Complex sentence: He and his students focused on direct observation of cell behavior using light microscopy and discovered many of the fundamental aspects of fertilization, development, and morphogenesis (e.g., Dan and Okazaki, 1956).
Split into simpler sentences: He and his students focused on direct observation of cell behavior using light microscopy. In this way they discovered many fundamental cell biological aspects of fertilization, development, and morphogenesis (e.g., Dan and Okazaki, 1956).