.1420150112

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe crown‐rump length of 483 fixed human embryos of Carnegie stages 6–23 was analyzed and median and predicted mean lengths were calculated. The results were compared with those of other series and confirmed that early human growth rates are different from those of macaques with which human embryo growth has previously been compared. The study indicated that it is possible to predict: 1. the median size of an embryo of given Streeter horizon or Carnegie stage; 2. the age of a fresh embryo, or one of undisputed Streeter staging, by comparison with mean figures of other authorities; and 3. the corrected age of an embryo of known length or known Streeter staging or both in terms of postovulation age. Since teratogens may reduce the embryonic growth rate this information is relevant in the analysis of teratogenic factors in human developm

ISSN:0040-3709    

DOI:10.1002/tera.1420150113

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

年代:1977

数据来源: WILEY

摘要:

AbstractLinear measurements, total weights, and organ weights of 133 fresh human fetuses were obtained after therapeutic abortion between 90 and 170 days postmenses. Great apparent variation was observed in fetuses of given ages, especially in organ weights. There was no evidence of sex or parity differences.

ISSN:0040-3709    

DOI:10.1002/tera.1420150114

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

年代:1977

数据来源: WILEY

摘要:

AbstractRat embryos were explanted on day 8 or 9 of pregnancy and cultured for up to 48 hours in serum containing added retinol (vitamin A), retinoic acid (vitamin A acid), or absolute ethanol. They were examined morphologically and their protein content determined. Retinoic acid was more teratogenic and growthretarding than retinol. Electron microscopy of embryos cultured for 30 minutes or one hour revealed that both forms of vitamin A brought about similar ultrastructural effects on the embryonic cells; however, the abnormally large intracellular lipid droplets observed in a previous study following exposure to retinol in vitro and retinyl palmitate in vivo were not observed in embryos exposed to retinoic acid. It is possible that the differential teratogenicity may be due to the inability of the embryonic cells to convert and store retinoic acid in a less teratogenic form.

ISSN:0040-3709    

DOI:10.1002/tera.1420150115

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

年代:1977

数据来源: WILEY

摘要:

AbstractContact and fusion of the palatal processes are prevented by mechanical obstruction in A/J mice with spontaneous cleft lip and palate. Histological examination of cleft‐lip fetuses revealed a very thin epithelial covering on the tip of the palatal process at day 15 1/2 of gestation, when the palate normnlly undergoes fusion, but at day 16 the palatal epithelium was completely disrupted, exposing the underlying mesenchyme. This epithelial discontinuity lasted only one day — by day 17 epithelial continuity was reestablished. These findings support the hypothesis that contact between the palatal shelves is not a prerequisite for epithelial degenerat

ISSN:0040-3709    

DOI:10.1002/tera.1420150116

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

年代:1977

数据来源: WILEY

ISSN:0040-3709    

DOI:10.1002/tera.1420150117

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

年代:1977

数据来源: WILEY

ISSN:0040-3709    

DOI:10.1002/tera.1420150101

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

年代:1977

数据来源: WILEY