The ultrastructure of the reproductive system of mature (54-day-old), immature (32-day-old) and females from unisexual infections of Schistosoma mansoni is described in detail. The uterus is tegumentary in structure but the vitelline duct and oviduct are complex and possess cilia as well as lamellae on their luminal surfaces. The characteristics of the cells forming the walls of the ducts suggests that they may have a digestive function. The posterior portion of the oviduct of the adult worm contains sperm which become enveloped by lamellae. The vitelline cells of the adult contain vitelline droplets, much lipid and little glycogen. A second type of body derived from endoplasmic whorls is also present. Mehlis's gland contains only one type of gland cell and these cells pass through the ootype wall and open into its lumen. The female from unisexual infections has an incompletely developed Mehlis's gland, an ovary in which the Golgi complexes do not produce typical cortical granules and has vitelline cells which remain immature. The oviduct, ootype and uterus are well developed in contrast to the vitelline duct. A comparison with young, but not inseminated worms, suggests that the presence of sperm in the oviduct is not the major stimulus which induces maturation of the female worm.
1. Studies, using serial sections and a method of numerical assessment of the, numbers of cercariae in the various tissues, have shown that cercarial entry occurs through the skin at any point along the length of the fish and also through the gills and pharynx in the head region. The distribution of penetration along the length of the body is not uniform but exhibits a marked concentration in the head region.2. As the time after infection increases, this initial unimodal distribution is maintained and becomes even more restricted.3. Nearly all the cercariae have localized in the eye 12–24 hr. after infection. The few that remain outside the eye after this period appear to be moribund and undergoing phagocytosis.4. The majority of migrating cercariae are present in connective tissue and muscle. Very few occur in the blood system and even fewer in the other organs of the body. The numbers in the blood system show a local anterior concentration in the blood vessels anterior to the heart and in the region of the gills. It seems probable that the blood system does not form the major route of migration.5. Entry into the eye may occur at any point.6. Cercarial migration causes extensive tissue damage, but this is fatal only when major blood vessels are perforated and severe internal haemorrhage results. Interference with the nervous system and lateral line system may be the cause of the orientation disturbances which are sometimes noted within 12 hr. after infection.7. It is suggested that migration through the tissues is achieved mainly by the action of the anterior spination and that the function of the penetration gland cells may be lubricatory and/or adhesive rather than lytic.8. The restricted tissue distribution during migration and the retention of an essentially unimodal distribution of cercariae along the length of the body through-out the whole period of migration suggest that localization in the lens is not achieved by chance migration.
This paper describes a spraying method of producing iso-atomic droplets ( 2 3 um diameter) of uniform size, distribution and chemical composition. These droplets were used to calibrate a TEAM system operated under given conditions, so that the relative sensitivity of the instrumentation for the elements Nay Mg, P, S , (Cl), K, Ca and Co ('overall sensitivity factors') could be determined. These factors (15, 40, 83, 90, (43), 104, 109, lOO",, respectively) were used to convert observed X-ray intensity ratios from standard droplets to relative amounts of elements with a fair degree of accuracy (error generally less than f lo.,,). It was proposed that the sampling and quantification methods could be applied for the absolute quantitative bulk-analysis of fluids and tissues (after solubilization) with an introduced reference element, e.g. cobalt, and potentially to the study of relative elemental ratios in fluid microvolumes and in biological thin sections.
SUMMARYThe long-term, in vivo effects of a single, subcurative dose (200 mg/kg body weight of mouse) of praziquantel on the structure of adult Schistosoma mansoni and on the process and speed of tegumental repair are described. In both male and female worms praziquantel caused often extensive damage to the tegument, in the form of surface blebbings, swellings and lesions, and vacuolization and disruption of the subtegumental tissues. Repair of the drug-induced tegumental damage occurred slowly with partial and, more rarely, complete repair only being seen after 65 days post-treatment (p.t.), although signs of damage were still observed, particularly in male worms, at 100 days p.t. In contrast, repair of damage to the subtegumental/parenchymal tissues including the tegumental perikarya occurred relatively quickly, with the majority of worms examined appearing normal by 8–12 days p.t. The possible role(s) of the host immune response in relation to the speed of tegumental repair in vivo is discussed.
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