BUCCAL GLANDS OF ADULTS OF THE LAMPREY MORDACIA-MORDAX INCLUDING COMPARISONS WITH OTHER SPECIES

Mordacia mordax is one of the two anadramous parasitic lamprey species of the southern hemisphere family Mordaciidae. Its adults possess two lateral buccal glands and one central buccal gland. When the tongue-l ike piston is retracted, the buccal glands occupy much of the opening of the oral cavity at the rear of the buccal cavity. The glands contai n numerous tube-like, ductless secretory units, which discharge direct ly into the buccal cavity. Their secretory epithelial cells contain nu merous granules, some of which are zymogen-like, while others have a b eaded, spiralled appearance, The similarity of the latter to mast cell granules suggests that they may likewise produce an anticoagulant, wh ich would be valuable to a presumed blood feeder such as M. mordax. Th e mucus produced by these cells could act as a carrier for the secreti ons and as an adhesive for promoting retention of the secretions on th e host's surface. When the young adult is transferred to salt water, t he buccal glands increase their production and discharge of secretions . Since the glands are not enclosed in musculature, their secretions a re probably discharged by mechanical pressure applied by the forward m ovement of the head of the tooth-bearing piston into the buccal cavity . An account is given of the way in which the location, number, glandu lar organization, secretory granules, and type of secretion of the buc cal glands of M. mordax, and thus presumably also their mode of functi on, differ markedly from those of members of the other lamprey family found in the southern hemisphere, and of all holarctic lampreys. (C) 1 995 Wiley-Liss, Inc.