Comparative Histological Study of Parenchymal Arrangements in Three Orders of Reptilian Livers

Abstract

This study presented detailed descriptions of parenchymal arrangements in the livers of 23 reptilian species using light microscopy, and extensively discussed this from a phylogenetic viewpoint. Hepatocyte sinusoidal structures (HSS) were classified into three different types: (I) the several-cell-thick plate type, (II) two-cell-thick plate type, and (III) one-cell-thick plate type. Parenchymal arrangements showed either the combined two-and one-cell-thick plate type or one-cell-thick plate type, whereas the sea snake in the sub-order Serpentes showed the several-cell-thick plate type. In the order Testudines, peripheral sinusoids near terminal portal veins were tortuous, becoming straighter toward terminal central veins. Melanomacrophages (MMs) were observed in sinusoidal capillaries in the order Testudinata, Crocodilia, and Squamata, but not in the sub-order Serpentes (except for the sea snake). This study showed that the architecture of the parenchymal arrangement was related to the phylogenetic relationship, whereas the distribution of MMs may not be. The MMs systems of turtles, alligators, and sea snakes, whose place of main habitation is underwater, may have adapted according to ecological and behavioral patterns. Based on the hepatic architecture of parenchymal arrangements and the distribution of MMs, it was suggested that reptilian livers acquired the division of three zones in the acinus.

Comparative liver morphology associated with the hepatosomatic index in five Neotropical anuran species

“…typhonius . The sinusoidal space is involved in many hepatic functions and is associated with the type of hepatocyte arrangement, in addition to its role in microcirculation (Akiyoshi & Inoue, 2004; Akiyoshi, Inoue, & Ondera, 2016; Inoue & Akiyoshi, 2003).…”

Melanomacrophage Centers: Comparative Histological Insights among Three Reptilian Species

“…The presence of melanin in MMCs is well documented (Akiyoshi et al, 2015;An andZhang, 2019, Manrique et al, 2019). Normally melanin is produced by melanocytes developed embryologically from the neural crest and enveloped with spherical to oval melanosomes.…”

“…In the genera, Hemidactylus and Plestiodon, the distribution of MMCs were in all hepatic regions, but MMCs were larger and widely observed in the sinusoidal capillaries. In the order Crocodilia, MMCs were of moderate size in sinusoidal capillaries (Akiyoshi et al, 2015). The phylogenetic order of the MMCs was however influenced by the number, sizeable, and locational heterogeneities, according to Akiyoshi et al (2015).…”

“…Red-eyed crocodile skinks (Tribolonotus gracilis) appeared in two forms, large polymorphic MMCs aggregates and small diffused macrophages scattered all over the hepatic tissue (Kwon et al, 2019). Akiyoshi et al (2015) designed a study on the livers of 23 reptilian species and they revealed the distribution of MMCs in different zones in hepatic parenchyma. MMCs, appeared in yellow to brown compounds, lining the sinusoids and protruding into the sinusoidal lumen.…”

“…In the order Crocodilia, MMCs were of moderate size in sinusoidal capillaries (Akiyoshi et al, 2015). The phylogenetic order of the MMCs was however influenced by the number, sizeable, and locational heterogeneities, according to Akiyoshi et al (2015). Variations in the number of MMCs, their size and distribution vary according to species, organ, age, nutritional status and environmental and stress conditions (Ribeiro et al, 2011;Pronina et al, 2014).…”