Blood cells and coelomocytes of the inarticulate brachiopod Lingula anatina

Three cell types are described from the coelomic cavity of the pedicle of the brachiopod Lingula anatina . Erythrocytes are abundant in the blood vessels of the mantle and also occur, in reduced numbers, in the pedicle. Phagocytic amoebocytes, characterized by a variable number of electrondense, homogeneous granules are common in the coelomic fluid of the pedicle. The enigmatic spindle bodies described by earlier authors constitute the most common cell type encountered in the pedicle coelom of aquarium-maintained specimens. The origin of spindle bodies from muscle cells is suggested.