Apoptosis in mouse embryos: elevated levels in pregastrulae and in the distal anterior region of gastrulae of normal and mutant mice.
The pattern of apoptotic cell death has been surveyed in prestreak and primitive streak embryos of four strains of mice and in three mutants affecting gastrulation. In C57BL/6 embryos, a high level of cell death occurs in the early egg cylinder stage at embryonic day 5 (E5) to E5.5. In all strains, cell death is elevated shortly before gastrulation, but the level varies four- to fivefold among strains. During gastrulation, cell death declines but is relatively more abundant in the distal and distal anterior regions. Early streak embryos cultured in media with reduced levels of growth factors show increased cell death mainly in the distal region. In three mutants with disturbed function of the proximal visceral endoderm and/or primitive streak, cell death is increased, and the regional pattern seen in normal embryos is intensified. The results strongly suggest that the proximal visceral endoderm and primitive streak region are the principal sites of synthesis of growth factors promoting cell survival. We conclude that localized growth factor supply has an important role in regulating the size of the embryo and of embryonic regions.
Manova
K
K
Department of Cell Biology, Cornell University Medical College, New York, New York 10021, USA.
Tomihara-Newberger
C
C
Wang
S
S
Godelman
A
A
Kalantry
S
S
Witty-Blease
K
K
De Leon
V
V
Chen
W S
WS
Lacy
E
E
Bachvarova
R F
RF
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D002455:Cell Division / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000235:genetics; D005314:Embryonic and Fetal Development; D005260:Female; D005775:Gastrula / Q000166:cytology*; D018507:Gene Expression Regulation, Developmental; D006133:Growth Substances / Q000494:pharmacology; D051557:Hepatocyte Nuclear Factor 4; D020287:In Situ Nick-End Labeling; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008813:Mice, Inbred ICR; D008817:Mice, Mutant Strains; D009154:Mutation / Q000502:physiology; D010750:Phosphoproteins / Q000235:genetics; D011247:Pregnancy; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics
D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D006133:Growth Substances; D051557:Hepatocyte Nuclear Factor 4; D010750:Phosphoproteins; C501970:Tcfl4 protein, mouse; D014157:Transcription Factors