Hepatopancreas in the starving amphipod Ampelisca eschrichtii and the feeding amphipod Monoporeia affinis during vitellogenesis

Abstract A comparative analysis of the hepatopancreas of amphipod species Ampelisca eschrichtii and Monoporeia affinis collected on the northeastern shelf of Sakhalin Island (Okhotsk Sea) was carried out between 2013 and 2021 in summer and fall during the period of vitellogenic oocyte growth. As a result of different habitat conditions A. eschrichtii has seasonal starvation in summer and fall, while M. affinis has access to food. During the period of starvation, the hepatopancreas of A. eschrichtii exhibits the following characteristics: 1) the functional passivity of F-cells of the epithelium, which confirms the absence of food in the stomach of amphipods, 2) the R-cells destruction due to lipid utilization, 3) the activation of B-cells, which apparently digest membrane structures of destroyed R-cells. The morphology of R-, F- and B-cells of the epithelium of the hepatopancreas in M. affinis is consistent with the description of analogous cells of the epithelium of the hepatopancreas of decapods and provide evidence for the presence of a food in the habitat of this species. In M. affinis, in contrast to A. eschrichtii, R-cells appear to synthesize vitellogenin. The primary function of R-cells of A. eschrichtii during starvation is to provide previously stored nutrients (lipids) for oocyte vitellogenic growth and energy for vital function of the organism. Synthesis of vitellogenin in these cells is unlikely.