The Downs Laboratory
Faculty > Karen M. Downs
Karen M. Downs
Professor, Cell and Regenerative Biology
kdowns@wisc.edu
Organ System/Disease Focus
Umbilical cord; vasculogenesis; placentation
Aligned Research Focus
Putative stem cell reservoir in the mouse allantois and its role in building the posterior region of the conceptus.
Research Description
Emerging from the posterior end of the mouse embryo, the allantois will become the umbilical component of the chorio-allantoic placenta. The allantois is generated by mechanisms involving the primitive streak and possibly, visceral endoderm.
We recently reported the presence of several new architectural features in the mouse allantois. The Brachyury-defined Allantoic Core Domain (ACD), or ACD may be a stem cell reservoir created by interactions between the primitive streak and overlying visceral endoderm. From it, multiple posterior cell types are deployed. In particular, we have recently provided evidence that the STELLA-positive cell population, thought to identify primordial germ cells (PGCs), may not be restricted to the PGCs, but rather, contributes to a broader array of posterior cell types.
We have also identified distinct components of the outer surface of the allantois, called “mesothelium”. In particular, the Ventral Cuboidal Mesothelium (VCM) contains abundant Hedgehog, and overlies the ACD and site of formation of a unique hemogenic vessel, provisionally called the “vessel of confluence”, or VOC. The VOC appears to be a fixed site relative to the allantois-derived umbilical cored, where the arterial systems unite and are channeled to the chorionic component of the placenta. It also seems to be the site from which the omphalomeseneteric artery is formed, and other vessels are remodeled.
Selected References
Mikedis, M. M. and Downs, K. M. (2012). STELLA-positive subregions of the primitive streak contribute to posterior tissues of the mouse gastrula. Dev. Biol. 363, 201-218.
Downs, K. M. (, Inman, K. E., Jin, D. X., and Enders, A. C. (2009). The Allantoic Core Domain (ACD): New insights into development of the murine allantois and its relation to the primitive streak. Dev. Dyn. 238, 532-553.
Downs, K. M. ( (2008). Systematic localization of Oct-3/4 (Pou5f1) to the gastrulating mouse conceptus suggests manifold roles for Oct-3/4 in mammalian development. Dev. Dyn., 237, 464-474.
Ziegler, B. M., Sugiyama, D., Chen, M., Guo, Y., Downs, K. M. (, and Speck, N. A. (strong>(co-corresponding authors() (2006). The allantois and chorion, isolated before circulation or chorio-allantoic fusion, have hematopoietic potential. Development 133, 4183-4192 (Featured in “In This Issue”).
Uy, G.D., Downs, K.M. (, and Gardner, R. L. (2002). Inhibition of trophoblast stem cell potential in chorionic ectoderm coincides with occlusion of the ectoplacental cavity in the mouse. Development, 129, 3913-3924. .