Cell differentiation in the preimplantation human embryo.
This brief paper analyses current knowledge on gene expression in individual blastomeres of preimplantation mammalian embryos. Initially, current knowledge on axes and cleavage planes in mammalian eggs and embryo blastomeres is described, together with gene and system homologies with flies and nematodes, and their influence on differentiation. Stress is placed on the need to study individual blastomeres, and even specific components within blastomeres. Examples of published work concentrate on the possible allocation of a single founder blastomere for trophectoderm, which contains large amounts of maternal leptin, STAT3 and other proteins positioned at the animal pole. The recent discovery that single human blastomeres in cleaving embryos contain high levels of HCGbeta mRNA and LHbeta mRNA suggests these are also trophectoderm foundation cells. It is now essential to discover if the maternal proteins leptin/STAT3 and maternal/embryonic HCGbeta transcripts locate to the same blastomere. Problems in jointly identifying maternal proteins and embryonic and maternal transcripts for specific proteins within one cell, and the nature of early cell allocation in mouse and human embryo, are discussed.
Hansis
Christoph
C
Program for In-Vitro Fertilization, Reproductive Surgery and Infertility, New York University School of Medicine, 660 First Ave, 5th Floor, New York, NY 10016, USA. ChrHansis@aol.com
Edwards
Robert G
RG
D000818:Animals; D001755:Blastocyst / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure*; D002454:Cell Differentiation; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D047108:Embryonic Development; D005314:Embryonic and Fetal Development; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D020738:Leptin / Q000378:metabolism; D007986:Luteinizing Hormone / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism; D050796:STAT3 Transcription Factor; D013997:Time Factors; D015534:Trans-Activators / Q000378:metabolism
D018997:Chorionic Gonadotropin, beta Subunit, Human; D004268:DNA-Binding Proteins; D020738:Leptin; D012333:RNA, Messenger; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; C494087:Stat3 protein, mouse; D015534:Trans-Activators; D007986:Luteinizing Hormone