Jonathan T. Lanman

Delayed implantation of the blastocyst: An exploration of its effects on the developing embryo☆

Abstract Embryonic diapause is a common phenomenon in nature, exemplified in the dormancy of plant seeds, in the ability of birds eggs to withstand delay before incubation, and in delayed implantation of the blastocyst in a variety of mammals and blastocyst arrest in certain marsupials. Available evidence on the effects of delay on the embryo and fetus is very limited. The pertinent observations indicate that such delays are usually not harmful to the embryo. Under certain conditions, mammalian blastocysts in delay may be destroyed, but no clear instances of defective development have been reported. Certain animals offer attractive experimental possibilities, and further work might reveal something more of the control mechanisms over development under the unusual conditions of embryonic diapause.