Revista Chilena de Historia Natural 80 (1): 55-62, 2007
RESEARCH ARTICLE
Epithelial sentinels or protozoan parasites? Studies on isolated rodlet cells on the 100th
anniversary of an enigma
Rodlet cells are an unusual cell type found exclusively in teleost fishes. Their principal
characteristics are a fibrous capsule and arrow or club-like structures pointing towards the apex of the cell, which are called rodlets.
Rodlet cells were first described by Thelohan (1892) as undetermined sporozoan fish parasites, and soon after named
Rhabdospora thelohani by Laguesse (1895). In 1906, a presently ongoing controversy started, with Plehn’s independent
characterization of rodlet cells as endogenous glandular cells, and a prompt refutation by Laguesse (1906). Both maintained their
position, and during the following century both views continued to coexist with varying popularity, while additional interpretations of
rodlet cell function were proposed. Here I present observations of live rodlet cells from the olfactory epithelium of the marine teleost
Isacia conceptionis. Rodlet ejection was monitored and the fate of rodlet cells and ejected rodlets was tracked for up to 12
h. While rodlet cells died within a few hours, usually after rodlet expulsion, the rodlets remained stable over the observation period.
These results are discussed in the light of the current hypotheses regarding rodlet cell function.
Key words:
fish, immune cell,
parasite, rodlet cell, teleosts
