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Initiation of Labor in Women
Published in Gabor Huszar, The Physiology and Biochemistry of the Uterus in Pregnancy and Labor, 2020
M. Linette Casey, Paul C. MacDonald
Anatomically, the amnion is poised ideally to receive and to transmit a fetal signal. This innermost fetal membrane is bathed by the amniotic fluid and is contiguous with the chorion laeve, also a very thin membrane of fetal origin, which, in turn, is contiguous with the maternal decidua vera. Direct communication between the fetus and amnion is established by way of the amniotic fluid that, at term, is comprised principally of fetal secretions from kidney (fetal urine), lung, and skin. At term, the fetal membranes occupy a large (0.6 m2) surface area in the uterine cavity. Thus, the fetus is in communication with its mother by way of the large surface area that is provided by the fetal membranes. Moreover, it would seem to be advantageous for prostaglandin formation to be initiated at a site removed from the placental implantation site, since these compounds are potent vasoconstrictive agents and, thereby, could lead to abruption of the placenta.
Characterization Of Fluids And Gases
Published in Sujoy K. Guba, Bioengineering in Reproductive Medicine, 2020
In early pregnancy the fetal skin allows fluid flow readily and the skin does not serve as a barrier to fluid movement. Amniotic fluid can in this condition be regarded as an extension of fetal extracellular fluid with the amnion as the fluid limiting membrane. Following mid gestation the fetal skin keratinizes and establishes a barrier between fetal extracellular fluid and the amniotic fluid. Composition of the amniotic fluid after this stage no longer reflects the fetal fluid compositions. Even so, a close relationship exists between fetal conditions and the composition of liquor amnii. Near term the fetus drinks about 400 ml of amniotic fluid per day and an equal volume is excreted into the amniotic cavity. Various types of cells are shed into the amniotic fluid and chemical compounds from the fetal lungs also find their way to the amniotic cavity. Abnormally, significant amounts of meconium may be passed heralding fetal distress.28 Although an indirect approach, characterization of the amniotic fluid provides valuable data from which fetal conditions may be assessed by extrapolation.
Amniotic Bands
Published in Amar Bhide, Asma Khalil, Aris T Papageorghiou, Susana Pereira, Shanthi Sairam, Basky Thilaganathan, Problem-Based Obstetric Ultrasound, 2019
Amar Bhide, Asma Khalil, Aris T Papageorghiou, Susana Pereira, Shanthi Sairam, Basky Thilaganathan
Amniotic bands occur as a consequence of a disruption to the amnion with an intact chorion. In most cases, amniotic bands occur without any associated fetal effects, though occasionally a diagnosis of amniotic band syndrome may be made because of associated fetal anomalies. Amniotic band syndrome is believed to be caused by entrapment of fetal parts (usually a limb or digits) in fibrous amniotic membrane while in utero. When the amnion ruptures, fetal parts may protrude into the extra-embryonic coelom and the amniotic membrane can entangle various fetal parts, thereby reducing blood supply and causing congenital abnormalities (typically resulting in amputations). Although no two cases are exactly alike, there are several features that are relatively common: syndactyly, distal ring constrictions, shortened bone growth, limb length discrepancy, distal lymphedema, and congenital bands. Very confusingly, by the time amniotic band syndrome is suspected, the amniotic bands are no longer visible, as the fetal insult probably occurred early in the first trimester.
Comparative Assessment of Short-Term Tendon-Scleral Postoperative Inflammation and α-Smooth Muscle Actin Expression following Oral and Topical Diclofenac Administration for Strabismus Surgery in Rabbits
Published in Current Eye Research, 2023
Anna Puspitasari Bani, Ikhwanuliman Putera, Eka Susanto, Rina La Distia Nora
The presence of early fibrotic reaction and collagen deposition, which might arguably lead to long-term fibrosis, would contribute to a mechanical restriction that may complicate re-surgery if it is performed, particularly in complex cases. Adhesion involving muscle/tendon, sclera, and conjunctiva has been observed intraoperatively.32,33 Several experiments to prevent excessive fibrosis using rabbits have been reported prior to our study. Amnion membrane placed in the scleral bed or surrounding the recessed/resected muscle showed inconsistent results. Amnion membrane could dampen inflammation, thus reducing fibrosis.9,10 However, the occurrence of xenograft rejection had been also reported and associated with more severe inflammation and fibrosis.34 With regard to antifibrotic agents, mitomycin-C, 5-fluorouracil, infliximab, and tranilast eye drop showed promising results.11–15 Of note, these antifibrotic drugs may not always be readily available, limiting their utility in clinical settings. Hence, our study using diclofenac, which is relatively more affordable, may serve as an alternative to reduce postoperative inflammation following strabismus surgery.
Effect of umbilical cord length on early fetal biomechanics
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Juan Felipe Sánchez Gutiérrez, Mercedes Olaya-C, Jorge Andrés Franco, Johana Guevara, Diego Alexander Garzón-Alvarado, María Lucía Gutiérrez Gómez
The amnion, enclosing the amniotic cavity containing the fetus and AF, was modelled with rectangular elements with a mass of 10−6 kg and a planar density of 1 kg/m2. The physical boundary of the fetus was determined by the amnion. The amniotic sac had negligible elemental differential mass (almost neglected mass simulating the soft tissue that represents the amnion). A total of 19 elements were connected by rotational joints to simulate the amniotic sac movement under hydrodynamic pressure and mechanical loads. Rotational joints represent the viscoelastic behavior of the amnion, and the fluid filled effect of the amniotic sac that maintain this structure with a quasi-spherical shape. Moreover, this structure can absorb and return mechanical energy, due to the fetus shocks against the amniotic sac wall, thus representing fetal dynamics.
Skin substitutes for acute and chronic wound healing: an updated review
Published in Journal of Dermatological Treatment, 2020
Christina Dai, Shawn Shih, Amor Khachemoune
Amion has been used as a biological dressing for burns since 1910 (4). It is a thin semi-transparent tissue from the innermost layer of fetal membrane (24). The benefits of using biological skin substitutes compared with biosynthetic skin substitutes include the construction of more natural dermis because of their native extracellular membrane structure and the presence of a basement membrane (24). It is one of the most effective substitutes for partial thickness burn wounds because it is derived from human placenta at the time of delivery (27). Although it is efficacious in protecting the wound bed and reducing bacterial load, it has poor mechanical stability (28). It can be prepared in multiple forms: fresh, dried, frozen, freeze dried irradiated, stabilized, or cryopreserved (27). Its usefulness in full thickness wounds was studied by comparing the effects of multi-layered amnion, mono-layered amnion, and Integra combined with a split thickness skin graft (STSG) in 40 porcine wounds. Results showed that the defects treated with multi-layered amnion exhibited less bleeding, inflammation, and infections than Integra but also showed a clinical course similar to STSGs alone (29).