Chapters authored
Influence of Branching Patterns and Active Contractions of the Villous Tree on Fetal and Maternal Blood Circulations in the Human Placenta
In the human placenta, fetal blood circulates in the blood vessels of the villous tree while maternal one circulates in the intervillous space, the surroundings of the villous tree. Previously, the computational model of the villous tree, whose stem villi actively contract because of the contractile cells, has been developed. The result of the computation indicated that the displacement caused by the contraction would be helpful for the fetal and maternal circulations and can be combined with the other measurements for blood circulations in the placenta. Hypoxia in the placenta is classified into the following categories: preplacental hypoxia, uteroplacental hypoxia, and postplacental hypoxia. The number and the form of the terminal villi are altered by hypoxia. Assuming that increase in the terminal villi causes a higher shear elastic modulus of the placenta, this villous tree model is useful to estimate the influence of hypoxia on the blood circulations. In this chapter, how these three types of hypoxia influence the blood circulation in the placenta by the aforementioned computational model are discussed. While preplacental hypoxia and uteroplacental hypoxia would cause similar displacement in large regions, postplacental hypoxia would do vice versa. All the types might make the fetal and maternal blood circulations difficult.
Part of the book: Highlights on Hemodynamics
Active Deformation in the Tunic of Halocynthia roretzi: How the Tissue Composed of Cellulose Responds to Stimuli and Deforms
Halocynthia roretzi, belonging to class Ascidiacea, has highly pure and crystalline cellulose Iβ, and sulfated chitin in its tunic. Cells, including hemocytes in the open circulatory system, are scattered in the tunic. The tunic, which maintains its thickness by continuous proliferation and removal, can be classified into active tissues. Recently, it has been reported that various stimuli, such as mechanical stimuli and changes in the mechanical environment, could cause active deformations of the tunic without changes in the characteristics of the tissue structure, which would be associated with influx and efflux of water. In this chapter, the system associated with active deformation, tissue structure and flux of water in the tunic is shown, with reference to the previous reports.
Part of the book: Plant Stress Physiology
Mechanical Environment in the Human Umbilical Cord and Its Contribution to the Fetal Circulation
The fetal blood flow in two arteries and one vein of the human umbilical cord could be influenced by the conditions of the fetal growth and placenta that the evaluation of the blood flow pattern by ultrasound Doppler velocimetry is important. That is, the mechanical environment in the umbilical cord should be kept to maintain the blood flow suitable for good fetus growth. In this chapter, a human umbilical cord model for finite analysis, based on the mechanical and histological characteristics is proposed. Considering that the active force production by hyaluronan, proteoglycan, smooth muscle cells, and myofibroblasts could influence the mechanical environment in the umbilical cord, the computation with the proposed model was carried out in order to evaluate the influence. The changes in the mechanical environment caused by the active force production and their influences on the fetal blood flow through the pressure rise and drop in the arteries of the umbilical cord are introduced.
Part of the book: Maternal and Child Health
Histological Properties of the Chorionic and Basal Plates and Maintenance of the Mechanical Environment in the Human Placenta
The human placenta is covered with the chorionic and basal plates, which face the fetal and maternal sides, respectively. Each plate shows its own characteristics in tissue structure so that these plates would have quite different mechanical properties: The mechanical environment of the placenta would be dependent on its position, a fetal side or maternal side. In the meantime, considering that the blood circulations in the placenta, the fetal blood flows in the blood vessels, which pass through the umbilical cord, chorionic plate, and villous trees, and the maternal blood flows in the blood vessels in the basal plate and intervillous space. The chorionic and basal plates would be necessary for the fetal and maternal blood circulations, respectively. In this chapter, the influence of the chorionic and basal plates on the mechanical environment of the placenta, and the fetal and maternal blood circulations, is explained.
Part of the book: Childbirth