95 gestion that viruses, from the type which appears to be of molecular proportions to those which are essentially microorganisms in the bacterial sense-have one (at least) distinguishing characteristic in common,-parasitism. From this he deduces: "We would suppose that the larger viruses were organisms which had lost the power to synthesise some factor or factors essential for their growth and...

Novel approaches to bio-imaging and automated computational image processing allow the design of truly quantitative studies in developmental biology. Cell behavior, cell fate decisions, cell interactions during tissue morphogenesis, and gene expression dynamics can be analyzed in vivo for entire complex organisms and throughout embryonic development. We review state-of-the-art technology for li...

Retinoids are synthetic and natural analogues of vitamin A that have various effects on cellular differentiation, cellular proliferation, immune system, and embryonic development. The present study reviews the history of systemic retinoids in medicine, the structure of syn