Ultrastructure and cellular organization of longsnout seahorse Hippocampus reidi liver

Hippocampus reidi is an endangered tropical species, as well as being one of the most widely traded marine fish globally. The cellular organization of the normal liver in the longsnout seahorse (H. reidi) was studied using electron microscopy to provide an overview of the liver’s fine structure. Two hundred and fifty seahorses were collected and prepared for transmission electron microscopy. Sections were cut using an LKB ultramicrotome and then washed with PBS, stained with uranyl citrate for 2-3 min, and then with lead acetate for 20 s. The grids were then observed using an electron microscope Zeiss EM 109. The cytoplasm of the hepatocyte contains a nucleus surrounded by a double membrane, diffusely scattered mitochondria and a network of the endoplasmic reticulum of rough and smooth types. Most of the rough endoplasmic reticulum appear to be in parallel to the nuclear envelope or the cell membrane and was situated relatively in the center part of the cytoplasm. The cellular organization of the longsnout seahorse liver is quite similar to that of other mammalian species.