Systematic localization of Oct-3/4 to the gastrulating mouse conceptus suggests manifold roles in mammalian development.

Oct-3/4 was localized to the mouse conceptus between the onset of gastrulation and 16-somite pairs (-s; approximately 6.5-9.25 days postcoitum, dpc). Results revealed Oct-3/4 in a continuum of morphologically distinct epiblast-derived embryonic and extraembryonic tissues. In the allantois, distal-to-proximal diminution in the Oct-3/4 domain over time and co-localization with Flk-1 in angioblasts accorded with a role in vascular differentiation and the presence of a stem cell reservoir. In addition, visceral endoderm exhibited a dynamic salt-and-pepper distribution, which, combined with previous results of fate mapping and gene expression, suggested that Oct-3/4 is involved in the genesis of definitive endoderm. By 8-s, Oct-3/4 was globally down regulated in all but putative primordial germ cells (PGCs) and some allantoic cell clusters. Taken together, Oct-3/4's expression profile suggests unexpected and potentially far more versatile roles in development than have been previously appreciated.     

Collagen type IV and Perlecan exhibit dynamic localization in the Allantoic Core Domain,a putative stem cell niche in the murine allantois

A body of evidence suggests that the murine allantois contains a stem cell niche, the Allantoic Core Domain (ACD), that may contribute to a variety of allantoic and embryonic cell types. Given that extracellular matrix (ECM) regulates cell fate and function in niches, the allantois was systematically examined for Collagen type IV (ColIV) and Perlecan, both of which are associated with stem cell proliferation and differentiation. Not only was localization of ColIV and Perlecan more widespread during gastrulation than previously reported, but protein localization profiles were particularly robust and dynamic within the allantois and associated visceral endoderm as the ACD formed and matured. We propose that these data provide further evidence that the ACD is a stem cell niche whose activity is synchronized with associated visceral endoderm, possibly via ECM proteins. Developmental Dynamics 238:3193–3204, 2009. © 2009 Wiley‐Liss, Inc.