Practice question

Wilhelm Roux in 1888 destroyed one blastomere of a two-cell frog embryo using a hot needle, leaving damaged cytoplasm attached, and observed formation of half embryos lacking structures normally contributed by ablated cell. Though artifact partly due to retained dead cell interfering with regulation, result was interpreted as evidence for mosaic autonomous development where fate determinants are divided progressively during cleavage like mosaic tiles. Later refined by Spemann using hair ligature separating healthy blastomeres, which showed regulation, but Roux experiment remains historical prototype demonstrating concept of autonomous specification and inspiring subsequent regulative versus mosaic debate.