Comparative Fine Structure of Sclerotized and Unsclerotized Integument of the Rabbit Tick, Haemaphysalis leporispalustris (Acari: Ixodides: Ixodidae)1

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Abstract
Investigations into the fine structure of the integument of the rabbit tick, Haemaphysalis leporispalustris (Packard), show that the micromorphology of the hard and soft regions of the organism differs markedly. The cuticle of the hard integument consists of a thin unorganized subcuticle, a fibrous endocuticle, and a sclerotized, tanned exocuticle, all of which are penetrated by numerous pore canals containing electron-dense fibrils and granules. The procuticle is covered by a thin epicuticle, a complex structure consisting of at least 4 distinct regions. Underlying the cuticle is a single layer of epidermal cells containing numerous electron-dense granules which obscure most cytoplasmic detail. The cuticle of the soft integument also possesses an epidermal layer containing similar granules. The endocuticle is not distinctly lamellate and the exocuticle is apparently untanned. The electron-dense granules may be storage forms of precursors which may later be incorporated into new cuticle, which is actively produced during feeding and preceding final engorgement. Cuticular growth in the sclerotized areas probably occurs only interstadially.