The scanning electron microscopy of scolices in a case of hydatid cyst from human liver.

The scanning electron microscopic (SEM) features of hydatid scolices from a case of hydatid disease of the liver are described. The scolex when fully everted has a double circle of hooklets which occupy a large area of the parasite. The hooklets are inserted into the rostellum with one row of hooklets overlapping the other. Each hooklet is about 20 to 40 um long, has a basic round structure sharp at the distal end and broadens as it curves towards the point of insertion at the rostellum, where 2 blunt projections correspond to the 2 annular bundles of muscle fibres at the orifice of the scolex. The function of the hooklets is not fully understood but they are possibly used for anchorage and/or for the purpose of propulsion in a fluid medium by the act of invagination and evagination of the hooklets.

Filtration of cryoprecipitate: a microscopic assessment of filter depostion.

A recent survey indicated that many Canadian hemophiliacs and physicians did not consider it necessary to filter cryoprecipitate prior to infusion. Experiments were performed to demonstrate that no loss of factor activity resulted from filtration of cryoprecipitate through standard blood filters. Furthermore, examination of the material retained on standard and ultrafiltration elements using scanning and transmission electron microscopy demonstrated the presence of amorphous and fibrillar proteins that proved to be largely composed of fibrin. This was accompanied by cellular material including intact and disintegrating leukocytes, erythrocytes, and platelets. Nonbiologic material was also discovered, including cellulose and plastic debris. This study emphasizes the need for effective filtration of cryoprecipitate.

Intercellular junctions of antennal gland epithelial cells in the crayfish, Orconectes virilis. A freeze-fracture study.

Labyrinth and nephridial canal cells of the crayfish (Orconectes virilis) antennal gland possess two types of intercellular junctions revealed by freeze-fracture studies. Apical margins of the cells are connected by long septate junctions. In replicas, these junctions consist of many parallel rows of 80--140 A intramembrane particles situated on the PF membrane face (EF and PF fracture faces of Branton et al., 1975). Rows of pits are found on the EF fracture face and are deemed complementary to the rows of particles. Moreover, lateral margins of basal regions of the epithelial cells are attached by many intercellular junctions. These contacts are characterized in thin plastic sections by a narrow dense cytoplasmic plaque located subjacent to the plasma membrane at sites of adjoined cells, and 5 to 12 fine strands of dense material that extend across the intercellular gap between adjoined cells. In freeze-fracture replicas, EF intramembrane faces basal to the region of the plasma membrane containing septate junctions exhibit numerous discoid clusters of particles. The particle aggregates, assumed to represent freeze-cleave images of adhering junctions, range from 900 to 3,700 A in diameter, with individual particles about 185 A in diameter. These junctions appear to connect epithelial cell processes formed by basal infoldings of the plasmalemma, and occur between adiacent cells as well as adiacent processes of a single cell. The discrete aggregates of particles resemble replicated desmosomes (Shienvold and Kelly, 1974) and hemi-desmosomes (Shivers, 1976); therefore, they probably do not constitute a basis for electrical coupling between antennal gland epithelial cells.