Table of Contents
Advances in Biology
Volume 2014 (2014), Article ID 639274, 21 pages
http://dx.doi.org/10.1155/2014/639274
Review Article

Placental Evolution within the Supraordinal Clades of Eutheria with the Perspective of Alternative Animal Models for Human Placentation

Department of Surgery, Faculty of Veterinary Medicine and Animal Science, University of Sao Paulo (FMVZ-USP), Avenida Prof. Dr. Orlando Marques de Paiva 87, 05508-270 Sao Paulo, SP, Brazil

Received 15 June 2014; Accepted 22 September 2014; Published 23 October 2014

Academic Editor: Hong-Bo Zhao

Copyright © 2014 Andrea Mess. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Here a survey of placental evolution is conducted. Placentation is a key factor for the evolution of placental mammals that had evolved an astonishing diversity. As a temporary organ that does not allow easy access, it is still not well understood. The lack of data also is a restriction for better understanding of placental development, structure, and function in the human. Animal models are essential, because experimental access to the human placenta is naturally restricted. However, there is not a single ideal model that is entirely similar to humans. It is particularly important to establish other models than the mouse, which is characterised by a short gestation period and poorly developed neonates that may provide insights only for early human pregnancy. In conclusion, current evolutionary studies have contributed essentially to providing a pool of experimental models for recent and future approaches that may also meet the requirements of a long gestation period and advanced developmental status of the newborn in the human. Suitability and limitations of taxa as alternative animal models are discussed. However, further investigations especially in wildlife taxa should be conducted in order to learn more about the full evolutionary plasticity of the placenta system.