[Cytological research on localizing argentophilic proteins in one-cell mouse embryos]

Localization of argentophilic proteins on mouse one-cell embryos has been studied under light and electron microscope using the silver staining that reveals transcriptionally active nucleolus-organizing chromosome regions (NORs). Although argentophilic proteins are observed in NORs of metaphase chromosomes only after the second cleavage division, they can be detected in nuclear apparatus of one-cell embryos, that is at the stage when ribosomal genes are not yet transcribed. Argentophilic proteins are visualized on the surface of decondensing chromatin of the spermatozoon head and on maternal telophase chromosomes immediately after the fertilization. They migrate into pronuclei and are accumulated in pronucleoli. During mitosis argentophilic proteins bind to chromosomes and move to cytoplasm. The importance of argentophilic proteins at the initial stages of mammalian embryogenesis is discussed.