XIV.—The Genetical and Mechanical Properties of Sex Chromosomes. III. Man

Abstract

In the male chromosome complement of man, Painter (1923) found that one chromosome pair is heteromorphic and forms an asymmetrical or unequal bivalent during meiotic metaphase, and consequently two kinds of gametes are produced. One member of this heteromorphic pair is about three times longer than the other and is designated the X, the other is described as the Y chromosome. Though the sex chromosomes of man were carefully studied and identified with certainty throughout the nuclear cycle of mitosis and meiosis by several investigators (cf. Shiwago and Andres, 1932), no further attempt was made to correlate the peculiar pairing properties of the heteromorphic chromosomes with their qualitative and structural differentiation.