Separation of trophoblastic and vascular cell lineages and vascular maturation in early human placental development.
The trophoblast and vascular cell lineages have been studied by immunohistochemistry at 6 and 12-14 weeks of pregnancy. Perivillous and extravillous cytotrophoblasts were specifically stained by anti-cytokeratin 7 whereas endothelial cells were labelled by anti-CD34 at these two stages of pregnancy. Perivillous and extravillous cytotrophoblasts together with erythroblasts showed mitotic figures and anti-Ki67 positive nuclei at the 6th week. In the perivillous cytotrophoblast, the number of Ki67 positive nuclei decreased by 12-14 weeks and the staining was limited to the proximal extravillous trophoblast of cell islands. Some endothelial and perivascular cells were labelled with anti-Ki67 at 12-14 weeks. Erythroblasts did not stain at all at this stage. Endothelial cells bound lectin UEA1 and vessels exhibited a fluorescent signal after anti-myosin staining at 12-14 weeks. These data showed that the cytotrophoblast and endothelial cell lineages are not related from 6 to 12-14 weeks of pregnancy. Because mitotic figures or anti-Ki67 staining were not observed in endothelium or perivascular cells at the 6th week, it seems likely that the endothelial cells committed to vasculogenesis derived from stromal cells. By 12-14 weeks, endothelial cells had nearly achieved their maturation by acquiring 1-fucosyl-binding sites revealed by UEA1-lectin binding and insuring their own renewal by mitosis. The maturation of perivascular cells at 12-14 weeks was shown by the anti-sm-myosin staining. We conclude that placental vasculogenesis involves mesenchymal cells rather than trophoblast. The differenciation of vessels organizing from random plexi to a vascular arborescence may involve paracrine regulatory loops with the trophoblast.
Challier
J C
JC
Physiopathologie de l'Implantation et du Développement, Upres 2396, Faculté de Médecine St Antoine, Paris 75012, France. jcch@ccr.jussieu.fr
Landi
M
M
Galtier
M
M
Bintein
T
T
Cortez
A
A
Rabreau
M
M
D001808:Blood Vessels / Q000166:cytology / Q000196:embryology*; D002454:Cell Differentiation; D019070:Cell Lineage; D002467:Cell Nucleus / Q000737:chemistry; D002824:Chorionic Villi / Q000648:ultrastructure; D004730:Endothelium, Vascular / Q000166:cytology* / Q000196:embryology* / Q000502:physiology; D004900:Erythroblasts / Q000502:physiology; D005260:Female; D006801:Humans; D019394:Ki-67 Antigen / Q000032:analysis / Q000378:metabolism; D008938:Mitosis / Q000502:physiology; D010920:Placenta / Q000166:cytology; D010929:Placentation / Q000502:physiology*; D011247:Pregnancy; D014327:Trophoblasts / Q000166:cytology* / Q000502:physiology
D019394:Ki-67 Antigen