Fig. 1
From: Parasites, pathogens and commensals in the “low-impact” non-native amphipod host Gammarus roeselii
Parasites and pathogens observed during the histological screen of Gammarus roeselii. a External rotifers (white arrow) and stalked ciliated protists (black arrow) clustered around a gill filament (GF). b Externally associated ciliated protists (white arrow) and filamentous bacteria (black arrow) clustered around a gill filament (GF). c Ciliated protists (white arrow) embedded into the gill filament (GF). d Ciliated protists (white arrow) present in the blood stream (blood cell = black arrow) of the gill filament (GF). e Dense cluster of gregarines (black arrow) in the gut alongside bolus, gonad and hepatopancreas (HP). f Putative nuclei-targeted gut epithelia virus displaying nuclear hypertrophy due to expanding viroplasm (arrows) (GM = gut muscle). g Putative rickettsia-like organism in the cytoplasm of hepatopancreatocytes (white arrow). The nucleus (black arrow) is unaffected. h Digenean trematode (black arrow), present with external pearling (white arrow), encysted internally within G. roeselii. i Polymorphus sp. encysted internally within G. roeselii. j An unidentified microsporidian pathogen in the cytoplasm of infected hepatopancreatocytes. Developing (black arrow) and mature spore stages (white arrow) of the pathogen can be clearly identified in separate cells. Scale-bars: a, h, i, 100 μm; b-e, g, 50 μm; f, j, 10 μm