This study was supported by grant 1 RO1 HD-02613, from the National Institutes of Child Health and Human Development, and grants G-24043, GB-6435X, and GB-5024 from the National Science Foundation.
Formation and structure of the hemodichorial chorio-allantoic placenta of the bat (Myotis lucifugus lucifugusy)†
Article first published online: 3 FEB 2005
Copyright © 1968 Wiley-Liss, Inc.
American Journal of Anatomy
Volume 122, Issue 3, pages 453–489, May 1968
How to Cite
Enders, A. C. and Wimsatt, W. A. (1968), Formation and structure of the hemodichorial chorio-allantoic placenta of the bat (Myotis lucifugus lucifugusy). Am. J. Anat., 122: 453–489. doi: 10.1002/aja.1001220303
- Issue published online: 3 FEB 2005
- Article first published online: 3 FEB 2005
The definitive chorio-allantoic placenta of the bat is hemodichorial, since the cytotrophoblast layer persists to term. The syncytium contains intrasyncytial lacunae in which there is a continuous lamina interrupted only where portions of the syncytium communicate with the thin ectoplasmic layer at the surface of the maternal blood spaces.
The future cytotrophoblast and syncytial trophoblast layers can be distinguished shortly after implantation. The future syncytial layer is not syncytial until after it invests most of the anastomotic vessels of the vascular tuft. The resulting labyrinth is converted from the vaso-chorial to the hemodichorial condition as processes of syncytium pass through the basement membrane of the maternal vessels and spread out under the endothelial cells. The basement membrane is then included within the syncytium as the intrasyncytial lamina, and the maternal endothelial cells are lost. The numerous communications of the maternal vessels with the labyrinth seen early in gestation are reduced through occlusion of many of the efferent channels, which process also contributes areas of necrosis to the decidua basalis. The peculiarity of a maternal extracellular membrane being incorporated into the fetal portion of the placenta is discussed.