The placenta of the four‐eyed opossum (philander opossum)Philander opossum)

  title={The placenta of the four‐eyed opossum (philander opossum)Philander opossum)},
  author={Allen C. Enders and Robert K. Enders},
  journal={The Anatomical Record},
The placental membranes of the four‐eyed opossum were studied by light and electron microscopy. The individual fetuses in each uterus were surrounded by amnion, had allantoic sacs of approximately the same size as each fetus, and were situated in a common yolk sac cavity. The extent of the choriovitelline placenta was marked by a prominent sinus terminalis, and at this margin there was a region where the trophoblast cells penetrated folds of the endometrium. Elsewhere the choriovitelline… Expand
Ultrastructure of the placenta of the tammar wallaby, Macropus eugenii: comparison with the grey short‐tailed opossum, Monodelphis domestica
The extended secretory phase of the tammar uterus and the maternal recognition of early pregnancy appear to be derived characters of macropodid marsupials. Expand
The allantois of the north american opossum (didelphis virginiana) with preliminary observations on the yolk sac endoderm and trophectoderm
The opossum allantois functions primarily in the storage of urinary wastes during prenatal life, and it is thought that exchange between the developing fetus and mother occurs primarily through the activity of cells that form the trophoblast. Expand
Ultrastructure of the placenta of Antarctic seals during the first third of pregnancy.
The chorioallantoic placenta from six crabeater seals and two leopard seals was lobulated, zonary, labyrinthine and endotheliochorial, and it is suggested that the deposits of granular bodies show the sites of iron storage in the placentas. Expand
Ultrastructural observations on the chorioallantoic placenta of the golden-rumped elephant shrew, Rhynchocyon chrysopygus
Electron-dense particles resembling iron deposits are demonstrable in the fetal mesenchyme of the labyrinthine zone of the elephant shrew. Expand
Early ontogeny and placentation of the grey short‐tailed opossum, Monodelphis domestica (Didelphidae: Marsupialia): contribution to the reconstruction of the marsupial morphotype
The results of this study provide the first detailed ultrastructural description of a trophoblastic syncytium in a marsupial and the first original documentation of an invasive trophectoderm and an inflammatory reaction at parturition in M. domestica. Expand
Review: Marsupials: placental mammals with a difference.
Despite the relatively short period of placentation, it is clear that the trophoblast and the placenta it forms are as important for successful pregnancy in marsupial as in eutherian mammals. Expand
Placentation in mammals: Definitive placenta, yolk sac, and paraplacenta.
It is found that paraplacental structures, while showing less variation than the placenta proper, contribute not just to the integrity of overall placentation, but in various ways to maternal-fetal interrelationships. Expand
The fine structure of the chinchilla placenta.
The structure of the placental labyrinth, interlobular or "coarse" syncytium, visceral (splanchnopleuric) yolk sac, giant cells and subplacenta of the chinchilla was studied with the electron microscope and was found to be hemomonochorial. Expand
Ultrastructural Changes in the Uterine Luminal and Glandular Epithelium during the Oestrous Cycle of the Marsupial Monodelphis domestica (Grey Short-Tailed Opossum)
Ultrastructural changes in the endometrium associated with the oestrous cycle were studied in the South American marsupial Monodelphis domestica, where solitary cilia are only found in the immature uterus or after ovariectomy and mechanisms for the remodelling of the luminal and glandular epithelium are especially conspicuous. Expand
Gestation and placentation in two New World opossums: Didelphis virginiana and Monodelphis domestica.
Gestation and placentation, including the ultrastructural features of trophoblastic apposition to the uterine mucosa, are very similar in Didelphis and Monodelphis, providing a basis for comparison in future studies of didelphid marsupials. Expand


Development of structure and function in the mammalian yolk sac. I. Developmental morphology and vitamin B12 uptake of the rat yolk sac.
The present findings indicate that the visceral yolk sac possesses a highly specific mechanism for accumulating considerable vitamin B12 and B12-intrinsic factor complex in vitro and suggests that this placental membrane in the rat may be highly specialized for the transfer of macromolecules. Expand
An electron microscopic visualization of transport across rat visceral yolk sac.
  • R. Lambson
  • Biology, Medicine
  • The American journal of anatomy
  • 1966
Transport of large protein molecules through visceral endodermal cells involves an apical tubular system, large storage vacuoles, and smaller vesicles which appear to migrate basally near the end of pregnancy, when normally antibodies are being transferred in the largest quantities to the fetus. Expand
Development of structure and function in the mammalian yolk sac. II. Vitamin B12 uptake by rabbit yolk sacs.
Intrinsic factor, with a species specificity similar to that observed in fetal and adult intestine, stimulated B12 uptake severalfold and depressed the uptake of B12 when DNP or iodoacetate was added to the incubation medium. Expand
Cytological aspects of trophoblast-uterine interaction in early implantation.
It is suggested that the capacity of trophoblast to form junctions with epithelial cells is an important part of the implantation process, facilitating penetration of the endometrium without dislodgment of the blastocyst. Expand
Fluid transport in the rabbit gallbladder. A combined physiological and electron microscopic study.
It is concluded that the intercellular compartment fulfills the conditions for the middle compartment of the Curran model and that active transport of solute across the lateral plasma membrane into the inter cellular space may be responsible for fluid absorption by the gall bladder. Expand
The Mammals of North America
The mammals of North America , The mammals of North America , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی