In primates, the most important signal yet described for the maternal recognition of pregnancy is CG. Marmosets passively or actively immunized against human CG p-subunit during the first 6 wk of gestation lose their pregnancies. Therefore, hormone profiles shown here for recipients of parthenogenetic embryos were interesting because both progesterone and ir-inhibin, produced by the CL in marmosets, were maintained at levels that would be associated with continued luteotropic support. ampicillin antibiotic
However, CG, the major luteotropin provided by the embryo, remained at nonpregnant levels in the peripheral plasma. Despite these low levels of CG, parthenogenetic embryos did implant, as determined histologically. Marmoset partheno-genones may have produced enough CG to reach the ovary and cause a luteotropic effect, but CG was not produced in quantities sufficient to be measured in the peripheral circulation. Webley et al. have shown that marmoset luteal cells in vivo are exposed to an unknown luteotropin 2 days after implantation, before CG can be measured in the maternal plasma.