摘要:

AbstractThe isolated mammalian embryo is a relatively unexploited developmental system for studying early somite stages: the embryonic period of greatest susceptibility to teratogenesis. The mouse embryo offers sufficient advantages for such studies that a short‐term culture procedure was adapted for early postimplantation stages (Witschi stages 14 or 15 corresponding to one to 12 somites). Criteria for growth in vitro demonstrated that quantitative determinations of DNA, RNA and protein content consistently correlated with morphological end points.A medium comprising 20% rat serum in Waymouth's MB 752/1 supported better development and net macromolecular synthesis than did media containing 0, 10 or 100% rat serum. Embryos in the 20% serum‐supplemented medium approximately doubled their nucleic acid and protein contents during 22 hours in culture. This increase corresponds to roughly 60% of the growth of embryos in vivo and should permit biochemical investigations to be made of the early effects of teratogenic treatme

ISSN:0040-3709    

DOI:10.1002/tera.1420020302

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

年代:1969

数据来源: WILEY

摘要:

AbstractNormal pregnant guinea pigs were killed on gestation days 12–20 and examined for implantation sites and resorbing embryos. Their ovaries were removed and serially sectioned, and the functioning corpora lutea counted for comparison with the number of conceptuses.It was found that a single corpus luteum was associated with two implantation sites with a frequency of 9.55%. Embryonic loss prior to implantation was 12.6% and the value for resorption following implantation varied from 5.8 to 7.2% depending on the time of killing and the method employed for determining resportion. A count of functioning corpora lutea facilitated the determination of embryonic loss prior to implantation, but offered little advantage over simpler techniques for determining resorption after implantatio

ISSN:0040-3709    

DOI:10.1002/tera.1420020303

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

年代:1969

数据来源: WILEY

摘要:

AbstractPrevious experiments on palate development led to the hypothesis that neck extension and movements of the lower jaw and tongue are necessary for palate closure. To see if such movements existed at the appropriate developmental stage living embryos were studied at the time of normal palate closure. Spinal cord sections were performed on pregnant mice to permit laparotomy without sedating the embryos, the mice were partially submerged in warm saline, and embryonic movements were observed and photographed. Onset of movement coincided temporally with the onset of palate closure. In addition to movements of limbs and trunk, movements of neck, lower jaw, and tongue were also seen. Activity of embryos could be detected within the intact uterus as well as after removal from the uterus and membranes, and was inhibited by ether. The movements appeared to be spontaneous. These observations are consistent with the hypothesis that the mechanism of palate closure involves muscular movements by the embryo.

ISSN:0040-3709    

DOI:10.1002/tera.1420020304

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

年代:1969

数据来源: WILEY

摘要:

AbstractMethylbis(beta‐chloroethyl)amine hydrochloride was applied for 1 minute to the slit vitelline membrane over different mediolateral portions of ribforming levels of 22‐ to 27‐somite chick embryos by uniformly prepared agar discs of uniform dimensions. Gross effects on rib patterns and external features (body wall, feather tracts, wings) were recorded after 10 to 11 days of incubation.Rib patterns were essentially normal in most specimens with agar discs placed over the right lateral plate only; modifications of external features other than right wings were minimal under these circumstances. Placement of agar discs close to or over any portions of the somites and also over the lateral plate resulted in modifications both of rib patterns and external features. Related modifications occurred in vertebral and sternal components of ribs 3–7. Vertebral components were reduced in size, otherwise modified, or absent. Sternal components were either modified correspondingly, usually to greater degrees, or absent. Sternal components never formed in the absence of corresponding vertebral components. Similar modifications of vertebral and sternal components sometimes occurred on the left side when agar discs were applied to the right side. Modified external features (transverse grooves or depressions, body foreshortening, dorsal displacement and other modifications of breast and ventral feather tracts) appeared to be due to reduction of body musculature.These results are compatible with the classical hypothesis that vertebral and sternal rib components and ventrolateral muscles originate exclusively from

ISSN:0040-3709    

DOI:10.1002/tera.1420020305

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

年代:1969

数据来源: WILEY

摘要:

AbstractA histological study of the action of cortisone on developing chick embryo tibial cartilage revealed that the chondrocytes were smaller and the intercellular substance was diminished. Autoradiographic experiments demonstrated less accumulation of35S in the diaphysis of cortisone‐treated cartilage, but not in the metaphysis or epiphysi

ISSN:0040-3709    

DOI:10.1002/tera.1420020306

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

年代:1969

数据来源: WILEY

摘要:

AbstractPregnant DBA/2J, C3H/HeJ, and ICR/Ha mice were injected intraperitoneally with vincristine sulfate on day 9 of gestation. The mothers were killed on day 17 and the fetuses were examined for various defects. A high incidence of fetal mortality, congenital anomalies, and growth retardation was induced in all three types of mice. DBA's were most susceptible to the teratogenic effects of the drug. Anomalies involved the central nervous system, eyes, limbs, tail and ribs, and most fetuses had more than one anomaly. Most of the types of anomalies observed were similar to those reported in rats, but dose required to produce malformations was much higher than that reported for rats, hamsters and monkeys.

ISSN:0040-3709    

DOI:10.1002/tera.1420020307

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

年代:1969

数据来源: WILEY

摘要:

AbstractFetal weight data from 28 litters of Wistar rats were analyzed for the effect of position in the uterine horn on fetal weight. The deviation of each fetus from the mean weight of all fetuses in a uterine horn was divided by the standard deviation of the mean. The standard scores thus obtained were studied for position effect. A pattern of fetal weights was found in which the heaviest fetus occupied the middle position with a progressive decrease in weights toward the ovarian and cervical ends of the horn. The lightest fetus in each horn was most likely to be found occupying either one of these extreme positions. These results are discussed with respect to a hemodynamic theory of fetal growth control that has been postulated for the guinea pig and mouse, and it is concluded that this theory is not applicable to the normal rat pregnancy.

ISSN:0040-3709    

DOI:10.1002/tera.1420020308

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

年代:1969

数据来源: WILEY

ISSN:0040-3709    

DOI:10.1002/tera.1420020310

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

年代:1969

数据来源: WILEY

ISSN:0040-3709    

DOI:10.1002/tera.1420020311

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

年代:1969

数据来源: WILEY

ISSN:0040-3709    

DOI:10.1002/tera.1420020312

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

年代:1969

数据来源: WILEY