[Quantitative aspects of the colonization of the gonads by germ cells in the quail embryo (Coturnix coturnix japonical)].

A quantitative analysis made on quail embryos coming from 13 isolated parent-couples reveals some significative variations of a genetic origin, between some of the offspring studied: the differences observed concern both the quantitative importance of the colonization of gonads by germ cells and the asymmetrical distribution of PGGs (primordial germ cells) between the two genital ridges. The chronological study of the colonization in the quail shows, as in both the duck and the chick, two periods of rapid and regular increase of the number of gonadic PGC, at stages from 13 to 18 and from 24 to 30 of Hamburger & Hamilton. The distribution of germ cells between the two genital ridges is, at the beginning of the colonization, not very asymmetrical. Between stages 18 and 24 the asymmetry increases and remains stable so that the mean value of D% (percentage of the number of PGC contained in the right gonad) from that moment on is equal to 29-34%. This value is specific for the quail embryo.