title: Uterine glands provide histiotrophic nutrition for the human fetus during the first trimester of pregnancy.
abstract: Providing adequate nutrition to the fetus is key to a successful pregnancy. The interstitial form of implantation displayed by the human blastocyst is generally associated with early onset of maternal blood flow to the developing placenta, and hence hemotrophic exchange. However, the recent finding that the maternal intraplacental circulation is not fully established until the third month of gestation suggests that human fetal nutrition may be initially histiotrophic. We therefore investigated activity of the uterine glands during early pregnancy. We demonstrate here that these glands remain active until at least wk 10 of pregnancy, and that their secretions are delivered freely into the placental intervillous space. We also demonstrate phagocytic uptake by the placental syncytiotrophoblast of two glycoproteins, the mucin MUC-1 and glycodelin A, synthesized in the maternal glands. Glycodelin was also detected within the epithelium of the secondary yolk sac lining the exocoelomic cavity, indicating that the yolk sac may play an important role in nutrient exchange before vascularisation of the chorionic villi. Our findings demonstrate that the uterine glands are an important source of nutrients during organogenesis, when metabolism is essentially anaerobic.
authors.affiliation: Department of Anatomy, University of Cambridge, Downing Street, Cambridge CB2 3DY, United Kingdom. gjb2@cam.ac.uk
authors.forename: Graham J
authors.initials: GJ
authors.lastname: Burton
authors.forename: Adrian L
authors.initials: AL
authors.lastname: Watson
authors.forename: Joanne
authors.initials: J
authors.lastname: Hempstock
authors.forename: Jeremy N
authors.initials: JN
authors.lastname: Skepper
authors.forename: Eric
authors.initials: E
authors.lastname: Jauniaux
mesh_terms: D004703:Endocrine System / Q000378:metabolism*; D005260:Female; D005333:Fetus / Q000502:physiology*; D000071816:Glycodelin; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D008854:Microscopy, Electron; D018396:Mucin-1 / Q000378:metabolism; D009747:Nutritional Physiological Phenomena / Q000502:physiology*; D011247:Pregnancy / Q000502:physiology*; D011257:Pregnancy Proteins / Q000378:metabolism; D011261:Pregnancy Trimester, First; D014599:Uterus / Q000378:metabolism* / Q000648:ultrastructure; D015017:Yolk Sac / Q000378:metabolism
chemical_list: D000071816:Glycodelin; D006023:Glycoproteins; D018396:Mucin-1; C045246:PAEP protein, human; D011257:Pregnancy Proteins