Ferguson Virginia L, Dodson Reuben B
Department of Mechanical Engineering, University of Colorado, Boulder, CO 80309-0429, USA.
Eur J Obstet Gynecol Reprod Biol. 2009 May;144 Suppl 1:S108-13. doi: 10.1016/j.ejogrb.2009.02.024. Epub 2009 Mar 21.
The umbilical cord and its constituent tissues: an outer layer of amnion, porous Wharton's jelly, two umbilical arteries, and one umbilical vein, are designed to protect blood flow to the fetus during a term pregnancy. The outer amnion layer may regulate fluid pressure within the umbilical cord. The porous, fluid filled Wharton's jelly likely acts to prevent compression of the vessels. Blood flow is regulated by smooth muscle surrounding the arteries that is intermingled with a collagen based extracellular matrix (ECM). Doppler ultrasound measurements of blood flow within the umbilical cord, and at specific sites within the developing fetus, provide evidence of impaired blood flow in conditions such as preeclampsia. Mechanosensory communication between cells and the extracellular matrix (ECM) may likely result in cords possessing abnormal physical dimensions, impaired hemodynamics, and altered composition within the umbilical cord tissues. Few studies have explored the biomechanics of the intact umbilical cord, with its constituent tissues, from normal pregnancies or abnormal pregnancies, maternal or fetal complications. Here, alterations in the umbilical cord are reviewed concerning anatomical abnormalities, disease, or chromosomal alterations using sonography, Doppler ultrasound, histology, and biomolecular and biochemical analyses. This paper considers how current knowledge of the umbilical cord and its constituent tissues can be used to infer biomechanical function. In addition, the mechanical consequences of structural abnormalities and altered tissue structure or composition are discussed with a specific focus on preeclampsia.
外层羊膜、多孔的华通胶、两条脐动脉和一条脐静脉，旨在在足月妊娠期间保护流向胎儿的血流。外层羊膜可能调节脐带内的流体压力。充满液体的多孔华通胶可能起到防止血管受压的作用。血流由围绕动脉的平滑肌调节，这些平滑肌与基于胶原蛋白的细胞外基质（ECM）混合在一起。对脐带内以及发育中胎儿特定部位的血流进行多普勒超声测量，可提供子痫前期等病症中血流受损的证据。细胞与细胞外基质（ECM）之间的机械感觉通讯可能导致脐带具有异常的物理尺寸、受损的血液动力学以及脐带组织内成分改变。很少有研究探讨正常或异常妊娠、母体或胎儿并发症中完整脐带及其组成组织的生物力学。在此，使用超声检查、多普勒超声、组织学以及生物分子和生化分析，对脐带在解剖学异常、疾病或染色体改变方面的变化进行综述。本文考虑如何利用目前对脐带及其组成组织的认识来推断生物力学功能。此外，还讨论了结构异常以及组织结构或成分改变的机械后果，特别关注子痫前期。
