Embryonic diapause and its regulation.
Embryonic diapause, a condition of temporary suspension of development of the mammalian embryo, occurs due to suppression of cell proliferation at the blastocyst stage. It is an evolutionary strategy to ensure the survival of neonates. Obligate diapause occurs in every gestation of some species, while facultative diapause ensues in others, associated with metabolic stress, usually lactation. The onset, maintenance and escape from diapause are regulated by cascades of environmental, hypophyseal, ovarian and uterine mechanisms that vary among species and between the obligate and facultative condition. In the best-known models, the rodents, the uterine environment maintains the embryo in diapause, while estrogens, in combination with growth factors, reinitiate development. Mitotic arrest in the mammalian embryo occurs at the G0 or G1 phase of the cell cycle, and may be due to expression of a specific cell cycle inhibitor. Regulation of proliferation in non- mammalian models of diapause provide clues to orthologous genes whose expression may regulate the reprise of proliferation in the mammalian context.
Lopes
Flavia L
FL
Centre de Recherche en Reproduction Animale, Facultéde Médecine Vétérinaire, Université de Montréal, 3200 rue Sicotte, St-Hyacinthe, Quebec, Canada J2S7C6.
Desmarais
Joëlle A
JA
Murphy
Bruce D
BD
D000818:Animals; D001755:Blastocyst / Q000502:physiology*; D049109:Cell Proliferation; D010065:Embryo Implantation, Delayed / Q000502:physiology*; D047108:Embryonic Development / Q000502:physiology; D004967:Estrogens / Q000502:physiology; D005260:Female; D005786:Gene Expression Regulation; D006133:Growth Substances / Q000502:physiology; D007774:Lactation; D008322:Mammals / Q000502:physiology*; D010053:Ovary / Q000502:physiology; D011247:Pregnancy; D051381:Rats; D014599:Uterus / Q000502:physiology
D004967:Estrogens; D006133:Growth Substances