Genetic Factors Affect the Number of Circulating Primordial Germ Cells in Early Chick Embryos.

Abstract

Avian primordial germ cells (PGCs) arise from the epiblast and circulate temporarily via the blood vascular system in their migration route to the gonadal anlage. There are egg-to-egg variations in the number of circulating PGCs (cPGCs) at the same developmental stage, which are reportedly due to the individual differences among the females that produced the eggs (Tajima et al., 1999). In the present study, 11 hens and 3 roosters of the Rhode Island Red variety were separated into 3 mating groups, and the hens were inseminated with the semen collected from certain roosters. The resulting fertilized eggs were incubated to reach stages 13 to 16 (staging of Hamburger and Hamilton, 1951), and blood samples collected from individual embryos were analyzed for the number of cPGCs. In Group 3, the total number of cPGCs was higher in the eggs laid by two of the females than in those laid by the other two. Moreover, the total cPGC number contained in the eggs laid by hens in Group 1 increased after the mating rooster was changed. The hens that laid eggs with a high total cPGC number in the embryonic blood often had a low egg-laying ability, and the blood volume in eggs laid by these hens reached a plateau between stages 14 and 15. Three variation patterns of total cPGC number in different individuals could be determined, with peaks at stages 13, 14 and 15, respectively. The results indicate that not only the females that produced the eggs but also the males that provided the sperm influenced the total cPGC number in different individuals.

Keywords

• primordial germ cells
• circulation
• chick embryo
• male
• female