Studies on the lymph system of digenetic trematodes

Abstract

A survey is made of the literature pertaining to lymph systems of the various groups of trematodes in which they occur, together with descriptions of the lymph systems in several forms not previously studied. The author reports the presence of a lymph system in two families, Cyclocoelidae and Heronimidae, which heretofore were considered to be without such organs, and the significance of this characteristic feature of certain trematodes is discussed as bearing on the problem of the evolution of monostomes, amphistomes, and other distomes. The gross morphology and the histology of the structural units of the system are described for Paramphistomum stunkardi, an amphistome from a fish, and for Diplodiscus temporatus, an amphistome from an amphibian, together with observations on the ramifications and structural components of the system in Cotylophoron cotylophorum. Various theoretical considerations concerning the development, function, and taxonomic and phylogenetic significance are treated on the basis of the morphology of the system and its resemblance to certain components of the vascular system of higher forms. The lymph system in trematodes is the natural starting‐point in any study of the phylogenetic development of vascular systems.

Studies on the ultrastructure and histochemistry of the lymph system in three species of amphistome (Trematoda: Digenea) Gigantocotyle explanatum, Gastrothylax crumenifer and Srivastavaia indica from the Indian Water Buffalo Bubalus bubalis

“…The distribution of lymph vessels in the three species of amphistome examined conforms with descriptions of the system in various other amphistomes from ruminants (STUNKAUD, 1929;OZAKI, 1952; TANDON, 1960 a, b; GUPTA & DUTTA, 1967; SIIARMA & RATNU, 1982). The single pair of main longitudinal vessels found in these amphistomes contrasts with the three pairs reported in amphistomes from other vertebrates (Looss, 1902, STAFFORD, 1905STUNKARD, 1929;WILLEY, 1930;JORDAN & REYNOLDS, 1933). Contrary to observations made by previous authors (WILLEY, 1930;JORDAN & REYNOLDS, 1933;LOWE, 1966;SHARMA & RATNU, 1982), no evidence was found for the penetration of lymph vessels into the epithelium or tissues of any organ system, including the pharynx and acctabulum.…”

“…The single pair of main longitudinal vessels found in these amphistomes contrasts with the three pairs reported in amphistomes from other vertebrates (Looss, 1902, STAFFORD, 1905STUNKARD, 1929;WILLEY, 1930;JORDAN & REYNOLDS, 1933). Contrary to observations made by previous authors (WILLEY, 1930;JORDAN & REYNOLDS, 1933;LOWE, 1966;SHARMA & RATNU, 1982), no evidence was found for the penetration of lymph vessels into the epithelium or tissues of any organ system, including the pharynx and acctabulum. Usually a thin layer of parenchyma was interposed between the lymph vessel and the juxtaposing organ.…”

“…LOWE (1966) affirmed that the walls of the lymph vessels in two species of rumen amphistome were composed of 'connective fibres* while those in a third species were 'entirely membranous'. Most other investigators have asserted that the walls are simply membranous (STUNKARD, 1929;WILLEY, 1930;OZAKI, 1937OZAKI, ,1952SHARMA & RATNU, 1982). The present ultrastructural studies have revealed that the lymph vessels in Gastrothylax crumenifer, Gigantocotyle explanatum and Srivastavaia imlica are delimited by a unit membrane and separated from adjacent cells by a thin layer of interstitial material.…”

“…Looss (1902) proposed the term 'lymphgefassystem' for these channels due to their close association with the gut caeca and their resemblance to the lymphatic vessels of vertebrates. In live specimens the contents of these channels are plasma-like and are pushed back and forth by general body movements (STUNKARD, 1929;WILLEY, 1930WILLEY, , 1935OZAKI, 1937) or by specific peristaltic contractions of the lymphatic walls (Looss, 1902;LOWE, 1966;ROHDE, 1962ROHDE, , 1963SHARMA & RATNU, 1982). Definite cells, variously described as lymphocytes (in Paramphistomum stunkardi, Diplodiscus temperatus and Cotylophoron cotylophorum by WILLEY, 1930; and in Orthocoelium scoliocoelium by SHARMA & RATNU, 1982), haemocytoblasts (in D. temperatus by JORDAN & REYNOLDS, 1933), haemocytes (in Megalodiscus temperatus by CHENG & STREISFELD, 1963), or simply cellular elements (in Amphistomum spinulosum and in five genera of Angiodictyidae by Looss, 1902; and in C. cotylophorum by STUNKARD, 1929), have been reported within the lymphatic fluid.…”

Histochemical distribution of succinic dehydrogenase in the lymphatic system of a trematode Ceylonocotyle scoliocoelium

“…Literature covering the lymphatic system of trematodes relates mainly to their morphology and ultrastructure (Looss, 1902;Stunkard, 1929;Willey, 1930;Ozakai, 1937;Tandon, 1960;Lowe, 1966;Strong and Bogitsh, 1973). However, the involvement of this system in aspects of the physiology of such a worm has not been determined.…”