Erythrophagocytosis by cells of the trophoblastic epithelium in the sheep placenta in different stages of gestation

Abstract

Erythrophagocytosis by the trophoblastic epithelial cells of the sheep placenta was studied in different stages of gestation. Light-microscopic observations showed that the erythrophagocytosis became more and more conspicuous with increasing stages of gestation. Electron-microscopically, this process appeared to take place in the same way as described for red cell destruction elsewhere. Light-microscopically, a high acid phosphatase activity could be demonstrated in the cells which took part in the process of erythrophagocytosis. Degenerating epithelial cells were found, the number of which appeared to increase with the stage of gestation. Under the electron microscope, the cytoplasm of these degenerating cells appeared to contain a diversity of crystals, myelin-like figures and irregular coarse concretions.

Light- and electron-microscopic study of the near-term paraplacenta of the domestic cat

“…The cells added to the free polar zone may be induced to differentiate and participate in the transfer of substances from the uterine epithelium by the apposition to the latter [Bjórkman, 1957;Enders and Schlafke, 1969], As demonstrated by the many mitotic figures, the cuboidal cytotrophoblast in the junctional area has a proliferative cell popu lation and gives rise to the adjacent hemophagous columnar trophoblast, some cells of which slough into the uterine cavity and degenerate [Leiser and Enders, 1980]. Possibly this degeneration is due in part to an overcharge of phagosomes, leading to exhaustion of the lysosomal apparatus, as suggested for the sheep [Myagkaya and Vreeling-Sindelarova, 1976], However, the majority of the cells at the conclusion of their ingestive and digestive activities revert to resting cuboidal trophoblast. Although a number of morphological signs of transition to syncytium occur in this location [ Wislocki and Dempsey, 1946;Wynn, 1973;Schlafke and Enders, 1975;Hernandez-Verdun and Bouteille, 1976;Contractor el al., 1977], it cannot be determined whether the syncy tium arises only from the resting cuboidal trophoblast or the more proliferative dif ferentiated cuboidal trophoblast.…”

Trophoblast cells of ruminant placentas—A minireview

“…Microscopic accumulations of uterine milk secreted by endometrial glands in this region are phagocytized by the trophoblast cells (Schlafer et al, 2000). Similarly, mononucleate trophoblast cells lining the arcade zones (located towards the fetal side, between the bases of cotyledonary villi) of the placentomes are involved in phagocytosis of macromolecules especially erythrocytes (Burton et al, 1976;Myagkaya and Vreeling-Sindelarova, 1976;Santos et al, 1996;Pereira et al, 2001). Extravasated maternal blood which escapes from the capillaries and other larger vessels (Burton et al, 1976) accumulates in the maternal-foetal interface at the arcade zone resulting in the formation of haematomas, from which the maternal blood cells are engulfed by the trophoblasts.…”

Caracterização das áreas hemófagas da placenta bovina

“…A função da eritrofagocitose, observada após o extravasamento de sangue na região do topo dos vilos maternos, é indefinida em várias espécies. Na ovelha, este processo foi muito estudado e ocorre na zona arcada do placentônio, região onde o processo é realizado pelo trofoblasto (Burton et al 1976, Myagkaya & Vreeling-Sindelarova 1976, Myagkaya & Schellens 1981, Myagkaya & De Bruijn, 1982, King 1982, , , , , Myagkaya et al 1984, Murai & Yamauchi 1986, Santos et al 1996. Vários estudos têm sido realizados, visando a esclarecer este mecanismo da passagem de ferro para o feto.…”