Abstract: 414

FREQUENCY, ULTRASTRUCTURAL FEATURES, AND RELEVANCE OF APOPTOSIS IN THE BOVINE PLACENTA.

Christiane Pfarrer¹ , Christina Wirth² , Gerhard Schuler² , Karl Klisch¹ , Rudolf Leiser¹ , Bernd Hoffmann^{2 *}
Institute of Veterinary Anatomy, Justus Liebig Univ, Giessen, Germany ¹
Clinic for Obstetrics, Gynecology and Andrology, Justus Liebig Univ, Giessen, Germany ²

Binucleated trophoblast giant cells (TGC) are characteristic of the bovine epitheliochorial placenta. TGC migrate towards the uterine epithelium and fuse with epithelial cells. Thus, the TGC products (placenta lactogen and pregnancy-specific-proteins) are delivered to the maternal compartment via degranulation, but the resulting trinucleated hybrid cells degenerate quickly, showing signs of apoptosis when examined lightmicroscopically. To define the role of apoptosis for placental function in cattle, placentomes of different gestational stages (d 150, 220, 240, 270, n = 3) and at parturition (n = 3) were screened for apoptosis by in situ-end-labeling of the fragmented DNA. The total number of apoptotic cells was determined for three different locations, basal plate area, intermediate zone and chorionic plate area and the differences were tested for statistical significance. The apoptotic character of the degenerating cells was verified by transmission electron microscopy. Apoptosis was observed in all cell populations throughout gestation. The number of apoptotic cells did not differ significantly among the three zones, but varied significantly between the gestational stages. Lowest numbers (Mean ± SEM) were found at d 150 (17.18 ± 6.5), highest at d 220 (93.96 ± 45.62), whereas numbers drop until d 240 (35.7 ± 32.95). Slowly rising amounts were observed until d 270 (44.96 ± 28.95) and parturition (47.11 ± 9.12). Ultrastructural examination revealed condensation of chromatin, membrane blebbing, and apoptotic bodies. During bovine gestation apoptosis may be involved in placental remodeling and tissue homeostasis, whereas apoptosis near term may be a mean to eliminate cells producing progestagenic signals. Funded by the German Research Foundation (DFG).

    This abstract is being presented on Tuesday, August 3 at 8:00 AM to 10:15 AM at CUB 2nd Floor Ballroom.