In the allantochorionic membrane of the placentomes (cotyledon), the AT2 receptor was also the most abundant Ang II receptor type (Figs. 6a and 7c). Most binding occurred on the mesenchymal cells at the fetal side of the cotyledon and at the lower-order fetal villi (Fig. 6a). This binding disappeared in the higher-order villi. Specific binding to the tunica media of the arteries was observed in only a few arteries and was always scarce.
Again, no Ang II receptor expression was observed on the allantoic endo-derm and trophoblast cells. No binding of 125I-[Sar1-Ile5-Ile8]-Ang II was demonstrated in relation to the bovine placental lactogen-producing binucleate and trinucleate cells in the trophoblast cell layer and maternal uterine epithelium (Fig. 8). On the maternal side of the placentome (caruncle), the lamina propria of the endometrium and the lower-order septa of the maternal crypts showed binding (Fig. 6b). In contrast to the fetal compartment, the main Ang II receptor type in the maternal constituent was the AT1 receptor (Figs. 6b and 7d). No binding was found on the higher-order septa of the maternal crypts. The binding in the mesenchymal tissue revealed a characteristic patchy pattern (Fig. 9), as most silver grains accumulated in close relationship to nuclei of mesenchymal cells. cialis professional
FIG. 6. Autoradiograms showing the distribution of 125I-[Sar1-Ile5-Ile8]-Ang II binding in serial cryosections of a bovine placentome (Day 145). Dark regions indicate high density of labeled receptors. a) Binding in the presence of losartan showing AT2 receptors. b) Binding in the presence of PD 123319 showing AT1 receptors. c) Total binding. d) Binding in the presence of 1 ^M unlabeled [Sar1-Ile5-Ile8]-Ang II. F, Fetal side; solid arrows, mesenchyme of fetal villi; M, maternal side; open arrows, maternal crypt wall. Bar = 1000 ^m.
FIG. 7. Detail of serial cryosections of a bovine placentome (Day 152). a) Bright-field view of a hematoxylin and eosin-stained section. b-f) Brightfield photomicrographs combined with epipolarised light of emulsion-dipped sections. Bright grains indicate the presence of125I-[Sar1 -Ile5-Ile8]-Ang II-labeled receptor. b) Total binding. c) Binding in the presence of lo-sartan, demonstrating AT2 receptors. d) Binding in the presence of PD 12331 9, demonstrating AT1 receptors. e) Binding in the presence of both PD 123319 and lo-sartan, demonstrating non-AT1/non-AT2 binding sites. f) Binding in the presence of 1 ^M unlabeled [Sar1-Ile5-Ile8]-Ang II. M, maternal crypt; F, fetal villus; solid arrows, trophoblast cells covering the fetal villi; open arrows, uterine epithelium covering the maternal crypt. Bar = 75 ^m