Buccal glands of adults of the lamprey Mordacia mordax, including comparisons with other species

Abstract

Mordacia mordax is one of the two anadromous parasitic lamprey species of the southern hemisphere family Mordaciidae. Its adults possess two lateral buccal glands and one central buccal gland. When the tongue-like piston is retracted, the buccal glands occupy much of the opening of the oral cavity at the rear of the buccal cavity. The glands contain numerous tube-like, ductless secretory units, which discharge directly into the buccal cavity. Their secretory epithelial cells contain numerous granules, some of which are zymogen-like, while others have a beaded, spiralled appearance. The similarity of the latter to mast cell granules suggests that they may likewise produce an anticoagulant, which would be valuable to a presumed blood feeder such as M. mordax. The mucus produced by these cells could act as a carrier for the secretions and as an adhesive for promoting retention of t he secretions on the host's surface. When the young adults is transferred to salt water, the buccal glands increase their production and discharge of secretions. Since the glands are not enclosed in musculature, their secretions are probably discharged by mechanical pressure applied by the forward movement of the head of the tooth-bearing piston into the buccal cavity. An account is given of the way in which the location, number, glandular organization, secretory granules, and type of secretion of the buccal glands of M. mordax, and thus presumably also their mode of function, differ markedly from those of members of the other lamprey family found in the southern hemisphere, and of all holarrctic lampreys. © 1995 Wiley-Liss, Inc.

Relationships between the diets and characteristics of the dentition, buccal glands and velar tentacles of the adults of the parasitic species of lamprey

“…However, the buccal glands of M. mordax differ markedly from those of Northern Hemisphere blood‐feeding lampreys in both their number (3 vs. 2) and location (entrance to oral aperture vs. more posteriorly in the basilaris muscles). Furthermore, in contrast to the buccal glands of P. marinus , those of M. mordax possess numerous mucus cells and have neither a muscular wall nor a central lumen nor a duct leading into the oral cavity (Potter et al , 1995). These fundamental differences imply that the glands of M. mordax function differently from those of all other lampreys.…”

“…The location of the buccal glands of M. mordax at the entrance of the oral aperture means that these secretory structures lie particularly close to the host tissue. It has been proposed that, in M. mordax , the movement of the piston cartilage applies pressure to the buccal glands and thus causes its secretions to be released directly onto the adjacent wound, with their mucus component helping prevent the dissipation of lamphredin away from the wound (Potter et al , 1995). In contrast, in P. marinus , the lamphredin, which has been secreted into the lumen of those glands is forced forwards into the duct leading to the oral aperture as a result of pressure applied by the contraction of the muscular wall of the buccal glands.…”

“…The mean length of the two bean‐shaped buccal glands in the above species was expressed as a percentage of the lamprey's total length (TL). The dimensions of the three buccal glands of Mordacia mordax (Richardson, 1846), which lie at the entrance to the oral cavity, are taken from Potter et al (1995). The mean length of the two club‐shaped lateral glands of M. mordax was added to half the length of the central gland and this composite length was then expressed as a percentage of TL.…”

“…2f, h that originally appeared in Potter & Hilliard (1987); Wiley‐Blackwell for permission to use the image in Fig. 4b that originally appeared in Potter et al (1995) in Journal of Morphology ; and Canadian Journal of Zoology for permission to use the image in Fig. 5c.…”

“…Adult lampreys possess buccal glands, whose secretions (lamphredin) prevent the host blood from clotting and facilitate the breakdown of host tissues (Lennon, 1954; Baxter, 1956). These glands are paired and embedded in the basilaris muscles in all genera except Mordacia , in which these glands lie at the entrance to the oral cavity (Potter et al , 1995). The buccal glands in P. marinus are relatively larger than those of La.…”