%0 Journal Article
%T The subplacenta of the red-rumped agouti (Dasyprocta leporina L)
%A Rosangela Rodrigues
%A Anthony M Carter
%A Carlos Ambrosio
%A Tatiana dos Santos
%A Maria Miglino
%J Reproductive Biology and Endocrinology
%D 2006
%I BioMed Central
%R 10.1186/1477-7827-4-31
%X Placentae were collected from early in midgestation to near term of pregnancy and examined by standard histological techniques, immunohistochemistry and transmission electron microscopy. In addition, to study the microvasculature of the subplacenta, vessel casts were inspected by scanning electron microscopyIn the subplacenta, lamellae of connective tissue support a layer of mononuclear cytotrophoblast cells. Beneath this is found syncytiotrophoblast. Clusters of multinuclear giant cells occur in the transition zone between the subplacenta and decidua. There are prominent intercellular spaces between the cytotrophoblast cells. The basal membrane of these cells is often close to fetal blood vessels. The syncytiotrophoblast surrounds an extensive system of lacunae. Microvilli project into these lacunae from the plasma membrane of the syncytiotrophoblast. The syncytial cytoplasm contains electron-dense granules. This is probably the amylase-resistant PAS-positive material identified by histochemistry. The subplacenta is supplied entirely from the fetal circulation. Within it the vessels pursue a tortuous course with sinusoidal dilatations and constrictions.The functions that have been attributed to the subplacenta include hormone production. Our findings are consistent with this interpretation, but suggest that hormone secretion is directed towards the fetal circulation rather than the maternal tissues.The hystricognath rodents (Suborder Hystricomorpha, Infraorder Hystricognathi [1]) appeared in the Eocene and underwent an extensive radiation in the Miocene. At this time they were able to capitalize upon the emergence of grasslands for which they were well adapted in a number of ways [2]. They differ from other rodents in giving birth to precocial young. The newborn is well developed with open eyes and a full coat of hair [3]. This reproductive strategy requires a lower rate of energy consumption and is well suited to an herbivorous diet [2]. The hystricognath placenta
%U http://www.rbej.com/content/4/1/31