ISSN:
0003-276X
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
The chorioallantoic placental barrier of the vampire bat Desmodus rotundus murinus has been studied by electron microscopy. The following elements of the placental labyrinth separate the maternal and fetal circulations: (1) An initially continuous but later discontinuous maternal endothelium, (2) a discontinuous amorphous interstitial membrane, (3) syncytial trophoblast, (4) cytotrophoblast intermingled with a few light cells, (5) a thick basement membrane, (6) mesenchyme, and (7) fetal endothelium. The mesenchyme as a constituent of the barrier is partly bypassed by fetal capillaries. The maternal endothelial cells diminish in number as gestation proceeds, but the interstitial membrane persists. Cytoplasm from the syncytium penetrates defects in the membrane, replaces the lost maternal endothelium, and forms membrane bounded compartments above the former interstitial membrane, which becomes now mainly an intrasyncytial structure. The endotheliochorial relationship originally existing is gradually converted into a hemodichorial condition, if the continuing presence of the amorphous membrane of initially maternal origin is disregarded. The definitive structure of the allantoic placental barrier thus differes somewhat from the organization earlier proposed by one of us on the basis of light microscopic observations. The persistence of an intrasyncytial lamina derived at least initially from maternal tissue is a novel if not a unique feature of the placenta in higher Chiroptera.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/ar.1091620108
