Cytologic sexing of marine mussels (Mytilus edulis)

Four hundred eighty mature marine mussels (Mytilus edulis) were collected in late April from a mussel lease in an estuary in Prince Edward Island, Canada. Squash preparations made of reproductive gland (mantle) tissue of each mussel were stained with Wright-Giemsa stain and were examined by one investigator using light microscopy for sex determination. A strip of mantle tissue was also removed from each mussel, fixed in 10% buffered formalin solution, and processed for histologic evaluation. The sex of each mussel was determined independently by evaluation of the histologic preparations by a second investigator. The evaluation of cytologic preparations of mantle tissue was highly accurate in determining mussel sex, in that all 480 mussels (261 females and 219 males) were correctly identified when compared with the traditional standard of histologic sexing. No hermaphrodites were observed. The advantages of the cytologic procedure over traditional histologic processing include ease of sample preparation and evaluation, short preparation time, low cost, and sparing of tissue for other studies.