摘要:

AbstractAccessory spleens in 2 separate necropsy series of (a) 1848 randombred rabbits and (b) 21,802 inbred and partially inbred and 880 hybrid rabbits were described and illustrated. The overall frequency in the randombred population (8.9%) was comparable to that in unselected human necropsy series (10%). The predominant locations of accessory spleens in the rabbits (adjacent to the splenic hilus, the gastrosplenic ligament, and the tail of the pancreas) arranged in descending order, were comparable to their locations in human beings. The inbred rabbits had an overall frequency of at least one accessory spleen of 22.5%, similarly located, and ranged from 1–50%, depending on the strain. It was shown by crosses of high‐ and low‐frequency strains that the presence of accessory spleens is due in part to genetic factors and that a high frequency of accessory spleens is probably a recessive characteristic. The latter interpretation is also supported by the fact that the low or “normal” strains had an overall frequency of at least 1 accessory spleen of 8.8% which is in accord with both the randombred rabbit population and human necropsy

ISSN:0040-3709    

DOI:10.1002/tera.1420130302

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

年代:1976

数据来源: WILEY

摘要:

AbstractAnalysis of several inbred strains of rabbits with high (30–50%) frequencies of accessory spleens revealed that hereditary hematological diseases, autoimmune hemolytic anemia and lymphosarcoma, occurred in some of them. Twenty‐one per cent of individuals in these strains, though phenotypically normal, had globulin‐coated (Coombs'‐positive) erythrocytes. These findings supported observations of increased frequency of accessory spleens in human beings with similar diseases (e.g., autoimmune hemolytic anemia, idiopathic thrombocytopenic purpura, “secondary hypersplenism,” Gaucher's disease, hereditary spherocytosis, etc.) and suggested that accessory spleens represent physiological responses to demand for phagocytic capacity provided by the reticuloendothelial system in the spleen, rather than as passive developmental anomalies. This hypothesis predicted that simulation of the basic defect might yield a laboratory model for the induction and study of accessory spleens in rabbits. Phenylhydrazine was used for this purpose and it was shown that the frequency of accessory spleens in 80 rabbits so treated was 45%. Most of these accessories appeared to arise de novo because pretreatment examination in situ by laparotomy revealed a naturally occurring frequency of about 7.5%. These results supported, and provide a basis for, observations by surgeons that subsequent to an initial splenectomy, during which spleniculi were noted to be absent, recurrent indications for splenectomy would later reveal functional accessory spleens. No evidence was found to relate anemia, per se, or cardiovascular anomalies to the increased frequency of accessory spleens in rabbits. It was suggested that heritable factors limit the upward expression of accessory spleens in “normal” populations, as well as during the course of certain diseases and of phenylhydr

ISSN:0040-3709    

DOI:10.1002/tera.1420130303

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

年代:1976

数据来源: WILEY

摘要:

AbstractSixteen compounds related to ethylenethiourea and to its parent compound, ethylenebisdithiocarbamate, were investigated to determine the structural requirement for teratogenicity. Modifications of the molecular structure of ethylenethiourea involved altered ring size and added heteroatoms and substituents. Only ethylenethiourea and 4‐methylethylenethiourea were teratogenic, indicating that teratogenicity was intimately linked with the imidazolidinethione structur

ISSN:0040-3709    

DOI:10.1002/tera.1420130304

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

年代:1976

数据来源: WILEY

摘要:

AbstractNumbers of mitotic figures present in parasagittal sections of lens capsules of day‐20 fetal rat eyes and comparison of relative lens volume provided a quantitative basis for comparing tissues fixed in neutral buffered formalin and Bouin's and Lillie's fluids. The number of mitotic figures at 1 or 6 h postmortem was significantly higher in Bouin's and Lillie's‐fixed material than in that fixed in formalin. The estimated volume of the tissue fixed in Bouin's was significantly greater than that of lenses in the other 2 fixatives. In addition the overall appearance of the sectioned lens was examined in an effort to evaluate possible artifacts, especially those that might be interpreted as cataracts. Excessive shrinkage and fragmentation of formalin‐fixed lenses was obs

ISSN:0040-3709    

DOI:10.1002/tera.1420130305

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe distribution of mercury was studied in pregnant and fetal rats after administration at days 11, 13, and 19 of pregnancy. Methyl‐203Hg‐chloride was used as a tracer to determine amounts of mercury in brain, kidneys, liver, heart, placenta, and whole fetus. The fetal brain was shown to accumulate 19 times more of the amount in the fetus than did the maternal brain the amount in the pregnant female. In addition, the fetal brain concentration was 3.4 times higher than the maternal brain concentration. Clearance studies showed that the organ concentrations were variable with little change occurring in maternal brain and fetus. These results are consistent with sensitivity to mercury damage being greater in the fetal than the maternal br

ISSN:0040-3709    

DOI:10.1002/tera.1420130306

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

年代:1976

数据来源: WILEY

摘要:

AbstractIn a study of 100 cerebellums from children dying with meningomyelocele, the lobular pattern of the dislocated segment was identified and classified. There was a graded variation in the degree of cerebellar deformity ranging from complete absence of cerebellar tissue in the upper cervical canal to one in which the upper cerebellar lobules were displaced through the foramen magnum. Within this range there were 2 instances in which the cerebellar defect conformed to that found in the Chiari type 1 deformity, consisting of prolapse of tonsillar tissue only. During fetal life the lobular relation in the caudal aspect of the cerebellum undergoes considerable change and it is likely that the type of deformity present in the cervical canal is closely related to the stage of cerebellar development at which the alteration in growth has its inception. The evidence presented argues against the defect being of a primary developmental nature. The terms “Chiari type 1 deformity” and “Arnold‐Chiari malformation” have outlived their usefulness and future descriptions of the cerebellum in children with hindbrain deformities should indicate the shape of the lobules and precise ones involved in the h

ISSN:0040-3709    

DOI:10.1002/tera.1420130307

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

年代:1976

数据来源: WILEY

摘要:

AbstractCoxsackieviruses B1, B3, B4, and B5 injected into TO outbred mice on the 8th day of pregnancy resulted in increased fetal wastage and growth retardation. Coxsackievirus B2 caused increased fetal wastage, whereas Coxsackievirus B6 exhibited no fetal effects. Pregnant animals injected with viruses causing fetal growth impairment ate more food than controls yet did not increase their body weight as much as control animals. Autopsy and pathological findings of advanced destruction of pancreatic exocrine‐tissue and hepatic‐cell vacuolation suggest that the animals were subject to a dietary defect resulting from pancreatic exocrine insufficiency. Fetal growth impairment in mice due to infection with certain Coxsackieviruses of the B group appears to be largely due to a virus‐induced reduction in the state of maternal health. However, since some of these viruses have been shown to pass transplacentally, further studies are necessary to show whether the viruses may also exert a direct effect on fetal ti

ISSN:0040-3709    

DOI:10.1002/tera.1420130308

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

年代:1976

数据来源: WILEY

摘要:

AbstractPregnant Sprague‐Dawley rats were exposed to 50, 100, 200, 800, 1600, or 3200 ppm halothane on days 8, 9, 10, 11, and 12 of pregnancy. This did not result in increased fetal death and resorption rates, growth retardation, or an increased frequency of skeletal anomalies. When rats were exposed to 1600 ppm halothane on days 1–21 of pregnancy fetal growth was retarded but the differences in the number of centers of ossification in the skeletons were not significant. Skeletal anomalies including supplementary ribs, defective or delayed ossification of sternebrae, and missing centers of ossification in the lower parts of the limbs were seen in some fetuses in all groups but the frequency was not treatment related. Our results indicate that in Sprague‐Dawley rats halothane is not teratogenic or otherwise fetotoxic at subanesthetic concentra

ISSN:0040-3709    

DOI:10.1002/tera.1420130309

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

年代:1976

数据来源: WILEY

摘要:

AbstractExamination, including gonadal sexing, of Sprague‐Dawley‐derived rats with acetazolamide‐induced dysmelia did not reveal deformity in significantly more females than males. The attributes considered were frequency of defects, prevalence of bilateral lesions, number of litters in which both sexes were present but only 1 was malformed, and severity of anomalies as assessed by the number of residual digits in malformed paws. Unlike the morphological pattern of the dysmelia, which seems stereotyped among the sexes in mice and rats, sex‐determined variation in its severity is not a constant feature of the limb lesions induced by acetazolamide

ISSN:0040-3709    

DOI:10.1002/tera.1420130310

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

年代:1976

数据来源: WILEY

摘要:

AbstractFetal survival, malformation rate, and fetal and placental weights were examined near term in control rabbits, rabbits treated on day 6 with 5 mg of medroxyprogesterone acetate (MPA), a long acting progestin, and rabbits treated with 5 mg of MPA on day 6 and ovariectomized on day 7. MPA alone had no apparent effect on fetal or placental development but MPA plus ovariectomy increased fetal weight by 19% and placental weight by 60%. Fetal and placental development were examined near term in rats given similar treatments. One milligram of MPA administered alone on day 7 had no apparent effect. However, in rats given 1 mg of MPA on day 6 and ovariectomized on day 7 no fetuses survived. In rats given 1 mg of MPA on day 11 and ovariectomized on day 12 only 4.7% of the fetuses survived and all were pressure malformed. In rats given 1 mg of MPA on day 11, ovariectomized on day 12, and supplemented daily with 0.5 μg of estradiol benzoate thereafter, 40% of the fetuses survived and none was malformed, but fetal weights were 22% and placental weights 15% below those of the controls. The underlying problem in the ovariectomized rats supplemented with progestins alone appeared to be failure of myometrial growth. These results highlight the species differences in steroid hormone requirements for fetal, placental, and myometrial development during pregnancy

ISSN:0040-3709    

DOI:10.1002/tera.1420130311

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

年代:1976

数据来源: WILEY