Trophoblast cells of the placenta are established at the blastocyst stage and differentiate into specialized subtypes after implantation. In mice, the outer layer of the placenta consists of trophoblast giant cells that invade the uterus and promote maternal blood flow to the implantation site by producing cytokines with angiogenic and vasodilatory actions. The innermost layer, called the labyrinth, consists of branched villi that provide a large surface area for nutrient transport and are composed of trophoblast cells and underlying mesodermal cells derived from the allantois. The chorioallantoic villi develop after embryonic day (E) 8.5 through extensive folding and branching of an initially flat sheet of trophoblast cells, the chorionic plate, in response to contact with the allantois. We show here that Gcm1, encoding the transcription factor glial cells missing-1 (Gcm1), is expressed in small clusters of chorionic trophoblast cells at the flat chorionic plate stage and at sites of chorioallantoic folding and extension when morphogenesis begins. Mutation of Gcm1 in mice causes a complete block to branching of the chorioallantoic interface, resulting in embryonic mortality by E10 due to the absence of the placental labyrinth. In addition, chorionic trophoblast cells in Gcm1-deficient placentas do not fuse to form syncytiotrophoblast. Abnormal development of placental villi is frequently associated with fetal death and intrauterine growth restriction in humans, and our studies provide the earliest molecular insight into this aspect of placental development.

Improvement of ovarian cancer patient outcome requires well-characterized animal models in which to evaluate novel therapeutics. Xenograft models are frequently used, but with little discussion of disease histology. The objectives of this study were to inject 11 ovarian cancer cell lines intraperitoneally (ip), and a subset intrabursally (ib; orthotopic), into nude mice and to analyze the resulting pathologies. Eight of 11 lines injected ip formed tumors within 3 months at variable rates with the following histological subtype distribution: one endometrioid, one serous, one clear cell, and five undifferentiated. Only mice injected with A2780-cp cells presented with ovarian-specific metastases (11 of 88), and the survival time of these animals was significantly shorter, which may be attributed to the higher proliferation rate as determined by Ki67 positivity. Additional analysis of the influence of the ovarian microenvironment on cell characteristics was conducted with ib injection of two cell lines (OVCA 429 and ES-2). The site of injection did not affect the tumor histology, the effect on proliferation was cell-type dependent, and the tumor take rate (cell survival) was negatively affected for OVCA 429 cells. The animal models described herein represent histologically distinct models of both early and late stage ovarian cancer useful for evaluation of therapeutics.

Mouse embryo development is identically inhibited by raised osmolarity, whether produced by added NaCl or raffinose, demonstrating that high osmolarity is itself detrimental to embryos. In the face of increased osmolarity, cells in the brain and kidney, and likely many other cells, accumulate nonperturbing organic osmolytes in their cytoplasm. In the presence of any of a number of organic compounds that were proven or probable substrates of either the Gly or the beta transport systems, mouse embryo development in vitro was protected from raised osmolarity. Zygotes developed past the "2-cell block," and with most Gly or beta substrates, to the blastocyst stage. The most effective osmoprotectants were glycine, glutamine, betaine, proline, beta-alanine, and hypotaurine; several others were partially effective. A model Gly substrate, glycine, was effective at a much lower concentration (EC50 = 50 microM) than was a model beta substrate, beta-alanine (EC50 = 1.3 mM). The protective effect of these two compounds was additive, indicating a common mode of action. The various effective compounds tested do not all share metabolic pathways or other such properties in common. Thus, it is likely that cleavage-stage mouse embryos utilize them, in large part, as organic osmolytes.

Mouse zygotes and early cleavage-stage embryos are sensitive to increased osmolarity. However, development can occur at higher osmolarities if any of a number of organic compounds are present. One of the most effective of these is glycine. We have found that the amount of glycine accumulated by embryos during in vitro culture from the zygote to two-cell stage depends on the osmolarity of the medium, with significantly more glycine accumulated at 310 or 340 mOsM than at 250 mOsM. The accumulated glycine is largely retained in a freely diffusible form, as it can be released via a swelling-activated pathway in two-cell embryos. Increased glycine accumulation does not seem to depend on an increase in its rate of transport. The transport rate is not higher in two-cell embryos that have been cultured from zygotes in hypertonic vs. normal medium, and hypertonicity only slightly stimulates transport in zygotes. Our results indicate that glycine functions as an organic osmolyte in early mouse embryos.