Stretching of fetal membranes increases the concentration of interleukin-8 and collagenase activity☆,☆☆,★
Section snippets
MATERIAL AND METHODS
This research was approved by the research committee of Hamamatsu University. Written consent was obtained from all patients involved in this study.
A muscle biopsy specimen was collected from the lower uterine segment during elective cesarean sections and before any clinical signs of labor (n = 15). Cesarean sections were done because of previous cesarean sections (n = 10) or primigravid women with breech presentations (n = 5). All cases were between 38 and 40 weeks' of gestation. Multiple
RESULTS
Amnion, whole fetal membranes, and muscle strips from the lower uterine segment increased in length in response to stretching for 4 hours. Fig. 2 shows the percent increase in length of stretched biopsy specimens in response to traction in grams. Amnion has a remarkable ability for stretching, compared with whole fetal membranes.
High concentrations of IL-8 were found in control whole
COMMENT
Fetal membranes do not line the uterine cavity passively, but they are in a state of continuous stretching and tension during pregnancy. The maximum stretching and tension are reached at term, and more stretching will occur with the start of uterine contractions.3 It was found that amnion can be stretched more than the whole fetal membranes. This observation is similar to normal cervical dilatation where the chorion, usually torn earlier, and the amnion will form the bag of forewater.
Mechanical
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Progesterone control of myometrial contractility
2023, Journal of Steroid Biochemistry and Molecular BiologyReprint of: Myometrial activation: Novel concepts underlying labor
2020, PlacentaCitation Excerpt :They are comprised of two tissue layers: the inner amnion, a single layer of cuboidal epithelial cells, and the outer chorion, that is in direct contact with the maternal decidua. During the 3rd trimester of pregnancy, the fetal membranes respond to mechanical stretching by secreting pro-inflammatory cytokines (such as Interleukin (IL)-6, CXCL8/IL-8) and activation of prostaglandin (PG)-synthesizing enzymes (cyclooxygenase(COX) 1/2), resulting in membrane activation and rupture [13–16]. It has also been proposed that the senescence of the fetal membranes triggers activation of the adjacent decidua through the release of damage-associated molecular patterns molecules (DAMPs/alarmins) that increase non-infectious inflammatory immune response [17].
Myometrial activation: Novel concepts underlying labor
2020, PlacentaRecurrence risk of preterm birth in a subsequent singleton pregnancy after a spontaneous preterm triplet delivery
2020, European Journal of Obstetrics and Gynecology and Reproductive BiologyCitation Excerpt :The rate of preterm delivery among multifetal gestations is substantial. This higher risk for preterm delivery is at least partially explained by uterine over- distension, a condition which has been shown to elicit inflammatory changes including increased production of prostaglandins and collagenase activity, leading to premature cervical ripening [15–17]. In addition, the static load upon the cervix during multifetal pregnancy, caused by the intrauterine pressure and the tensile stresses from the uterine walls, has also been suggested as a potential mechanism for PTB, leading to cervical shortening in the absence of uterine contractions [18].
Preterm Labor and Birth
2016, Obstetrics: Normal and Problem Pregnancies
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From the Department of Obstetrics and Gynecology, Hamamatsu University School of Medicine.
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Reprint requests: Emad El Maradny, Department of Obstetrics and Gynecology, Hamamatsu University School of Medicine, 3600 Handa-cho, 431-31 Hamamatsu, Japan.
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