Evolutionary Patterns of Maternal Recognition of Pregnancy and Implantation in Eutherian Mammals
Henrique Bartolomeu Braz,
Rodrigo da Silva Nunes Barreto,
Leandro Norberto da Silva-Júnior,
Bianca de Oliveira Horvath-Pereira,
Thamires Santos da Silva,
Mônica Duarte da Silva,
Francisco Acuña,
Maria Angelica Miglino
Affiliations
Henrique Bartolomeu Braz
Ecology and Evolution Laboratory, Butantan Institute, São Paulo 05503-900, SP, Brazil
Rodrigo da Silva Nunes Barreto
Department of Animal Morphology and Physiology, Faculty of Agricultural and Veterinary Sciences, São Paulo State University, Jaboticabal 14884-900, SP, Brazil
Leandro Norberto da Silva-Júnior
Department of Surgery, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo 05508-270, SP, Brazil
Bianca de Oliveira Horvath-Pereira
Department of Surgery, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo 05508-270, SP, Brazil
Thamires Santos da Silva
Department of Surgery, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo 05508-270, SP, Brazil
Mônica Duarte da Silva
Department of Surgery, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo 05508-270, SP, Brazil
Francisco Acuña
Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata, La Plata B1900, Argentina
Maria Angelica Miglino
Department of Veterinary Medicine, University of Marília, Marília 17525-902, SP, Brazil
The implantation of the embryo into the maternal endometrium is a complex process associated with the evolution of viviparity and placentation in mammals. In this review, we provide an overview of maternal recognition of pregnancy signals and implantation modes in eutherians, focusing on their diverse mechanisms and evolutionary patterns. Different pregnancy recognition signals and implantation modes have evolved in eutherian mammals, reflecting the remarkable diversity of specializations in mammals following the evolution of viviparity. Superficial implantation is the ancestral implantation mode in Eutheria and its major clades. The other modes, secondary, partially, and primary interstitial implantation have each independently evolved multiple times in the evolutionary history of eutherians. Although significant progress has been made in understanding pregnancy recognition signals and implantation modes, there is still much to uncover. Rodents and chiropterans (especially Phyllostomidae) offer valuable opportunities for studying the transitions among implantation modes, but data is still scarce for these diverse orders. Further research should focus on unstudied taxa so we can establish robust patterns of evolutionary changes in pregnancy recognition signaling and implantation modes.
