Mouse primitive streak forms in situ by initiation of epithelial to mesenchymal transition without migration of a cell population.

Background: During gastrulation, an embryo acquires the three primordial germ layers that will give rise to all of the tissues in the body. In amniote embryos, this process occurs via an epithelial to mesenchymal transition (EMT) of epiblast cells at the primitive streak. Although the primitive streak is vital to development, many aspects of how it forms and functions remain poorly understood.

Leucine and arginine regulate trophoblast motility through mTOR-dependent and independent pathways in the preimplantation mouse embryo.

Uterine implantation is a critical element of mammalian reproduction and is a tightly and highly coordinated event. An intricate and reciprocal uterine-embryo dialog exists to synchronize uterine receptivity with the concomitant activation of the blastocyst, maximizing implantation success. While a number of pathways involved in regulating uterine receptivity have been identified in the mouse, less is understood about blastocyst activation, the process by which the trophectoderm (TE) receives extrinsic cues that initiate new characteristics essential for implantation.

PTK7 is essential for polarized cell motility and convergent extension during mouse gastrulation.

Despite being implicated as a mechanism driving gastrulation and body axis elongation in mouse embryos, the cellular mechanisms underlying mammalian convergent extension (CE) are unknown. Here we show, with high-resolution time-lapse imaging of living mouse embryos, that mesodermal CE occurs by mediolateral cell intercalation, driven by mediolaterally polarized cell behavior. The initial events in the onset of CE are mediolateral elongation, alignment and orientation of mesoderm cells as they exit the primitive streak.

Limb regeneration in higher vertebrates: developing a roadmap.

We review what is known about amphibian limb regeneration from the prospective of developing strategies for the induction of regeneration in adult mammals. Prominent in urodele amphibian limb regeneration is the formation of a blastema of undifferentiated cells that goes on to reform the limb. The blastema shares many properties with the developing limb bud; thus, the outgrowth phase of regeneration can be thought of as cells going through development again, i.

Mouse pigpen encodes a nuclear protein whose expression is developmentally regulated during craniofacial morphogenesis.

Pigpen, a nuclear protein with RNA-binding motifs and a putative transcriptional activation domain (TAD), is expressed at high levels in proliferating endothelial cells and expression is down-regulated when cells adopt a quiescent or differentiated phenotype. We cloned the mouse homolog of pigpen and investigated the regulation of its expression during embryogenesis. In situ hybridization demonstrated that a broad pattern of pigpen expression became restricted during tooth formation in the mandible.