Delayed Implantation or Embryonic Diapause is a reproductive strategy used by approximately 100 different mammals in seven or eight different orders. In embryonic diapause, the embryo (blastocyst) does not immediately implant in the uterus, but is maintained in a state of dormancy. Little to no development takes place while the embryo remains unattached to the uterine wall. As a result, the normal gestation period is extended for a species-specific period of time. While much of the molecular regulation involved in activating dormant blastocysts has been characterized, little is still known about entry into diapause, and the conditions which enable a blastocyst to remain dormant.
Some mammals that undergo embryonic diapause include rodents, bears, mustelids (e.g. badgers), and marsupials, (e.g. kangaroos). Some groups only have one species that undergoes embryonic diapause, such as the roe deer in the order Artiodactyla.
Famous quotes containing the word embryonic:
“Quintilian [educational writer in Rome around A.D. 100] thought that the earliest years of the child’s life were crucial. Education should start earlier than age seven, within the family. It should not be so hard as to give the child an aversion to learning. Rather, these early lessons would take the form of play—that embryonic notion of kindergarten.”
—C. John Sommerville (20th century)