Embryonic intestine and faecal matter accumulation in the red stingray. (a) Ventral side of stage 32 embryo (the specimen is half-dissected to show the embryonic intestine). (b) Sagittal cross section through the intestine of a stage 32 embryo, and (c) its schematic representation. Note that the faecal matter only occupies the posterior half of the intestine. Scale bar = 500 µm.