Evidence for crucial role of hindgut expansion in directing proper migration of primordial germ cells in mouse early embryogenesis.
During mouse gastrulation, primordial germ cells (PGCs) become clustered at the base of the allantois and move caudally into the hindgut endoderm before entering the genital ridges. The precise roles of endoderm tissues in PGC migration, however, remain unclear. By using Sox17 mutants with a specific endoderm deficiency, we provide direct evidence for the crucial role of hindgut expansion in directing proper PGC migration. In Sox17-null embryos, PGCs normally colonize in the allantois and then a small front-row population of PGCs moves properly into the most posterior gut endoderm. Defective hindgut expansion, however, causes the failure of further lateral PGC movement, resulting in the immobilization of PGCs in the hindgut entrance at the later stages. In contrast, the majority of the remaining PGCs moves into the visceral endoderm layer, but relocate outside of the embryonic gut domain. This leads to a scattering of PGCs in the extraembryonic yolk sac endoderm. This aberrant migration of Sox17-null PGCs can be rescued by the supply of wildtype hindgut cells in chimeric embryos. Therefore, these data indicate that hindgut morphogenic movement is crucial for directing PGC movement toward the embryonic gut side, but not for their relocation from the mesoderm into the endoderm.
Department of Veterinary Anatomy, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.
Kenshiro
K
Hara
Masami
M
Kanai-Azuma
Mami
M
Uemura
Hiroshi
H
Shitara
Choji
C
Taya
Hiromichi
H
Yonekawa
Hayato
H
Kawakami
Naoki
N
Tsunekawa
Masamichi
M
Kurohmaru
Yoshiakira
Y
Kanai
D000818:Animals; D002465:Cell Movement; D019175:DNA Methylation; D004622:Embryo, Mammalian / Q000166:cytology*; D047108:Embryonic Development; D044127:Epigenesis, Genetic; D005854:Germ Cells / Q000166:cytology*; D024002:HMGB Proteins / Q000235:genetics; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D051379:Mice; D008813:Mice, Inbred ICR; D046529:Microscopy, Electron, Transmission; D055760:SOXF Transcription Factors / Q000235:genetics
D024002:HMGB Proteins; D055760:SOXF Transcription Factors; C511606:Sox17 protein, mouse