Trophoblast phagocytic program: roles in different placental systems
Review | Published: 10 September 2009
Estela Bevilacqua*,1, Mara-Sandra Hoshida1, Andrea Amarante-Paffaro2, Andrea Albieri-Borges3 and Sara Zago-Gomes1
1University of São Paulo, SP, 2Federal University of Alfenas, MG and 3State University of Rio de Janeiro, RJ, Brazil
Although not belonging to the class of professional phagocytes, in many species trophoblast cells exhibit intense phagocytic activity. The complete range of physiological functions of trophoblast phagocytosis has not yet been fully characterized. Close association between the trophoblast and nutrition was determined many years ago. Hubrecht (1889) when proposing for the first time the name trophoblast to the external layer of the blastocyst, directly established the nutritive significance of this embryonic layer. Indeed, histotrophic phagocytosis, i.e. the internalization of maternal cells and secreted materials, is considered an important function of the trophoblast before the completion of the placenta. Recently, however, unexpected characteristics of the trophoblast have significantly enhanced our understanding of this process. Roles in acquisition of space for embryo development, in tissue remodeling during implantation and placentation and in defense mechanisms are highlighting how this cellular activity may be relevant for the maternal-fetal relationship beyond its nutritional function.