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

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Abstract
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.