Early morphological signs of embryonic genome expression in human preimplantation development as revealed by quantitative electron microscopy.
A quantitative electron microscopic analysis of human preimplantation embryos in conjunction with [3H]uridine labeling and light microscopic autoradiography revealed significant differences in the fractional volume of some cell organelles between the blastomeres of eight-cell embryos with fully activated extranucleolar and nucleolar transcription and those showing low extranucleolar and no nucleolar RNA synthesis, a pattern typical of four-cell human embryos. The latter type of blastomeres in eight-cell embryos did not show any significant quantitative cytological difference when compared to blastomeres of four-cell embryos. The phenotypical changes accompanying the overall enhancement of the embryonic transcriptional activity (increase in tubules/vesicles ratio and lysosomes, decrease in Golgi apparatus) were due to repartition of intracellular membranes amongst different types of organelles rather than to a noticeable change in the existing equilibrium between total membrane production and degradation.
Tesarík
J
J
Station Centrale de Physiologie Animale, INRA, Jouy-en-Josas, France.
Kopecný
V
V
Plachot
M
M
Mandelbaum
J
J
D001757:Blastomeres / Q000378:metabolism / Q000648:ultrastructure*; D002466:Cell Nucleolus / Q000378:metabolism / Q000648:ultrastructure; D003593:Cytoplasm / Q000648:ultrastructure; D004721:Endoplasmic Reticulum / Q000648:ultrastructure; D005786:Gene Expression Regulation; D006056:Golgi Apparatus / Q000648:ultrastructure; D006801:Humans; D007425:Intracellular Membranes / Q000648:ultrastructure; D008247:Lysosomes / Q000648:ultrastructure; D008854:Microscopy, Electron; D012313:RNA / Q000096:biosynthesis; D014158:Transcription, Genetic
D012313:RNA