Thy-1 differentiation protein and monocyte-derived cells during regeneration and aging of human placental villi.
OBJECTIVE
The classification of placental villi was reviewed, and regeneration of villous trees in mature human placentae was examined.


METHODS
Expression of Thy-1 by placental fibroblasts and pericytes, and markers of endothelial cells and monocyte-derived cells were studied by immunohistochemistry and image analysis.


RESULTS
Villous regeneration consists of: (i) dedifferentiation of mature ramuli into young stem villi producing mesenchymal villi; (ii) differentiation of mesenchymal villi into immature intermediate villi; and (iii) differentiation of immature intermediate villi into transitory intermediate villi, branching into the precursors of mature intermediate and terminal villi. These processes are associated with dedifferentiation and redifferentiation of placental monocyte-derived cells. Significant changes of Thy-1 expression by fibroblasts and pericytes accompany aging and degeneration, as well as regeneration of placental villi.


CONCLUSIONS
Villous aging and degeneration in normal mature human placenta is compensated by regeneration of villous trees. Lack of villous regeneration may cause chronic fetal distress, due to the increasing demands of the growing fetus on the remaining terminal villi.
Bukovsky
A
A
Department of Obstetrics and Gynecology, The University of Tennessee Graduate School of Medicine, Knoxville 37920, USA.
Caudle
M R
MR
Keenan
J A
JA
Wimalasena
J
J
McKenzie
P P
PP
D016922:Cellular Senescence / Q000276:immunology*; D002824:Chorionic Villi / Q000254:growth & development* / Q000378:metabolism / Q000502:physiology*; D004727:Endothelium / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D009000:Monocytes / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D012038:Regeneration / Q000276:immunology*; D018800:Thy-1 Antigens / Q000096:biosynthesis*
D018800:Thy-1 Antigens