Article

Experimental & Applied Acarology

, Volume 1, Issue 3, pp 253-272

First online:

Fine structure of the ‘hindgut’ of the two-spotted spider mite,Tetranychus urticae, with special reference to origin and function

  • U. Mothes-WagnerAffiliated withDepartment of Zoology, Philipps University Marburg

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Abstract

The ultrahistology of the ‘hindgut’ of the spider miteTetranychus urticae is described, a new terminology of the histological portions, based on the presence and absence of cuticle, is presented, and functional characteristics are discussed.

The alimentary canal of the spider mite consists of the cuticle-lined foregut (pharynx, esophagus, esophageal valve), a cuticle-free midgut, and a cuticle-lined hindgut with anal slit. The portions of the midgut are the ventriculus with three cranial and two caudal caeca, and the posterior midgut with two distinct cell types. Both portions are separated by a sphincter. The anterior lateral walls of the ∇-shaped posterior midgut which terminates in the dorsal region of the ventriculus show histological variability. Cells are either asymmetrical with long apical projections (=typical transporting epithelium) or show resorptive characteristics and storage products (=resorptive epithelium). The dorsal and posterior lateral epithelium consists of flat glandular cells containing large granular secretion grana. It is suggested that these cells synthesize mucoid substances for the facilitation of excretion transport.

The differentiation and function of the posterior midgut epithelium are discussed with respect to the formation of different elimination products.