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immunocytochemical findings in RSA placentae do not correlate with clinical history or ultrasonographic observations.

EFFECTS OF DIFFERENTIATING AGENTS ON A TROPHOBLAST CELL LINE AS REVEALED BY IN VITRO STUDIES C. Crescimannoa, P. Bischof6, D. Zaccheo’ & M. Castellucci” (“Institute of Anatomy, RWTH Aachen, D-5 100 Aachen, Germany; b Department of Obstetrics and Gynecology, University of Geneva, CH-1211 Geneva. Switzerland and ‘Department of Anatomy, Medical Faculty, I- 16 132 Genoa, Italy)

The human placenta is a complex multifunctional endocrine organ that supports fetal survival and development. The trophoblast produces several hormones and “pregnancy” proteins. Using placental cell lines we have investigated different aspects of their production, particularly in relation to cell differentiation, a key factor in placental development. We cultured the BeWo choriocarcinoma cell line in the presence of various differentiating agents, including retinoic acid, retinal, isobutylmethylxanthine, forskolin and sodium butyr- ate.

These substances have been demonstrated to be essential for control of cell differentiation in many epithelial tissues by different cellular pathways. The results suggest that agents influencing trophoblast differentiation in vitro, are responsible for an increase in hCG production, but not that of other placenta-specific proteins.

CARBONIC ANHYDRASE IN THE PIG PLACENTA, CHANGES IN LOCALIZATION AND INTENSITY DURING GESTATION V. Dantzer, Y. Ridderstrale”, G. Thilander” & H. Rodriguez-Martinez” (Department of Anatomy and Physiology, Royal Veterinary and Agricultural University, DK-1870 Copen- hagen, Denmark and a Departments of Animal Physiology, Anatomy and Histology, The Swedish University of Agricultural Sciences, S-75007 Uppsala, Sweden)

The enzyme carbonic anhydrase (CA) is involved in CO2 transport and excretion, and in transport of ions (H+ and HCOs-) influencing intra- and extracellular acid-base balance. In addition CA can function in metabolic CO2 fixation. The localization ofthis enzyme in the diffuse, folded, epitheliochorial placenta of the pig was therefore investigated.

Endometrial and placental tissue was taken from days 12, 17,26,30,32,40,51,71, 103, 108,112 p.c. and at partus fixed in 3 per cent buffered glutaraldehyde for 3 h, rinsed carefully and embedded in historesin by routine methods. A slightly modified Hansson histochemical method for CA was used (Ridderstrile, 1980, Acta Physiol. &and. (Suppl.), 488).

The maternal capillaries gave a positive reaction for CA, weak at days 12-17, pronounced later on, and irregularly distributed at partus. The fetal capillaries showed no reaction for CA.

The maternal epithelium varied throughout gestation from no reaction at day 12, the preplacental stage, to diffuse and strong from days 17 to 30. At the following stages the reaction was still strong but also localized to distinct granules in the cytoplasm. At later stages