The invasion of the syncy-tiotrophoblast into the stromal tissue of the endometrium could be seen as “finger-like” projections of tissue displaying multinucleated cells typical of syncytium. This cell layer surrounded the blood vessels underlying the apical endometrial epithelium, which had undergone a typical hypertrophy and proliferative response (Fig. 2B). By comparison, the apical endometrium of a nonpregnant marmoset showed no hypertrophy of blood vessels, and the endometrium was of regular appearance (Fig. 2A). The decidual reaction in the marmoset monkey is minor compared to that of other primates, so the lack of a decidual reaction in Figure 2B did not necessarily indicate that the animal was not pregnant. buy cheap antibiotics
Histology of Uteri after Parthenogenetic Embryo Transfer
In the two females that displayed biochemical evidence of pregnancy (469W and 491W), there was also histological evidence of implantation, although in both cases the morphology was distinct from that of females pregnant with biparental IVF embryos. In cross sections of the uterus of 491W (Fig. 2D), a plaque of tissue was observed near the apical surface of the endometrium, and presumptive syn-cytiotrophoblast surrounded blood vessels underlying the epithelium. Syncytial tissue in the stroma, similar to that seen in the normal pregnant animals, was observed. Although remnants of membranes were present on the surface of the endometrium, a definite membrane could not be determined, and there was no discernible fetal tissue. Also present were mitotic bodies, which indicate the continued proliferation of syncytial trophoblast despite the degeneration of the fetal tissue. Cross sections of the uterus of female 469W (Fig. 2C) also exhibited a plaque of putative trophectoderm and a more distinct decidual reaction. Epithelium near the plaque was disorganized, but neither placental membranes nor fetal tissue was observed. Syncytium, which had histology very similar to that seen in normal pregnant animals, was underlying the endometrial epithelium.
FIG. 2. Hematoxylin- and eosin-stained sections of marmoset uteri. A) Cross section of the apical endometrium of a nonpregnant marmoset. Note the relative lack of blood vessels and the regular appearance of the epithelium. B) Cross section of the apical implantation site of a normal embryo on Day 26 of pregnancy. The chorionic membrane (arrows) is present. ”Fingers” of syncytiotrophoblast (sy) have invaded the endometrial stroma (st). Underlying blood vessels have undergone a typical hypertrophy and proliferative response. Interstitial stromal cells are present basally (st). C) Cross section of part of the implantation site of marmoset 469W on Day 33 postovulation after receiving a parthenoge-netic embryo. Sloughed cells, possibly of placental tissue, are present in the lumen and on the apical endometrium, which has a disorganized appearance. Syncytial cells are present in the stroma. Blood vessels have collapsed (arrows). D) Cross section of the uterine epithelium of a marmoset (491W) on Day 33 postovulation after receiving a parthenogenetic embryo. Presumptive syncytiotrophoblast (sy) has invaded the stroma (st), and blood vessels have proliferated at the implantation site. Degenerative membrane is present at the luminal surface of the endometrium (arrows). A mitotic figure is present in the syncytia (arrowhead). Note the similarity to B. Bar = 50 urn.