late heart stage

基本解释

There were only two layers of nucellus which had abundant cytoplasm and reserved substance, and were consumed at the stage of late heart-shaped embryo.
珠心细胞只有两层，细胞核大，胞质丰富，内含贮藏物质，至心形胚期逐渐解体。

But this second, more pernicious, late stage failure issue has at its heart the same issue you identify: hubris.
FORBES: Are We The Problem? The Role Of Poor Decision-Making In Stifling Drug Development
But late-stage trials presented here at the annual meeting of the American Heart Association were promising enough that Acorn plans to file for marketing approval with the U.S. Food and Drug Administration by Dec. 10, with hopes of a decision in 2005.
FORBES: Heart Failing? Put A Sock On It