Mammalian chimaeras / Anne McLaren.

  • McLaren, Anne.
Date:
[1976]
Catalogue details

Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: Mammalian chimaeras / Anne McLaren. Source: Wellcome Collection.

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    Progeny of single-sex chimaeras 47 Table 7. Segregation of progeny in 12 litters sired by a male chimaera paired with 6 females {a-f) of the recessive stock From McLaren (1975o). in which the proportions of the two types of young do not vary significantly between litters (д:^{28) = 27.0; ^-^(26) = 29.0); on the other hand, McLaren (1975«) found that the proportions of the two types of young sired by male chimaeras involving a multiple recessive strain shifted very significantly from one litter to another throughout reproductive life (e.g. Table 7). The variations did not seem to follow any regular trend; they were not related to the age of the male, nor to the age or identity of the female bearing the litter. Perhaps the area of a spermatogenic tubule that is colonized by the descendants of a single germ cell or patch of germ cells can be extensive enough to occupy most of an ejaculate; perhaps indeed this area comprises an entire tubule, with the tubules being emptied one at a time into the common collecting duct. In chimaeras involving the multiple recessive strain, patches of the two types of cell may be relatively large. The absence of any heterogeneity in the CBA- Тб'Н^СВА-р progenies may reflect the close genetic relationship between the components in this strain combination. The lack of an age effect is in contrast to the situation described by Mintz (1968, 1969úr). When C57BL<-^C3H/He chimaeras were mated to C57BL partners, the proportion of C57BL young decreased sharply with time when male chimaeras were used. When the chimaeric partner was the female, although C3H germ cells still appeared to predominate, there was said to be no change with time. The effect in males was interpreted as indicating con¬ tinuous selection against C57BL germ cells in the chimaeric testis; in the female the germ cell population is established prenatally, and no further cell