Cytological, immunohistological and immunocytological methods will be used to investigate the role of different trophoblast populations during implantation in the macaque, and to compare these observations with those in two species, the rat and horse, exhibiting different patterns of epithelial and stromal invasion. The role of fetal-maternal cell fusion in expansion of trophoblast along the plane of the epithelium will be studied in the macaque using cytological and cell marker techniques. The extent of linkage between cytotrophoblast cells and cytotrophoblast cells and syncytial trophoblast will be studied using antibodies to junctional complex constituent proteins in this species. DNA synthesis in trophoblast populations will be examined using 3H thymidine incorporation in vitro in macaque implantation sites. The role of selected cell adhesion molecules in interaction of trophoblast and uterine tissues will be followed using antibody methods during implantation and early placentation in the macaque and rat. As a means of characterizing different trophoblast populations and providing functional implications the distribution of lysosomal and nonlysosomal lytic enzymes will be mapped in macaque trophoblastic plate to anchoring villous stages. Surface modifications and differentiation of equine girdle cells will be examined as they relate to migration of these cells into the endometrium. Adhesion molecules also will be studied in relationship to segregating cell populations in the uterus and trophoblast of the rat during implantation and early placentation. Adhesion molecules between trophoblast cells and endothelial cells will be localized to establish their role in formation of vascular patterns in the macaque and rat, and the manner in which equine trophoblast cells invade lymphatic vessels but not capillaries will be examined. Finally, embryos obtained during the macaque studies will be used to examine the manner of formation of the secondary yolk sac and the contribution of the prochordal plate and notochordal process to the establishment of definitive intraembryonic endoderm. It is believed that these studies can make a substantial contribution to our understanding of the way in which trophoblast cells can interact with the endometrium during the crucial implantation stages preceding placentation.

National Institute of Health (NIH)
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Research Project (R01)
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Human Embryology and Development Subcommittee 1 (HED)
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University of California Davis
Schools of Medicine
United States
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Enders, A C; Blankenship, T N (2012) Interstitial trophoblast cells: an enigmatic and variable component of the developing macaque placenta. Placenta 33:672-6
Enders, A C (2007) Implantation in the macaque: expansion of the implantation site during the first week of implantation. Placenta 28:794-802
Julian, JoAnne; Enders, Allen C; Fazleabas, Asgerally T et al. (2005) Compartmental distinctions in uterine Muc-1 expression during early pregnancy in cynomolgous macaque (Macaca fascicularis) and baboon (Papio anubis). Hum Reprod 20:1493-503
Enders, A C (2002) Formation of monozygotic twins: when does it occur? Placenta 23:236-8
Enders, A C (2002) Implantation in the nine-banded armadillo: how does a single blastocyst form four embryos? Placenta 23:71-85
Enders, A C; Blankenship, T N; Fazleabas, A T et al. (2001) Structure of anchoring villi and the trophoblastic shell in the human, baboon and macaque placenta. Placenta 22:284-303
Enders, A C (2000) Trophoblast-uterine interactions in the first days of implantation: models for the study of implantation events in the human. Semin Reprod Med 18:255-63
Enders, A C; Liu, I K (2000) A unique exocelom-like space during early pregnancy in the horse. Placenta 21:575-83
Enders, A C; Lopata, A (1999) Implantation in the marmoset monkey: expansion of the early implantation site. Anat Rec 256:279-99
Lantz, K C; Enders, A C; Liu, I K (1998) Possible significance of cells within intraluminal collagen masses in equine oviducts. Anat Rec 252:568-79

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