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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    Cell markers 15 The injection technique can be used in situations for which aggregation methods are inappropriate, e.g. for species such as the rabbit (Moustafa, 1974) where removal of the zona pellucida precludes subsequent development, or for making between-species chimaeras (Gardner & Johnson, 1973), where a double contribution to the outer trophoblast layer might interfere with normal implantation in the host uterus. Cell markers The ideal cell marker to distinguish one chimaera component from the other would be cell-localized, cell-autonomous, stable, distributed universally among both the internal and the external tissues of the body, and easy to detect, both grossly and in histological sections, without elaborate processing. It would have several genetically determined variants, characterizing different strains. No such marker exists. Early development For the analysis of blastomere distribution during early development, use has been made of genetic differences in granularity of the cytoplasm, and of the abnormal appearance of homozygous lethal embryos (Mintz, 1964û). Tritiated-thymidine labelling of one component has also been used as a marker (Mintz, 1964^7; Garner & McLaren, 1974), but no attempt has yet been made to apply techniques of vital staining, as used for example by Daniel & Olsen (1966) on rabbit embryos. Antigenic markers Antigenic variation comes closest to the ideal, and has been exploited in a number of different ways. Histocompatibility antigens potentially satisfy all the requirements listed above, since they are cell-localized, cell-autono¬ mous, present in all tissues, and possessed of a virtually infinite amount of genetic variation. The only problems arise in their detection. Red cell antigens are easy to detect by haemagglutination tests, so can be used to register and quantitate erytjirocyte chimaerism in strain combinations differing at appro¬ priate histocompatibility loci (Mintz & Palm, 1965f, 1969; Wegmann & Gilman, 1970). Lymphocytes can be typed, using theta antigens (Bona, Tuffrey & Barnes, 1974). Skin grafting onto recipients of the component strains has been used in an attempt to study chimaerism in hair follicles and melanocytes (Mintz & Silvers, 1970), but the interpretation of partial graft breakdown is difficult. Immunofluorescent methods for antigen detection of tissue sections offer the most promising approach to localization at the cellular level, but unfortunately the techniques are complicated and often