Planar cell movements and oriented cell division during early primitive streak formation in the mammalian embryo.

Formation of the mammalian primitive streak appears to rely on cell proliferation to a minor extent only, but compensating cell movements have not yet been directly observed. This study analyses individual cell migration and proliferation simultaneously, using multiphoton and differential interference contrast time-lapse microscopy of late pregastrulation rabbit blastocysts. Epiblast cells in the posterior gastrula extension area accumulated medially and displayed complex planar movements including U-turns and a novel type of processional cell movement.

Tracing and ablation of single cells in the mammalian blastocyst using fluorescent DNA staining and multi-photon laser microscopy.

Comparing the vital DNA dyes Hoechst33342 and DAPI in their ability to visualise cell nuclei of the late rabbit blastocyst, both dyes were found to be equally suited despite differences in staining intensity in embryonic versus extraembryonic tissues and in nuclear versus cytoplasmic domains at the subcellular level: Both dyes stain all nuclei of a given cell layer (e.g. epiblast or hypoblast) evenly and provide satisfactory fluorescence contrast throughout the blastocyst, while not interfering with normal development up to 10 h in vitro.