Analysis of the mitotic index of chicken primordial germ cells before and after settling in the germinal ridge

Abstract

The mitotic index of chicken primordial germ cells was determined by analysing the nuclear DNA content and the number of M phase and S phase primordial germ cells at stage 14-15 (before settling in the germinal ridge) and at stage 17-18 (after settling in the germinal ridge) using an interactive laser cytometer. When nuclear DNA content was presented graphically, two peaks were revealed at each of the two stages being studied. The value of the second peak was approximately twice that of the first peak. Primordial germ cells, having two nuclei in one cell, were recognized at each stage and were considered to be at M phase in cell division. The amount of nuclear DNA in both S and M phases was correlated with that between the first and the second peaks and that in the second peak, respectively. The number of M phase and S phase primordial germ cells significantly increased after they had settled in the germinal ridge. These results suggest that chicken primordial germ cells start to proliferate actively as soon as they reach the gonadal ridge.