Conceptus

Abstract: Background Implantation of the conceptus is a key step in pregnancy, but little is known about the time of implantation or the relation between the time of implantation and the outcome of pregnancy. Methods We collected daily urine samples for up to six months from 221 women attempting to conceive after ceasing to use contraception. Ovulation was identified on the basis of the ratio of urinary estrogen metabolites to progesterone metabolites, which changes rapidly with luteinization of the ovarian follicle. The time of implantation was defined by the appearance of chorionic gonadotropin in maternal urine. Results There were 199 conceptions, for 95 percent of which (189) we had sufficient data for analysis. Of these 189 pregnancies, 141 (75 percent) lasted at least six weeks past the last menstrual period, and the remaining 48 pregnancies (25 percent) ended in early loss. Among the pregnancies that lasted 6 weeks or more, the first appearance of chorionic gonadotropin occurred 6 to 12 days after ovulation;...

Abstract: In most species the length of a pregnancy exceeds that of the luteal phase of the ovarian cycle. The conceptus within the uterus, therefore, is believed to produce a substance or substances which directly or indirectly prolong the lifespan of the corpus luteum and prevent a return to ovarian cyclicity. This phenomenon is known as maternal recognition of pregnancy1. The active substance implicated in signalling maternal recognition of pregnancy in the sheep is an embryonic secretory protein, known as ovine trophoblast protein-1 (oTP-1) (refs 2–4), which is targeted in a paracrine manner to the uterine epithelium of the mother5. We report here the primary amino-acid sequence of oTP-1 as inferred from a cloned complementary DNA and demonstrate that the protein is most probably an interferon-alpha.

Abstract: All mammalian uteri contain endometrial glands that synthesize or transport and secrete substances essential for survival and development of the conceptus (embryo/fetus and associated extraembryonic membranes). In rodents, uterine secretory products of the endometrial glands are unequivocally required for establishment of uterine receptivity and conceptus implantation. Analyses of the ovine uterine gland knockout model support a primary role for endometrial glands and, by default, their secretions in peri-implantation conceptus survival and development. Uterine adenogenesis is the process whereby endometrial glands develop. In humans, this process begins in the fetus, continues postnatally, and is completed during puberty. In contrast, endometrial adenogenesis is primarily a postnatal event in sheep, pigs, and rodents. Typically, endometrial adenogenesis involves differentiation and budding of glandular epithelium from luminal epithelium, followed by invagination and extensive tubular coiling and branching morphogenesis throughout the uterine stroma to the myometrium. This process requires site-specific alterations in cell proliferation and extracellular matrix (ECM) remodeling as well as paracrine cell-cell and cell-ECM interactions that support the actions of specific hormones and growth factors. Studies of uterine development in neonatal ungulates implicate prolactin, estradiol-17β, and their receptors in mechanisms regulating endometrial adenogenesis. These same hormones appear to regulate endometrial gland morphogenesis in menstruating primates and humans during reconstruction of the functionalis from the basalis endometrium after menses. In sheep and pigs, extensive endometrial gland hyperplasia and hypertrophy occur during gestation, presumably to provide increasing histotrophic support for conceptus growth and development. In the rabbit, sheep, and pig, a servomechanism is proposed to regulate endometrial gland development and differentiated function during pregnancy that involves sequential actions of ovarian steroid hormones, pregnancy recognition signals, and lactogenic hormones from the pituitary or placenta. That disruption of uterine development during critical organizational periods can alter the functional capacity and embryotrophic potential of the adult uterus reinforces the importance of understanding the developmental biology of uterine glands. Unexplained high rates of peri-implantation embryonic loss in humans and livestock may reflect defects in endometrial gland morphogenesis due to genetic errors, epigenetic influences of endocrine disruptors, and pathological lesions.

Abstract: The synthesis of serum α-fetoprotein was studied in 16 human embryos and fetuses between 4.2 and 18 weeks of gestation by incubation of selected tissues in 14C-labeled amino acids followed by immunoelectrophoresis of the culture fluids and radioautography. Relatively large amounts of radioactive α-fetoprotein were found in each of the liver cultures and in cultures of the developing yolk sac. Smaller amounts of labeled α-fetoprotein were observed in almost all of the gastrointestinal tract cultures. Labeled α-fetoprotein was formed in the kidney cultures from 1 of 9 conceptuses and in only 1 of 14 placentas cultured. None of the cultures of lung, thymus, pancreas, skeletal muscle, amnion, chorion, or blood produced detectable amounts of α-fetoprotein.