�ber die funktionelle Differenzierung des Zottensyncytiums in der menschlichen Placenta

Mature placental material of full-term spontaneous births and 4-, 6-, 8- and 10-week-old placentas obtained from curettage cases were fixed in glutaraldehyde and osmium tetroxide for SEM examination. In young placentas, the ramifications of the chorionic villi start in the form of buds. The buds are transformed into tendrils with swollen extremities. These swellings resemble buds ready to bloom. The villi intertwine in different positions; both the villi and their tendrils are covered with dense layers of microvilli. In mature placentas, the surfaces of the chorionic villi and their ramifications are covered with microvilli. However, in comparison with the microvilli of young placentas, the microvilli here are less numerous and shorter. Imaginations were clearly visible on the surfaces of the villi; younger and newly budding microvilli, similar to those observed in young placentas, were seen in the invaginated regions. We had the impression that the mature placentas must regenerate in order to meet the increasing physiological requirements of the fetus.

Section: Discussionsupporting

confidence: 54%

Scanning electron-microscopic observations on the surfaces of chorionic villi of young and mature placentas

Demir¹

1979

“…11). These findings confirm the results of Lister [1964], [1969], Kaufmann [1972], Schiebler [1972] and Bartel [1975. 1976], Whereas Boyd et al [1968] called the cytoplasmic projections on the free surface of syncytial cells 'syncytial scallops', Kawahara [1960] suggested that these cytoplasmic projec tions were related with the secretion of the apocrine gland.…”

Section: Discussionsupporting

confidence: 82%

“…12). We share the opinion that Langhans" cell nuclei are less dense than syncytiotrophoblast cell nuclei [Lister, 1964;Enders, 1965: Boyd et al, 1968: Kaufmann, 1972Bartel, 1975. 1976],…”

Section: Discussionmentioning

confidence: 99%

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Ultrastructure of the epithelium of the chorionic villi of the human placenta

Demir¹

1980

Human placenta samples obtained at 4, 6, 8 and 10 weeks of gestation and at full term were studied by transmission electron microscopy (TEM). The chorionic villi at early stages of gestation exhibited abundant microvilli on the free surface of the syncytium. The chorionic villi at full term were covered by syncytium which bore short microvilli on its free surface. The syncytial cells were remarkably higher in density than Langhans’ cells. In the earlier period of gestation, a dividing membrane was noticed in the inside of the syncytial cells. The cytoplasm of the syncytial cell contained comparatively small mitochondria, well-developed endoplasmic reticulum cells, ill-developed Golgi systems, electron-dense lipoid droplets and plenty of ribosomes. A great number of Langhans’ cells were noticed in early gestation; only very few were noticed the later part. Mitochondria of Langhans’ cells were comparatively large and the Golgi system was well-developed in the first trimester. Endoplasmic reticulum was less well developed and there were few ribosomes. The basement membrane tendend to become thicker a pregnancy proceeded and lamellar structures appeared on its inner face.

“…Comparing the mean thick ness of the haemal barrier in the guinea pig placenta with that in the human placenta, the guinea pig placenta has a much smaller mean intervascular distance. In the guinea pig placenta we measured a mean thickness of 1.5 pm, whereas in the human placenta this distance is between 3 and 6 pm [H/wlocki and Dempsey, 1955;Aherne and Dunnill, 1966;Kaufmann and Stegner, 1972]. It might thus be possible that the histological structure of the labyrinth does not leave suf ficient room for a further decrease in the barrier thickness.…”

Section: Discussionmentioning

confidence: 99%

Compensation Mechanisms for Experimental Reduction of the Functional Capacity in the Guinea Pig Placenta

Fl¹

1981

The functional capacity of the placenta of the guinea pig has been reduced in four different ways. It has been investigated whether changes in the trophoblast of the labyrinthine part of the placenta occurred which could be interpreted as a compensation mechanism for the reduction of the capacity. No significant decrease of the thickness of the maternofetal barrier could be measured nor did enlargement by microvilli of the apical and basal surface of the syncytium change significantly. Activities of the enzymes glucose-6-phosphate dehydrogenase, lactate dehydrogenase, glucose-6-phosphatase and adenosine triphosphatase showed a great variation, but no differences in activities could be demonstrated. Further, the number of cytotrophoblastic cells was widely spread and no significant difference could be observed, although sometimes large and apparently newly formed parts of lobulus were observed.