MAGNETIC-RESONANCE MICROSCOPY OF EMBRYONIC-CELL LINEAGES AND MOVEMENTS

Key events in vertebrate embryogenesis are difficult to observe in man y species. High-resolution magnetic resonance imaging was used to foll ow cell movements and lineages in developing frog embryos. A single ce ll was injected at the 16-cell stage with a contrast agent, based on t he gadolinium chelate gadolinium-diethylenetriamine pentaacetic acid-d extran. The labeled progeny cells could be followed uniquely in three- dimensional magnetic resonance images, acquired from the embryo over s everal days. The results show that external ectodermal and internal me sodermal tissues extend at different rates during amphibian gastrulati on and neurulation.