Microvascular anatomy of the non‐lobulated liver of adult Xenopus laevis: A scanning electron microscopic study of vascular casts

Abstract

The microvascular anatomy of the non-lobulated liver of adult Xenopus laevis was studied by scanning electron microscopy of vascular corrosion casts.Hepatic portal veins and hepatic arteries entered hepatic lobes at the hiluses, hepatic veins left at these sites. Intraparenchymal, hepatic portal veins branched up to 10 times before terminal portal venules supplied liver sinusoids. Hepatic arteries closely followed portal vessels. Arteriolar side branches formed anastomoses with close by portal venules (arteriolar-portal anastomoses; APAs), liver sinusoids (arteriolar-sinusoidal anastomoses; ASAs), and peribiliary plexus vessels. Distally, hepatic arteries anastomosed with terminal portal venules having >100 μm in diameter. Liver sinusoids formed a dense three-dimensional network displaying signs of non-sprouting and sprouting angiogenesis evidenced by "holes" and blind ending tapering cast vascular structures (sprouts), respectively. Sinusoids drained via efferent hepatic veins. Right and left hepatic veins drained into the posterior caval vein. Locally, a dense honeycomb-like 3D-meshwork of resin structures was found around terminal portal venules and hepatic arteries. These networks were fed by hepatic arterioles and drained into adjacent terminal portal venules. As their morphologies differed significantly from sinusoids and they were found at sites where diffuse lymphoid tissue is described, we are convinced that they represent the vasculature of diffuse lymphoid tissue areas. Frequencies and diameter ratios of hepatic portal venules versus hepatic arterioles anastomosing with the former (APAs) implicate that the arterial supply contributes to the oxygenation of parenchymal and stromal cells rather than to a significant increase in blood flow towards hepatic sinusoids.

A cigar in the left hand, a paintbrush in the right: Illustration and the anatomical sciences

“…These students exude talent. All five works complement the science performed by the researchers of the three chosen studies (Lametschwandtner et al, 2022; Mestriner et al, 2022; Perrone & Williams, 2022) and any one of them would have added extra layers of depth and interest to the journal. Although it is obvious, sometimes we need such reminders that the world of science is inherently intertwined with the world of art and illustration.…”

“…Cover artwork and design by Delaney Maxwell. African clawed frog, Xenopus laevis (foreground), and the microvascular anatomy of its non‐lobulated liver revealed via scanning electron microscopy (background) from Lametschwandtner et al (2022)…”

“…A panel of experts, namely Mr. Daugherty and editorial staff of The Anatomical Record, in addition to the authors, voted on a winning design. Maxwell's image (Figure 1) adeptly encapsulates the essence of the research by Lametschwandtner et al, who examined the hepatic microvascular of an African clawed frog (Lametschwandtner et al, 2022). Maxwell blends blues and greens to create vast intrahepatic portal venous and sinusoidal networks, and imbues depth and interest with occasional reds for the hepatic arterial supply.…”

“…Cover art projects generated for The Anatomical Record by Biomedical Visualization students from University of Illinois at Chicago. Upper left: Cover submission by X. Jiao showing histological imagery of dental ontogeny in Silesauridae from Mestriner et al (2022); upper right: Cover submission by Y. Li showing biomodels of the porcine femoral head from Perrone and Williams (2022); lower left: Cover submission by A. Pardieck showing vasculature of the liver in the African clawed frog from Lametschwandtner et al (2022). Lower right: Cover submission by K. Vasquez showing artist's reconstruction of a silesaurid dinosauriform as in Mestriner et al (2022)…”

“…These students exude talent. All five works complement the science performed by the researchers of the three chosen studies (Lametschwandtner et al, 2022;Mestriner et al, 2022;Perrone & Williams, 2022)…”