Ourselves Unborn

Abstract

ALTHOUGH the embryonic development of man is one of the most copiously described of natural processes, until a few years ago there were several gaps in the story so far as it was known. The gaps, moreover, occurred at the most crucial stage, right at the beginning. Until a decade or so ago, the earliest known human embryos presented the picture of a minute vesicle, covered in villi and buried within the thickness of the uterine wall, the body of the vesicle consisting of a spongy tissue containing two small cavities between which the embryo reposed in the form of a flat plate. It was hard to draw any convincing analogies between this structure and that of the presumably comparable stages of other mammalian embryos. The early human embryo seemed aberrant in almost all its features; few other mammalian embryos bury themselves in the uterine wall, and no others were known with a similar development of spongy tissue, which might be considered either endodermal or mesodermal.

Ourselves Unborn

An Embryologist's Essay on Man. By George W. Corner. (The Terry Lectures.) Pp. xiv + 188 + 8 plates. (New Haven, Conn.: Yale University Press; London: Oxford University Press, 1944.) 20s. net.