The identity of pseudocoelomic membranes and connective tissue in some nematodes

Ultrastructural aspects of feeding and secretion–excretion by the equine parasite Strongylus vulgaris

Light, scanning, and transmission electron microscopy were employed to provide further data on the putative origins of the immunogenic secretory–excretory product (ESP) of Strongylus vulgaris (Looss 1900). The sharply delineated but superficial attachment to the equine caecum by the mouth leaves behind an oval area devoid of epithelial cells. Attachment does not extend deeply enough to reach the muscularis mucosa layer of the equine intestine. The progressive digestion of the ingested plug of tissue (epithelial cells, blood cells and mucous) was visualized. The coelomocytes, floating cells and membranous structures located in the pseudocoelom and intimately associated with the digestive, excretory and reproductive systems, and with the somatic muscles are described. The secretory–excretory system comprises two, ventrally-located, secretory–excretory glands connected to tubular elements. These glands synthesize granules of various sizes and densities that are delineated.

Mechanical integration of muscle, tegument, and subtegumental tissues by anchoring fibrils and microfibrils in the cestode Hymenolepis diminuta

Electron microscopic examination of the epidermal basement membrane region of the rat tapeworm, Hymenolepis diminuta, has revealed specialized connective tissue structures that appear to anchor the epidermis, or tegument, to the parenchymal tissues of the helminth, as well as interconnect subtegumental muscle fibers, tegument, and parenchyma. Anchoring fibrils-cross-banded bundles of ca. 3 nm diameter filaments--were observed to directly interlink tegument and muscle, muscle and muscle, and tegument, muscle, and parenchymal connective tissue. Anchoring fibrils therefore appear to mechanically integrate epidermal tissue movements in response to subtegumental muscle contraction. A well-developed stratum of microfibrils, forming the lamina reticularis of the tegumental basement membrane, may also help anchor the tegument as well as to serve as a flexible, reinforcing sheath that protects parenchymal tissues from excessive radial displacement due to muscle contraction.