Objective Analysis of Vaginal Ultrasound Video Clips for Exploring Uterine Peristalsis Post Vaginal and Cesarean Section Deliveries

Biomechanics of Early Life in the Female Reproductive Tract

Early human life that starts at the onset of fertilization and ends with implantation of the embryo in the uterine wall is the foundation for a successful pregnancy. The different stages during this period require biomechanical mechanisms, which are mostly unknown due to difficulties to conduct in vivo studies in humans.

Quantitative imaging of tongue kinematics during infant feeding and adult swallowing reveals highly conserved patterns

Tongue motility is an essential physiological component of human feeding from infancy through adulthood. At present, it is a challenge to distinguish among the many pathologies of swallowing due to the absence of quantitative tools. We objectively quantified tongue kinematics from ultrasound imaging during infant and adult feeding. The functional advantage of this method is presented in several subjects with swallowing difficulties. We demonstrated for the first time the differences in tongue kinematics during breast- and bottle-feeding, showing the arrhythmic sucking pattern during bottle-feeding as compared with breastfeeding in the same infant with torticollis. The method clearly displayed the improvement of tongue motility after frenotomy in infants with either tongue-tie or restrictive labial frenulum. The analysis also revealed the absence of posterior tongue peristalsis required for safe swallowing in an infant with dysphagia. We also analyzed for the first time the tongue kinematics in an adult during water bolus swallowing demonstrating tongue peristaltic-like movements in both anterior and posterior segments. First, the anterior segment undulates to close off the oral cavity and the posterior segment held the bolus, and then, the posterior tongue propelled the bolus to the pharynx. The present methodology of quantitative imaging revealed highly conserved patterns of tongue kinematics that can differentiate between swallowing pathologies and evaluate treatment interventions. The method is novel and objective and has the potential to advance knowledge about the normal swallowing and management of feeding disorders.

Tissue engineered endometrial barrier exposed to peristaltic flow shear stresses

Cyclic myometrial contractions of the non-pregnant uterus induce intra-uterine peristaltic flows, which have important roles in transport of sperm and embryos during early stages of reproduction. Hyperperistalsis in young females may lead to migration of endometrial cells and development of adenomyosis or endometriosis. We conducted an in vitro study of the biological response of a tissue engineered endometrial barrier exposed to peristaltic wall shear stresses (PWSSs). The endometrial barrier model was co-cultured of endometrial epithelial cells on top of myometrial smooth muscle cells (MSMCs) in custom-designed wells that can be disassembled for mechanobiology experiments. A new experimental setup was developed for exposing the uterine wall in vitro model to PWSSs that mimic the in vivo intra-uterine environment. Peristaltic flow was induced by moving a belt with bulges to deform the elastic cover of a fluid filled chamber that held the uterine wall model at the bottom. The in vitro biological model was exposed to peristaltic flows for 60 and 120 min and then stained for immunofluorescence studies of alternations in the cytoskeleton. Quantification of the F-actin mass in both layers revealed a significant increase with the length of exposure to PWSSs. Moreover, the inner layer of MSMCs that were not in direct contact with the fluid also responded with an increase in the F-actin mass. This new experimental approach can be expanded to in vitro studies of multiple structural changes and genetic expressions, while the tissue engineered uterine wall models are tested under conditions that mimic the in vivo physiological environment.

Analysis of in vivo uterine peristalsis in the non-pregnant female mouse

Uterine peristalsis due to spontaneous contractions of the myometrial smooth muscles has important roles in pre-implantation processes of intra-uterine sperm transport to the fertilization site, and then embryo transport to the implantation sites. We developed a new objective methodology to study in vivo uterine peristalsis in female mice during the pro-oestrus phase. The acquisition procedure of the uterine organ is remote without interfering with the organ function. The uniqueness of the new approach is that video images of physiological pattern were converted using image processing and new algorithms to biological time-dependent signals that can be processed with existing algorithms for signal processing. Using this methodology we found that uterine peristalsis in the pro-oestrus mouse is in the range of 0.008-0.029 Hz, which is about one contraction per minute and with fairly symmetric contractions that occasionally propagate caudally. This rate of contractions is similar to that of human uterine peristalsis acquired in vivo, which is important information for a popular animal model.

Biomechanics of the human uterus

The appropriate biomechanical function of the uterus is required for the execution of human reproduction. These functions range from aiding the transport of the embryo to the implantation site, to remodeling its tissue walls to host the placenta, to protecting the fetus during gestation, to contracting forcefully for a safe parturition and postpartum, to remodeling back to its nonpregnant condition to renew the cycle of menstruation. To serve these remarkably diverse functions, the uterus is optimally geared with evolving and contractile muscle and tissue layers that are cued by chemical, hormonal, electrical, and mechanical signals. The relationship between these highly active biological signaling mechanisms and uterine biomechanical function is not completely understood for normal reproductive processes and pathological conditions such as adenomyosis, endometriosis, infertility and preterm labor. Animal studies have illuminated the rich structural function of the uterus, particularly in pregnancy. In humans, medical imaging techniques in ultrasound and magnetic resonance have been combined with computational engineering techniques to characterize the uterus in vivo, and advanced experimental techniques have explored uterine function using ex vivo tissue samples. The collective evidence presented in this review gives an overall perspective on uterine biomechanics related to both its nonpregnant and pregnant function, highlighting open research topics in the field. Additionally, uterine disease and infertility are discussed in the context of tissue injury and repair processes and the role of computational modeling in uncovering etiologies of disease. WIREs Syst Biol Med 2017, 9:e1388. doi: 10.1002/wsbm.1388 For further resources related to this article, please visit the WIREs website.