Studies of calcium transfer across the placenta have been reviewed because of the physiological and nutritional importance of this mineral during pregnancy, especially in order to better understand its contribution to...Studies of calcium transfer across the placenta have been reviewed because of the physiological and nutritional importance of this mineral during pregnancy, especially in order to better understand its contribution to development of the fetal skeleton. The placental transfer of maternal calcium to the fetus represents a vital mechanism for fetal development and breast-milk production, yet little meaningful information is currently available regarding the biochemical mechanisms involved in this process. Once again, the use of different animal models as rodents, rabbit, sheep and bovine have demonstrate different mechanisms of calcium transport across the placenta and contribute to better understand its effects in both fetus and mother during the gestation. In relation to the transfer of calcium from the mother to fetus data suggest it occur via an active mechanism;thus calcium concentration is higher in fetus than in maternal blood. Despite conflicting reports, several investigators agreed that calcium concentration in the fetal blood is mainly regulated by fetal parathyroid hormone and plasma concentration of vitamin D3, a metabolite that plays a key role in calcium transport through the syncytial cells.展开更多
Many studies have reported on the different types of placenta in different species, but accessory or paraplacental structures are mentioned only in species that have such a nutrient-exchanging mechanism. Hystricomorph...Many studies have reported on the different types of placenta in different species, but accessory or paraplacental structures are mentioned only in species that have such a nutrient-exchanging mechanism. Hystricomorph rodents possess a subplacenta, swine and equines have the placental areola, equines have the chorionic girdle, and carnivores have hemophagous organs that are equivalent to the placental hematoma in ruminants. These accessory structures are specialized tissues for specific nutrient exchanges in different species, and they are adaptive modifications exhibited by domestic and wild species to remedy the nutritional deficiencies that are related to permeability of the main placenta to important nutrients for the growth and development of the fetus during the gestation.展开更多
Maternal immunity is the main early defense against infectious agents in newborns. Immunoglobulin G (IgG) is indispensable for immune defense against infectious agents. IgG is transported through either the colostrum ...Maternal immunity is the main early defense against infectious agents in newborns. Immunoglobulin G (IgG) is indispensable for immune defense against infectious agents. IgG is transported through either the colostrum or the placenta. Immunoglobulins are antibodies, and the five different classes of these antibodies are IgG, IgA, IgM, IgD and IgE. Through their biological function of binding antigens, antibodies facilitate the removal of antigens from the body. The placenta is a temporary maternal-fetal organ, whose principal function is to allow the controlled exchange of metabolites between mother and embryo/fetus during gestation. The placenta types in different species are classified by the number of membranes separating the maternal and fetal blood circulation. Humans, lagomorphs and rodents have hemochorial placentas, which require a receptor for IgG transfer. In other animals, such as horse and pig (epitheliochorial placenta), ruminants (synepitheliochorial placenta) and carnivores (endotheliochorial placenta), antibodies are transferred via the colostrum and absorbed by passive diffusion. This review covers immunoglobulin transport in several types of placentas.展开更多
The homeostasis is maintained by the immune system which is constituted a network of organs, cells and molecules that act to combating the assaults affecting the body. The immune function has been conceptually divided...The homeostasis is maintained by the immune system which is constituted a network of organs, cells and molecules that act to combating the assaults affecting the body. The immune function has been conceptually divided into innate immunity and acquired immunity. Among the effector cells of innate immunity are the natural killer cells (NK), they play an important role in the reproductive immunology in the establishment and maintenance of pregnancy and fetus. The study of the biological mechanisms involved in the maintenance of pregnancy contributes to increase knowledge about immune tolerance. The way in which the immune system is modulated, and the study of the recognition systems maternal innate and adaptive occurring during pregnancy, allow to understand the survival of the fetus. The aim of this review was to present the main functions of NK cells and describe their role in the process of trophoblastic invasion in the deployment process, in the maternal-fetal interaction and development of the fetus. The knowledge of the precise role of NK cells is necessary, because these cells may be responsible for reactions which lead to embryonic and fetal loss during the organogenesis process.展开更多
Recently the fetal membranes are regarded to be abundant, ethically acceptable and easily accessible sources of mesenchymal stem cells, which cause only minor immunogenic troubles. In addition, these membranes have be...Recently the fetal membranes are regarded to be abundant, ethically acceptable and easily accessible sources of mesenchymal stem cells, which cause only minor immunogenic troubles. In addition, these membranes have been studied as an alternative to adult and embryonic stem cells. The chorion develops firstly as a layer of simple avascular epithelium (trophoblast). The amnion, as the chorion is also an avascular membrane. It is derived from the ectoderm, and forms a very thin membrane which surrounded the embryo in development. The hypoblast and exocoelomic membrane together originates the yolk sac which late will give rise to the allantois. The study of the origin and development of these tissues is of vital importance for obtaining stem cells. Different cell lineages can be obtained from the fetal placental tissues: the hematopoietic lineage is found in the chorion, allantois and, yolk sac, and the mesenchymal lineage is found in the chorion and amnion. The properties and potential for differentiation of fetal stem cells isolated from placental tissues must be characterized in order for them to be used in the treatment of several diseases. The chorion, yolk sac, allantois, and amnion contain heterogeneous cell populations. However, few studies have focused on characterizing these alternative stem cells sources. The amnion has a significant advantage over the other fetal membranes, mainly due to its easily accessibility for collection in humans and rodents and also because it contains populations of pluripotent and multipotent cells. In some other species (dogs, ruminants, horses, cats, and swine) the allantoic fluid is more easily accessible, but there is little information regarding the characterization of the cell population. This review will address advances in the isolation of stem cells from fetal placental tissues and describe their characterization and possible use in cell therapy, as well as their origin and development.展开更多
文摘Studies of calcium transfer across the placenta have been reviewed because of the physiological and nutritional importance of this mineral during pregnancy, especially in order to better understand its contribution to development of the fetal skeleton. The placental transfer of maternal calcium to the fetus represents a vital mechanism for fetal development and breast-milk production, yet little meaningful information is currently available regarding the biochemical mechanisms involved in this process. Once again, the use of different animal models as rodents, rabbit, sheep and bovine have demonstrate different mechanisms of calcium transport across the placenta and contribute to better understand its effects in both fetus and mother during the gestation. In relation to the transfer of calcium from the mother to fetus data suggest it occur via an active mechanism;thus calcium concentration is higher in fetus than in maternal blood. Despite conflicting reports, several investigators agreed that calcium concentration in the fetal blood is mainly regulated by fetal parathyroid hormone and plasma concentration of vitamin D3, a metabolite that plays a key role in calcium transport through the syncytial cells.
文摘Many studies have reported on the different types of placenta in different species, but accessory or paraplacental structures are mentioned only in species that have such a nutrient-exchanging mechanism. Hystricomorph rodents possess a subplacenta, swine and equines have the placental areola, equines have the chorionic girdle, and carnivores have hemophagous organs that are equivalent to the placental hematoma in ruminants. These accessory structures are specialized tissues for specific nutrient exchanges in different species, and they are adaptive modifications exhibited by domestic and wild species to remedy the nutritional deficiencies that are related to permeability of the main placenta to important nutrients for the growth and development of the fetus during the gestation.
文摘Maternal immunity is the main early defense against infectious agents in newborns. Immunoglobulin G (IgG) is indispensable for immune defense against infectious agents. IgG is transported through either the colostrum or the placenta. Immunoglobulins are antibodies, and the five different classes of these antibodies are IgG, IgA, IgM, IgD and IgE. Through their biological function of binding antigens, antibodies facilitate the removal of antigens from the body. The placenta is a temporary maternal-fetal organ, whose principal function is to allow the controlled exchange of metabolites between mother and embryo/fetus during gestation. The placenta types in different species are classified by the number of membranes separating the maternal and fetal blood circulation. Humans, lagomorphs and rodents have hemochorial placentas, which require a receptor for IgG transfer. In other animals, such as horse and pig (epitheliochorial placenta), ruminants (synepitheliochorial placenta) and carnivores (endotheliochorial placenta), antibodies are transferred via the colostrum and absorbed by passive diffusion. This review covers immunoglobulin transport in several types of placentas.
文摘The homeostasis is maintained by the immune system which is constituted a network of organs, cells and molecules that act to combating the assaults affecting the body. The immune function has been conceptually divided into innate immunity and acquired immunity. Among the effector cells of innate immunity are the natural killer cells (NK), they play an important role in the reproductive immunology in the establishment and maintenance of pregnancy and fetus. The study of the biological mechanisms involved in the maintenance of pregnancy contributes to increase knowledge about immune tolerance. The way in which the immune system is modulated, and the study of the recognition systems maternal innate and adaptive occurring during pregnancy, allow to understand the survival of the fetus. The aim of this review was to present the main functions of NK cells and describe their role in the process of trophoblastic invasion in the deployment process, in the maternal-fetal interaction and development of the fetus. The knowledge of the precise role of NK cells is necessary, because these cells may be responsible for reactions which lead to embryonic and fetal loss during the organogenesis process.
基金the several members of the Faculty of Veterinary Medicine and Animal Science,University of Sao Paulo,Brazil and also the Fundacao de Amparo a Pesquisa do Estado de Sao Paulo—Fapesp for financial support.
文摘Recently the fetal membranes are regarded to be abundant, ethically acceptable and easily accessible sources of mesenchymal stem cells, which cause only minor immunogenic troubles. In addition, these membranes have been studied as an alternative to adult and embryonic stem cells. The chorion develops firstly as a layer of simple avascular epithelium (trophoblast). The amnion, as the chorion is also an avascular membrane. It is derived from the ectoderm, and forms a very thin membrane which surrounded the embryo in development. The hypoblast and exocoelomic membrane together originates the yolk sac which late will give rise to the allantois. The study of the origin and development of these tissues is of vital importance for obtaining stem cells. Different cell lineages can be obtained from the fetal placental tissues: the hematopoietic lineage is found in the chorion, allantois and, yolk sac, and the mesenchymal lineage is found in the chorion and amnion. The properties and potential for differentiation of fetal stem cells isolated from placental tissues must be characterized in order for them to be used in the treatment of several diseases. The chorion, yolk sac, allantois, and amnion contain heterogeneous cell populations. However, few studies have focused on characterizing these alternative stem cells sources. The amnion has a significant advantage over the other fetal membranes, mainly due to its easily accessibility for collection in humans and rodents and also because it contains populations of pluripotent and multipotent cells. In some other species (dogs, ruminants, horses, cats, and swine) the allantoic fluid is more easily accessible, but there is little information regarding the characterization of the cell population. This review will address advances in the isolation of stem cells from fetal placental tissues and describe their characterization and possible use in cell therapy, as well as their origin and development.
