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  • 1980-1984  (2)
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  • 1
    ISSN: 1573-6857
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A preliminary investigation of reproductive capacity in XO mice showed that they produced smaller litters than normal litter mates. More time elapsed between successive litters when kept in the presence of a male except during pregnancy and weaning. This lower level of reproduction is manifest during the whole reproductive period. Also reproductive capacity in XO mice reaches its maximum and minimum (end of reproductive period) earlier than in normals. Further study also demonstrated an underdevelopment of the ovaries-the whole ovary, as well as the numbers of maturing and mature follicles, are smaller in XO mice than in controls. Since these differences can be corrected by unilateral ovariectomy, they appear to be under control of extra-ovarial factors, e.g. of gonadotropic hormone(s). The data also suggest depression of activity in the oestrogen-producing system, and in general that the lower reproductivity of XO mice may be attributed to a diminished secretion of gonadotropic hormones together with a smaller number of primordial germ cells in XO mice. The segregation from XO parents seems to favor transmission of X-gametes in young mothers, with however the preference for X tending to decrease with parental age. Since the data tend to rule out postzygotic selection effects, the excess of X-bearing gametes may relate to meiotic drive.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Genetica 55 (1981), S. 179-185 
    ISSN: 1573-6857
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The growth rate of XO mice during the first five weeks of life was shown to be significantly lower (ca. 15%) than the growth rate of normal XX mice. A marker gene Tabby was introduced in order to recognize hemizygous XO females. The presence or absence of this gene had a significant influence on growth rates. XO females could only be compared to XX females in an indirect way. The differences found could not be attributed to maternal influence or to the influence of litter size. Body temperature and thyroid activity were found to be lower in XO mice than in normal females. It is suggested that the lower growth rate characteristic of the XO mice is a consequence of hypothyroidism and a lower basal metabolic rate. The results show that phenotypically XO mice are not entirely normal and at least two normal X's are necessary for complete development.
    Type of Medium: Electronic Resource
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