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The placenta is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient, gas and waste exchange between the physically separate maternal and fetal circulations, and is an important endocrine organ, producing hormones that regulate both maternal and fetal physiology during pregnancy. The placenta connects to the fetus via the umbilical cord, and on the opposite aspect to the maternal uterus in a species-dependent manner. In humans, a thin layer of maternal decidual (endometrial) tissue comes away with the placenta when it is expelled from the uterus following birth. Placentas are a defining characteristic of placental mammals, but are also found in marsupials and some non-mammals with varying levels of development.
Intrauterine growth restriction (IUGR), or fetal growth restriction, is the poor growth of a fetus while in the womb during pregnancy. IUGR is defined by clinical features of malnutrition and evidence of reduced growth regardless of an infant's birth weight percentile. The causes of IUGR are broad and may involve maternal, fetal, or placental complications.
Prolactin (PRL), also known as lactotropin and mammotropin, is a protein best known for its role in enabling mammals to produce milk. It is influential in over 300 separate processes in various vertebrates, including humans. Prolactin is secreted from the pituitary gland in response to eating, mating, estrogen treatment, ovulation and nursing. It is secreted heavily in pulses in between these events. Prolactin plays an essential role in metabolism, regulation of the immune system and pancreatic development.
Gestational hypertension or pregnancy-induced hypertension (PIH) is the development of new hypertension in a pregnant woman after 20 weeks' gestation without the presence of protein in the urine or other signs of pre-eclampsia. Gestational hypertension is defined as having a blood pressure greater than 140/90 on two occasions at least 6 hours apart.
Complications of pregnancy are health problems that are related to, or arise during pregnancy. Complications that occur primarily during childbirth are termed obstetric labor complications, and problems that occur primarily after childbirth are termed puerperal disorders. While some complications improve or are fully resolved after pregnancy, some may lead to lasting effects, morbidity, or in the most severe cases, maternal or fetal mortality.
Lactiferous ducts are ducts that converge and form a branched system connecting the nipple to the lobules of the mammary gland. When lactogenesis occurs, under the influence of hormones, the milk is moved to the nipple by the action of smooth muscle contractions along the ductal system to the tip of the nipple. They are also referred to as galactophores, galactophorous ducts, mammary ducts, mamillary ducts or milk ducts.
The prolactin receptor (PRLR) is a type I cytokine receptor encoded in humans by the PRLR gene on chromosome 5p13-14. It is the receptor for prolactin (PRL). The PRLR can also bind to and be activated by growth hormone (GH) and human placental lactogen (hPL). The PRLR is expressed in the mammary glands, pituitary gland, and other tissues. It plays an important role in lobuloalveolar development of the mammary glands during pregnancy and in lactation.
Human placental lactogen (hPL), also called human chorionic somatomammotropin (hCS) or human chorionic somatotropin, is a polypeptide placental hormone, the human form of placental lactogen. Its structure and function are similar to those of human growth hormone. It modifies the metabolic state of the mother during pregnancy to facilitate energy supply to the fetus. hPL has anti-insulin properties. hPL is a hormone secreted by the syncytiotrophoblast during pregnancy. Like human growth hormone, hPL is encoded by genes on chromosome 17q22-24. It was identified in 1963.
Placental insufficiency or utero-placental insufficiency is the failure of the placenta to deliver sufficient nutrients to the fetus during pregnancy, and is often a result of insufficient blood flow to the placenta. The term is also sometimes used to designate late decelerations of fetal heart rate as measured by cardiotocography or an NST, even if there is no other evidence of reduced blood flow to the placenta, normal uterine blood flow rate being 600mL/min.
Decidualization is a process that results in significant changes to cells of the endometrium in preparation for, and during, pregnancy. This includes morphological and functional changes to endometrial stromal cells (ESCs), the presence of decidual white blood cells (leukocytes), and vascular changes to maternal arteries. The sum of these changes results in the endometrium changing into a structure called the decidua. In humans, the decidua is shed during childbirth.
Neurokinin B (NKB) belongs in the family of tachykinin peptides. Neurokinin B is implicated in a variety of human functions and pathways such as the secretion of gonadotropin-releasing hormone. Additionally, NKB is associated with pregnancy in females and maturation in young adults. Reproductive function is highly dependent on levels of both neurokinin B and also the G-protein coupled receptor ligand kisspeptin. The first NKB studies done attempted to resolve why high levels of the peptide may be implicated in pre-eclampsia during pregnancy. NKB, kisspeptin, and dynorphin together are found in the arcuate nucleus (ARC) known as the KNDy subpopulation. This subpopulation is targeted by many steroid hormones and works to form a network that feeds back to GnRH pulse generator.
Metabolic imprinting refers to the long-term physiological and metabolic effects that an offspring's prenatal and postnatal environments have on them. Perinatal nutrition has been identified as a significant factor in determining an offspring's likelihood of it being predisposed to developing cardiovascular disease, obesity, and type 2 diabetes amongst other conditions.
Growth hormone 2 (GH2), also known more commonly as placental growth hormone (PGH) or growth hormone variant (GH-V), is a protein that in humans is encoded by the GH2 gene. It is produced by and secreted from the placenta during pregnancy, and becomes the predominant form of growth hormone (GH) in the body during this time. Its cogener is growth hormone 1 (GH1), or pituitary growth hormone.
The Somatotropin family is a protein family whose titular representative is somatotropin, also known as growth hormone, a hormone that plays an important role in growth control. Other members include choriomammotropin (lactogen), its placental analogue; prolactin, which promotes lactation in the mammary gland, and placental prolactin-related proteins; proliferin and proliferin related protein; and somatolactin from various fishes. The 3D structure of bovine somatotropin has been predicted using a combination of heuristics and energy minimisation.
Uterine serpins are members of the A clade of the serine protease inhibitor (serpin) superfamily of proteins and are encoded by the SERPINA14 gene. Uterine serpins are produced by the endometrium of a restricted group of mammals under the influence of progesterone or estrogen. These proteins appear to be inactive protease inhibitors and may function during pregnancy to regulate immune function or participate in transplacental transport.
Retinol-binding proteins (RBP) are a family of proteins with diverse functions. They are carrier proteins that bind retinol. Assessment of retinol-binding protein is used to determine visceral protein mass in health-related nutritional studies.
Maternal fetal stress transfer is a physiological phenomenon in which psychosocial stress experienced by a mother during her pregnancy can be transferred to the fetus. Psychosocial stress describes the brain's physiological response to perceived social threat. Because of a link in blood supply between a mother and fetus, it has been found that stress can leave lasting effects on a developing fetus, even before a child is born. According to recent studies, these effects are mainly the result of two particular stress biomarkers circulating in the maternal blood supply: cortisol and catecholamines.
The multigenic complex formed by the human growth hormone (hGH) and the human placental lactogen (hPL) takes part in the process of maternal and fetal metabolism regulation and the following growth and development of the fetus.
Delayed onset of lactation (DOL) describes the absence of copious milk secretion (onset of lactation) within the first 72 hours following childbirth. It affects around 20–40% of lactating women, the prevalence differs among distinct populations.
Hormones during pregnancy are the result of an intricate interaction between hormones generated by different glands and organs. The primary hormones involved comprise human chorionic gonadotropin (hCG), progesterone, estrogen, human placental lactogen (hPL), and oxytocin. Hormones are synthesized in certain organs, including the ovaries, placenta, and pituitary gland. These hormones have essential functions in pregnancy test, maintaining the uterine lining, fetal development, preventing premature labor, and the initiation and support of labor.
References
- ↑ Limesand, Sean W.; Anthony, Russell V. (2001-04-15). "Novel activator protein-2α splice-variants function as transactivators of the ovine placental lactogen gene". European Journal of Biochemistry. 268 (8): 2390–2401. doi:10.1046/j.1432-1327.2001.02124.x. ISSN 0014-2956. PMID 11298758.
- 1 2 3 Takahashi, Toru (February 2006). "Biology of the prolactin family in bovine placenta. I. Bovine placental lactogen: Expression, structure and proposed roles". Animal Science Journal. 77 (1): 10–17. doi:10.1111/j.1740-0929.2006.00314.x. ISSN 1344-3941.
- 1 2 Shiota, Kunio; Hirosawa, Mitsuko; Hattori, Naka; Itonori, Saki; Miura, Ryuich; Noda, Ken; Takahashi, Michio; Ogawa, Tomoya (1994). "Structural and Functional Aspects of Placental Lactogens (PLs) and Ovarian 20α-Hydroxysteroid Dehydrogenase (20α-HSD) in the Rat". Endocrine Journal. 41 (Supplement): S43 –S56. doi:10.1507/endocrj.41.Supplement_S43. ISSN 0918-8959.
- ↑ Simmons, David G; Rawn, Saara; Davies, Alastair; Hughes, Martha; Cross, James C (December 2008). "Spatial and temporal expression of the 23 murine Prolactin/Placental Lactogen-related genes is not associated with their position in the locus". BMC Genomics. 9 (1): 352. doi: 10.1186/1471-2164-9-352 . ISSN 1471-2164. PMC 2527339 . PMID 18662396.
- ↑ Braun, Thorsten; Meng, Wenbin; Shang, Hongkai; Li, Shaofu; Sloboda, Deborah M.; Ehrlich, Loreen; Lange, Karolin; Xu, Huaisheng; Henrich, Wolfgang; Dudenhausen, Joachim W.; Plagemann, Andreas; Newnham, John P.; Challis, John R. G. (January 2015). "Early Dexamethasone Treatment Induces Placental Apoptosis in Sheep". Reproductive Sciences. 22 (1): 47–59. doi:10.1177/1933719114542028. ISSN 1933-7191. PMC 4275451 . PMID 25063551.