The evolution of placentas in poeciliid fishes is associated with conception of overlapping litters and male mating strategies becoming more coercive. Sperm competition in ovaries of multiply-inseminated females may favor fertilization of immature eggs during ongoing pregnancies.

Pregnancy-specific glycoproteins (PSGs) are major placental proteins essential for the maintenance of normal gestation. However, little is known about their gene expression regulation during placentation. It was previously demonstrated that the human core promoter binding protein recently renamed Krüppel-like factor (KLF) 6 binds to a highly conserved sequence within the PSG promoters and is ma...

Placentation disorders are the result of impaired embedding of the placenta in the endometrium. The prevalence of these disorders is estimated to be around 0.3 %. A history of previous prior uterine surgery (especially cesarean section and curettage) is the most common risk factor. Impaired placentation is differentiated into deep placental attachment; marginal, partial and total placenta previ...

Most studies on the evolution of viviparity in squamate reptiles have focused on one or more of the following questions: (1) what selective force(s) are involved in the transition from oviparity to viviparity? (2) how does this transition occur (i.e., what changes are involved)? and (3) how and when does placentation evolve? In answer to the first of these questions, most studies have implicate...

Implantation in the beaver is superficial and antimesometrial. The embryonic disc occupies one side of the flattened mesometrial hemisphere of the large blastocyst. A n endometrial papilla, unique to the beaver, forms on the mesometrial uterine wall just prior to chorioallantoic contact. The reniform placenta then develops around this papilla. Amniogenesis is by folding. A transient choriovitel...

Organ development occurs through the coordinated interaction of distinct tissue types. So, a question at core understanding evolution new organs is, how do tissue-tissue signalling networks arise? The placenta is great model for organs, because placentas have evolved repeatedly, relatively recently in some lineages, and exhibit intermediate forms extant clades. Placentas, like other form from t...