Wharton's jelly area and its association with placental morphometry and pathology

Gross and histological examination of Wharton's Jelly in the equine umbilical cord

Wharton's jelly (WJ) is fundamental for the well-being of the fetus, binding to the umbilical vessels and protecting them from twisting and compression. Gross and microscopic studies have been undertaken on the umbilical cord (UC) of human placentae in both normal and high-risk pregnancies, however there is limited research on equine UC. The aim of this study was to describe microscopically and immunohistochemically the equine UC in normal pregnancies, with particular attention to WJ. Forty-seven healthy mares, with no complications during pregnancy, admitted to the hospital for attending delivery were enrolled. Clinical data was collected at foaling on foal health and placental characteristics. UC samples were collected from three sites (amniotic, allantoic and in the region of vein anastomosis) for histology. The thickness of different layers of arteries and veins and WJ in different UC portions were measured (μm). Wharton's Jelly was weighted (g) and its sections were stained with Masson's trichrome, orcein technique and silver impregnation. Immunohistochemistry was undertaken using antibodies raised-against collagen type I, V, VI and fibrillin. Forty-seven UCs, from 19 colt and 28 filly foals, were analyzed for WJ weight and 8/47 UCs were examined histologically. Warton's jelly was only found in the amniotic portion of the UC closest to the foal's abdomen. The weight of WJ (4.0 ± 3.3 g) did not vary between colts and fillies and it was not correlated with any of the clinical or UC parameters measured. The tunica media of arteries and veins was thicker in the amniotic portion of the UC, as described in human UCs in late pregnancy. This finding could be an adaptation to aid in resisting compression because of fetal movements and UC twisting. The umbilical vein was thicker than the umbilical arteries in the tunica media and tunica adventitia in the sections examined throughout the length of the cord. This preliminary study describes gross and histological WJ's structure in the equine species. However, further studies are required to better characterize UC's changes throughout pregnancy and in the presence of mare's or fetal disease.

Pregnancy and umbilical cord pathology: structural and functional parameters of the umbilical cord

Scientific research in the field of physiology and pathology of the umbilical cord is quite limited and imperfect. The purpose of the study was to evaluate the histological architecture of the pathological umbilical cord and investigate the relationship between the main parameters and placental postnatal macromorphometric characteristics, which serve as a reflection of placental dysfunction. Four groups of patients were included, each undergoing a postnatal histological and topographic examination of the umbilical cord: Wharton's jelly edema (10 samples), velamentous cord insertion (10 samples), single umbilical artery (10 samples), and physiological pregnancy (10 samples). Compared to the control group, all newborn groups exhibited changes in umbilical vessel morphology, characterized by an increased Wagenworth index and a decreased Kernohan index. The functional indices of the umbilical vessels were found to be most severely affected in cases of Wharton's jelly edema. In cases of single umbilical artery, the changes in vascular functional parameters indicated their compensatory remodeling with the highest Wagenworth and Kernohan indices of the umbilical vein. Deviation from the normal average placental weight was observed in cases of Wharton's jelly volume pathology or velamentous cord insertion. However, in the case of a single umbilical artery, there were no significant deviations in the macromorphometry of the placenta.

Considering the Effects and Maternofoetal Implications of Vascular Disorders and the Umbilical Cord

The umbilical cord is a critical anatomical structure connecting the placenta with the foetus, fulfilling multiple functions during pregnancy and hence influencing foetal development, programming and survival. Histologically, the umbilical cord is composed of three blood vessels: two arteries and one vein, integrated in a mucous connective tissue (Wharton's jelly) upholstered by a layer of amniotic coating. Vascular alterations in the umbilical cord or damage in this tissue because of other vascular disorders during pregnancy are worryingly related with detrimental maternofoetal consequences. In the present work, we will describe the main vascular alterations presented in the umbilical cord, both in the arteries (Single umbilical artery, hypoplastic umbilical artery or aneurysms in umbilical arteries) and the vein (Vascular thrombosis, aneurysms or varicose veins in the umbilical vein), together with other possible complications (Velamentous insertion, vasa praevia, hypercoiled or hypocoiled cord, angiomyxoma and haematomas). Likewise, the effect of the main obstetric vascular disorders like hypertensive disorders of pregnancy (specially pre-eclampsia) and chronic venous disease on the umbilical cord will also be summarized herein.

Assisted Reproductive Technique and Abnormal Cord Insertion: A Systematic Review and Meta-Analysis

Abnormal cord insertion (ACI) is associated with adverse obstetric outcomes; however, the relationship between ACI and assisted reproductive technology (ART) has not been examined in a meta-analysis. This study examines the association between ACI and ART, and delivery outcomes of women with ACI. A systematic review was conducted, and 16 studies (1990–2021) met the inclusion criteria. In the unadjusted pooled analysis (n = 10), ART was correlated with a higher rate of velamentous cord insertion (VCI) (odds ratio (OR) 2.14, 95% confidence interval (CI) 1.64–2.79), marginal cord insertion (n = 6; OR 1.58, 95%CI 1.26–1.99), and vasa previa (n = 1; OR 10.96, 95%CI 2.94–40.89). Nevertheless, the VCI rate was similar among the different ART types (blastocyst versus cleavage-stage transfer and frozen versus fresh embryo transfer). Regarding the cesarean delivery (CD) rate, women with VCI were more likely to have elective (n = 3; OR 1.13, 95%CI 1.04–1.22) and emergent CD (n = 5; OR 1.93, 95%CI 1.82–2.03). In conclusion, ART may be correlated with an increased prevalence of ACI. However, most studies could not exclude confounding factors; thus, further studies are warranted to characterize ART as a risk factor for ACI. In women with ACI, elective and emergent CD rates are high.

Placental Tissues as Biomaterials in Regenerative Medicine

Placental tissues encompass all the tissues which support fetal development, including the placenta, placental membrane, umbilical cord, and amniotic fluid. Since the 1990s there has been renewed interest in the use of these tissues as a raw material for regenerative medicine applications. Placental tissues have been extensively studied for their potential contribution to tissue repair applications. Studies have attributed their efficacy in augmenting the healing process to the extracellular matrix scaffolds rich in collagens, glycosaminoglycans, and proteoglycans, as well as the presence of cytokines within the tissues that have been shown to stimulate re-epithelialization, promote angiogenesis, and aid in the reduction of inflammation and scarring. The compositions and properties of all birth tissues give them the potential to be valuable biomaterials for the development of new regenerative therapies. Herein, the development and compositions of each of these tissues are reviewed, with focus on the structural and signaling components that are relevant to medical applications. This review also explores current configurations and recent innovations in the use of placental tissues as biomaterials in regenerative medicine.

Current Perspectives of Prenatal Sonography of Umbilical Cord Morphology

The umbilical cord constitutes a continuation of the fetal cardiovascular system anatomically bridging between the placenta and the fetus. This structure, critical in human development, enables mobility of the developing fetus within the gestational sac in contrast to the placenta, which is anchored to the uterine wall. The umbilical cord is protected by unique, robust anatomical features, which include: length of the umbilical cord, Wharton’s jelly, two umbilical arteries, coiling, and suspension in amniotic fluid. These features all contribute to protect and buffer this essential structure from potential detrimental twisting, shearing, torsion, and compression forces throughout gestation, and specifically during labor and delivery. The arterial components of the umbilical cord are further protected by the presence of Hyrtl’s anastomosis between the two respective umbilical arteries. Abnormalities of the umbilical cord are uncommon yet include excessively long or short cords, hyper or hypocoiling, cysts, single umbilical artery, supernumerary vessels, rarely an absent umbilical cord, stricture, furcate and velamentous insertions (including vasa previa), umbilical vein and arterial thrombosis, umbilical artery aneurysm, hematomas, and tumors (including hemangioma angiomyxoma and teratoma). This commentary will address current perspectives of prenatal sonography of the umbilical cord, including structural anomalies and the potential impact of future imaging technologies.