Morphological features of the human umbilical vein in normal, sickle cell trait, and sickle cell disease pregnancies.

Pathological changes often occur in the placenta of women with sickle cell disease (SCD). These alterations are caused by sickling of erythrocytes and vasoocclusion in the placental circulation, leading to regional hypoxia. However, the morphological status of the umbilical cord, which is in close physical association with the placenta, is not documented under such conditions. To explore this, the umbilical vein structure in healthy, sickle cell trait (the heterozygous state), and SCD pregnancies was studied using scanning (SEM) and transmission electron microscopy (TEM). Interestingly, the sickle cell trait umbilical vein architecture was morphologically similar to that in control veins, whereas numerous alterations were seen in the SCD umbilical vein wall. In SEM, the SCD umbilical vein endothelial cells showed atypical morphologies. TEM analysis of the tunica media showed (1) smooth muscle cell proliferation and increase in the thickness of the basement membrane underlying the cells; (2) areas of necrosis; (3) reduplication of the inner elastic lamina. Such features were often seen in sickle patients vasculature at autopsy. Our findings could have importance because tissue hypoxemia is an integral part of vasoocclusion. We conclude that the SCD umbilical vein may be an additional tool for studying vasoocclusion in sickle cell disease.

Allantoid duct, arteries and veins of the funiculus umbilicalis in bovines

Secciones transversales del funículo umbilical de 39 fetos de bovinos de la raza Holstein, fueron estudiados con microscopio de luz. Las secciones fueron cortadas en los tercios yuxtafetal, medio y yuxtaplacental y teñidos con hematoxilina-Eosina. Ambas arterias umbilicales y venas son caracterizadas por una túnica media espesa, siendo mucho más gruesa en la arteria que en las venas, gracias a la conspicua capa muscular, especialmente a nivel del tercio medio del cordón umbilical. Como regla el lumen de las venas es oval o elipsoide y relativamente más ancho que el lumen de las arterias el cual es estrellado, puntiforme o casi obliterado

Vasculature of bovine placentas studied by scanning electron microscopy of corrosion casts.

Corrosion casts, obtained after injection of Tensol or Mercox, from 10 placentas of Holstein breed cows, were studied. The investigation was performed in fetal cotyledons, which are attached to uterine caruncles to form units, called placentons. Arteries and veins form, together, vascular cylinders, with the venous half cartridge partially surrounding the arterial one. The morphological differences between arterioles and venules concern the type of distribution, branching, surface (nuclei, oblique folds, anular narrowings).