**4. Discussion**

In this study, the computational model of the human placenta and its surroundings has been developed, and the influence of the uterus contraction and elongation on the mechanical environment in the placenta was evaluated by the model. The mechanical load, such as force and stress, in the villous trees and intervillous space, which is corresponding to the placenta region in this model, would be stable although the large and various deformation could be caused by the uterus contraction. As the previous reports have indicated, the characteristic uterus contraction and elongation could deform the placenta [12, 13]. While the structural characteristics of the chorionic

*Histological Properties of the Chorionic and Basal Plates and Maintenance of the Mechanical… DOI: http://dx.doi.org/10.5772/intechopen.112935*

#### **Figure 7.**

*The first principal strain in the computational model of the human placenta and surroundings, caused by the myometrium elongation and contraction (Mode 1, Mode 2, and Mode 3 (***Table 3***)). The distribution of the strain is shown by the entire image (right), and the values along each line, indicated by* **Figure 4** *(left).*

and basal plates and its change along gestational age have been investigated [11], how these plates could influence the mechanical environment on the placenta has been barely examined. It has been reported that the smooth muscle in the marginal zone would actively influence on the uteroplacental vein [18], but its function for the blood circulation in the placenta has been barely examined.

While the thickness of the chorionic plate was just about 1% of the placental thickness [14–16, 21], the chorionic plate is composed of chorion and amnion, whose mechanical characteristics are quite different [11, 21]. Although the thickness and mechanical properties of the basal plate and marginal zone have been barely examined, these parameters in this model were the same as those of the chorionic plate in this model because they connect to the chorionic plate continuously. The results of

this computational model have shown the importance of these thin plates for maintaining the mechanical environment of the intervillous space and villous tree.

The structural characteristics of the chorionic and basal plates and marginal zone has been simplified in this model. For example, amnion could be easily separated at "spongy layer" in the chorionic plate. This behavior would be mechanically important so that this layer will be taken into the computational model in the future. Also, fibrinoid, contained a lot in the placenta, including the chorionic and basal plates, is considered in the model development. Although the mechanical properties have been barely investigated, the estimation based on the previous reports [11, 19, 20] will be helpful.
