The structure of the cuticle ofAscaris lumbricoidesvar.suis

Abstract

1. Nine layers have been identified in the cuticle ofAscaris lumbricoidesvar.suisunder the light microscope and their nomenclature is identical with that of van Bömmel.2. The inner cortical layer consists of a distinct structure which is seen to be markedly different from the homogeneous layer when fresh frozen sections are examined under phase contrast.3. Examination of the outer surface of the cortical layer under the electron microscope after layer stripping and sectioning has revealed the presence of a ridged osmiophilic layer which is less than a thousand Ångström units thick.4. Longitudinal osmium-fixed sections, when examined under the electron microscope, have shown that the external cortical layer has radial striations which appear to link up with the striations which radiate from an aster-like process at the top of the structure arising from the ‘fibrillar layer’.5. The osmium-fixed homogeneous layer, when viewed under the electron microscope, is seen to consist of fine radial striations.6. The fibre layers do not show any finer structures when they are examined under the electron microscope. In longitudinal section, they are seen to consist of irregularly shaped fibres without an internal fibrillar structure. Layer stripping shows that they lack the type of periodic structure seen in collagen.7. The basal lamella is similar, in that the electron microscope does not reveal any finer structures.