Morphogenesis of the chorio-allantoic placenta involves growth and differentiation of allantoic mesoderm, chorionic ectoderm, and the ectoplacental cone as well as union between these initially well separated tissues. The allantois will become the umbilical cord whilst the chorion, together with the ectoplacental cone in the mouse, will become the mature chorionic disk. Current projects are designed to discover the genetic pathways, environmental cues, and cell-cell and molecular interactions that orchestrate differentiation of allantoic mesoderm into the umbilical vasculature, as well as the major events that regulate union between the allantois, chorion and ectoplacental cone. Further, we have developed a method of allantoic explantation to discover the mechanism of early blood vessel formation and formation of the primordial blood plasma. Specific questions are How does allantoic mesoderm differentiate into endothelial, chorio-adhesive, mesenchymal and smooth muscle lineages?, How is distal-to-proximal polarity of differentiation established in the allantois?, What is the role of the primitive streak in differentiation of allantoic mesoderm?, What are the developmental mechanisms of chorio-allantoic union, and formation of the chorionic disk? Methods of transplantation, whole embryo culture, explants, genetics, molecular biology and gene discovery by microarray analysis are being used in all aspects of this research program.


Recent Publications

Downs, K. M. and Gardner, R. L. (1995). An investigation into early placental ontogeny: allantoic attachment to the chorion is selective and developmentally-regulated. Development 121, 407-416.

Downs, K. M. and Harmann, C. (1997). Developmental potency of the murine allantois. Development 124, 2769-2780.

Downs, K. M., Gifford, S., Blahnik, M. and Gardner, R. L. (1998). Vascularization in the murine allantois occurs by vasculogenesis without accompanying erythropoiesis. Development 125, 4507-4520.

Downs, K. M., Temkin, R., Gifford, S. and McHugh, J. (2001). Study of the murine allantois by allantoic explants. Dev. Biol. 233, 347-364.

Downs, K. M. (2002). Early placentation in the mouse. Placenta, in press.