Fetus, 18 Weeks, Lennart Nilsson, 1965

When LIFE published Lennart Nilsson’s photo essay “Drama of Life Before Birth” in 1965, the issue was so popular that it sold out within days. And for good reason. Nilsson’s images publicly revealed for the first time what a developing fetus looks like, and in the process raised pointed new questions about when life begins. In the accompanying story,

LIFE explained that all but one of the fetuses pictured were photographed outside the womb and had been removed—or aborted—“for a variety of medical reasons.” Nilsson had struck a deal with a hospital in Stockholm, whose doctors called him whenever a fetus was available to photograph. There, in a dedicated room with lights and lenses specially designed for the project, Nilsson arranged the fetuses so they appeared to be floating as if in the womb. In the years since Nilsson’s essay was published, the images have been widely appropriated without his permission. Antiabortion activists in particular have used them to advance their cause. (Nilsson has never taken a public stand on abortion.) Still, decades after they first appeared, Nilsson’s images endure for their unprecedentedly clear, detailed view of human life at its earliest stages.