A comparative study of the vitelline cell in Schistosoma mansoni, S. haematobium, S. japonicum and S. mattheei

SUMMARYA comparison is given of the ultrastructure of the vitelline cell in Schistosoma mansoni, S. haematobium, S. japonicum and S. mattheei. Four stages in development of the vitelline cell have been categorized as follows: Stage 1, the undifferentiated cell; Stage 2, the developing cell showing the beginning of synthetic activity; Stage 3, the developing cell showing active protein synthesis; Stage 4, the fully mature vitelline cell. These stages in development have been defined morphologically and Stages 1, 2 and 3 are very similar in all 4 species. Lipid is present in the Stage 4 cells of all species but appears earlier at Stage 3 in S. haematobium and S. mattheei. There are several differences as to the intercellular inclusions of the Stage 4 cells, the most marked of these being the absence of calcareous corpuscles from S. japonicum as compared with the other 3 species.

Schistosoma mansoni: an examination of the reproductive status of females from single sex infections

SUMMARYThe variation in the development of the reproductive system of female Schistosoma mansoni from single sex infections is described. Vitelline cell development was assessed by staining for phenolic substances and the development of Mehlis' gland and the ovary by electron microscopy. Although there was considerable variation in the development of worms from individual mice harbouring infections of the same age, the mean values indicated that there was a low level of differentiation and turnover of vitelline cells in worms 30–200 days post-infection. The proportion of females which possessed mature vitelline cells showed a general increase with age. The ovary was always in an immature stage but the development of Mehlis' gland showed some variation. The results suggest that the stimulus given by the male to the female is not necessarily to initiate development of the reproductive system but to increase the rate of development of the vitelline gland and to co-ordinate the development of the entire reproductive system.

Electron microscopy of embryonic envelope formation by the cestode proteocephalus longicollis (zeder, 1800)(proteocephalidea)

Four main embryonic envelopes, the capsule, outer envelope, inner envelope and oncospheral membrane, are formed around the developing embryos of Proteocephalus longicollis, a parasite of fishes.The capsule, formed from shell-globule material of vitelline cells, is the first embryonic envelope which encloses the fertilized oocyte and a single vitelline cell (Fig. 1) when they pass through the ootype and enter the uterus. At this initial stage of embryogenesis, the capsule is formed of two closely apposed membranes (Fig. 1, inset). In more advanced stages, the capsule slightly increases its volume, and a fine-fibrillar material accumulates in the space between its two limiting membranes (Fig. 2).

Physiological and histochemical observations on the adult liver fluke, Fasciola hepatica L. III. Egg-shell formation

1. The egg shells of Fasciola are derived from globules or granules contained in the, vitelline cells. These globules contain an orthodihydroxyphenol and protein.2. The anatomy and histology of the Mehlis's gland region have been described, and the site of liberation of the above granules has been isolated.3. Mechanical forces, due to the churning action of the uterus, are believed to be responsible for freeing most of the granules. This liberation can be correlated with the presence of spermatozoa in the uterus. The spermatozoa can penetrate the vitelline cells, but this does not free the globules.4. Active spermatozoa, in alkaline solutions, tend to form aggregates, and incorporate into these aggregates any solid material in the vicinity. This is apparently responsible for the arrangement of cells within the egg, and for the formation of a shell round it from fused vitelline cell globules.5. The polyphenol of the newly formed egg shell is oxidized into a quinone in the anterior uterine coils. Polyphenol oxidases have not been conclusively demonstrated. The relative uterine coils are surrounded by an especial concentration of a generally distributed tissue haemoglobin.6. The final egg shell is composed of a quinone tanned protein, similar to the sclerotin of the cockroach ootheca.7. Suggestions are advanced as to the possible functions of Mehlis's gland and Laurer's canal.