197 HYSTRICOMORPH SUBPLACENTA: THE COMPARATIVE ASPECTS
M.A. Miglino A , M. Bonatelli A , M.C. Lima A , M.F. Oliveira B , R.F. Rodrigues A , R.G. Carvalho C A , C.E. Ambrósio A , M.R.F. Machado D and A.M. Carter EA FMVZ – Sao Paulo University, Sao Paulo, Brazil
B Mossoró Superior School of Agriculture, Rio Grande de Norte, Brazil
C UNESP – Aracatuba, Sao Paulo, Brazil
D UNESP – Jaboticabal, Sao Paulo, Brazil
E Department of Physiology and Pharmacology, University of Southern Denmark, Idense, Denmark. Email: miglino@usp.br
Reproduction, Fertility and Development 17(2) 249-249 https://doi.org/10.1071/RDv17n2Ab197
Submitted: 1 August 2004 Accepted: 1 October 2004 Published: 1 January 2005
Abstract
Placentae of four hystricimorph rodents – capybara (Hydrochaerus hydrochaeris), agouti (Dasyprocta aguti), paca (Agouti paca), and rock cavy (Kerodon rupestris) – were examined by conventional histology, transmission electron microscopy, and scanning electron microscopy. In all of these animals, the subplacenta comprised cytotrophoblasts, supported on lamellae of allantoic mesoderm, and syncytiotrophoblasts. The subplacenta of paca, agouti, and rock cavy had a structure similar to that of capybara, although it was not clearly separated from the main placenta by a layer of mesenchyme. The subplacenta of agouti was examined by conventional histology and found to have a structure similar to that in capybara and paca. The cytotrophoblasts were separated by true extracellular spaces; these cells were characterized by the presence of numerous mitochondria, a large-size nucleus relative to the cytoplasm, and absence of glycogen and lipid (PAS-negative). Also, the morphology of the syncytiotrophoblasts was similar in all of these animals; these cells were PAS-positive, and were characterized by the presence of numerous spherical electron-dense granules distributed throughout the cytoplasm, presence of large accumulations of glycogen, few mitochondria, golgi apparatus and granular ER. In addition, the syncytium contained lacunae lined by microvilli, observed only by transmission electron microscopy. The subplacenta is supplied by a single fetal artery. The vessels within the subplacenta pursue a tortuous course with dilatations and constrictions as in an endocrine gland. In mid-to-late gestation, the subplacenta is supplied largely by fetal vessels. A large branch of the umbilical artery follows the central band of fetal mesenchyme to the base of the main placenta and then branches to supply the subplacenta. The subplacental vessels pursue a tortuous course with dilatations and constrictions as in an endocrine gland such as the ovary. A few branches of the maternal artery supply the subplacenta, at least in capybara and paca, where they can be demonstrated by latex injection.
This work was supported by FAPESP, Sao Paulo, Brazil, and CNPq, Brazil.
