Summary. Cells from the labyrinth region of the developing rat chorioallantoic placenta were able to differentiate in vitro into cells capable of producing placental lactogen. Progesterone selectively inhibited placental lactogen production by labyrinth cell cultures undergoing differentiation but had no apparent effect on lactogen production by mature trophoblast giant cells. The measurement of placental lactogen production is a useful method for monitoring the functional differentiation of rat trophoblast cells in vitro.
M. J. Soares and S. R. Glasser
S. J. Kimber, I. M. Illingworth and S. R. Glasser
Monoclonal antibodies were used to examine the expression of a number of carbohydrate antigens in the rat endometrial epithelium from day 1 to day 8 of pregnancy and in ovariectomized rats supplemented with ovarian steroids. Carbohydrate antigens based on the Galβ1–GlcNAc backbone structure were expressed and some of these (Ley, Lex, B antigen) were present at all stages of pregnancy and independent of ovarian steroids. The H-type-2 antigen was stimulated by progesterone and expressed in the sensitized and receptive uterus, but was not detected after implantation or, in ovariectomized rats, in the refractory phase. The H-type-1 antigen, which is stimulated by oestrogen in the mouse, appeared to be stimulated by progesterone in rats. It was expressed throughout the period of pregnancy but maximal expression was found on days 4–5. The histo-blood group A antigen appeared in ovariectomized rats only after treatment with progesterone followed by three daily injections of progesterone and oestrogen, and in the corresponding postimplantation period of pregnant rats. Its appearance corresponded to the loss of detectable H-type-2 antigen. This study shows that the rat endometrial epithelium expresses some carbohydrate antigens not expressed in mice (A and antigen) or under completely different steroidal regulation (H-type-1). Moreover, the antigen was expressed on the endometrial epithelium adjacent to decidua on days 7 and 8 of pregnancy, but not in rats given ovarian steroids to mimic the sensitized, receptive or refractory phase. Differences in expression between glandular and luminal epithelia indicated differences in steroidal regulation, as found in mice.
C. J. P. Jones, J. D. Aplin, J. Mulholland and S. R. Glasser
Lectin histochemistry was used to demonstrate changes in the surface glycan distribution of uterine stromal cells as they differentiate to form decidual cells. Decidualization was induced in hormone-treated, ovariectomized rat uteri by needle scratch. Uterine tissue from days 2 to 8 of deciduoma development was examined with a panel of lectins specific for terminal nonreducing structures in N- and O-linked classes of glycoprotein glycan, including α2,3- and α2,6-linked sialic acid residues. Immunostaining for desmin was used to identify decidual cells. An increase in N-linked glycans associated with the cell surface and recognized by lectins from Phaseolus vulgaris (leukoagglutinin) (1-PHA), Pisum sativum (PSA) and Triticum vulgaris (WGA) was found during the early growth of decidual cells. As decidualization progressed regionally from the antimesometrial to mesometrial uterus, an increase in α2,3-linked sialic acid residues was followed by a loss of the α2,6-linked form. The results suggest that as stromal cells differentiate, glycoprotein biosynthesis and glycosyl transferase activity are altered. These changes in patterns of glycosylation may give rise to altered decidual cell–matrix and cell–cell interactions during differentiation and play a role in the modulation of decidual cell interactions with trophoblast during early placentation.