Studies on the Fine Structure of a Gregarine Parasitic in the Gut of the Grasshopper, melanoplus differentialis*

Abstract

SYNOPSIS. Materials within the endoplasm of both the protomerite and deutomerite may be displaced and stratified by ultracentrifugation. Animals are not killed by this treatment, and in time a redistribution of stratified materials may occur. The electron microscope reveals numerous ultramicroscopic folds in the surface envelope which is composed of 3 membranes; the outer and middle cover the surface of the folds while the inner one continues as a smooth membrane over the ectoplasm. The contact surfaces of animals in syzygy do not show the small folds to be interlocked; instead, they are in fold‐to‐fold contact. Numerous relatively dense bodies which appear to be filamentous are sometimes observed immediately underneath or within the middle or inner membrane. Within the ectoplasm is an ultramicroscopic net‐like fibrillar structure much denser than the surrounding cytoplasm. This system of fibrils is composed of anastomosing elements varying from ∼ 50 to 200 Å in diameter. Certain of the larger fibrils are directly attached to the surface envelope at positions between the folds. A second filamentous structure within the ectoplasm appears to be tubular. Elements of this system also appear to join and penetrate the surface envelope by means of pores. A large amount of gelatinous secretion forms at the surface of the sporont; as it glides forward a trail of mucous is left behind. The actual mechanism involved in the gliding movement was unobserved, but evidence is lacking to support the view that the gliding movement is engendered by posteriorly directed “jets” of mucus.

The Ultra‐Structural Similarities between Cryptosporidium parvum and the Gregarines

“…Our observation of the fusion zone between the paired extracellular stages with a complete double membrane wrap was markedly similar to the recent in vitro observations for Cryptosporidium by Rosales et al (2005) via TEM. Indeed, this fusion junction resembles the fold-tofold contact of Gregarina rigida during the syzygy stage (Beams et al 1959). The polarity of the gamonts and their position during pairing may vary depending on species (Vavra and McLaughlin 1970).…”

“…Indeed, this fusion junction resembles the fold‐to‐fold contact of Gregarina rigida during the syzygy stage (Beams et al. ). The polarity of the gamonts and their position during pairing may vary depending on species (Vavra and McLaughlin ).…”

“…Another type of gamont orientation is the caudo‐frontal syzygy observed in Gregarinoidea, Porosporoidea (Sporozoa, Orthogregarinia) (Beams et al. ; Desportes and Schrével ; Rueckert et al. ; Toso and Omoto ) and the caudo‐caudal type in the Selenidiidae (Desportes and Schrével ).…”

“…(Desportes and Schr evel 2013), or the pairing in the latero-frontal syzygy in Porosporoidea Thiriotia pugettiae (Rueckert et al 2011). Another type of gamont orientation is the caudo-frontal syzygy observed in Gregarinoidea, Porosporoidea (Sporozoa, Orthogregarinia) (Beams et al 1959;Desportes and Schr evel 2013;Rueckert et al 2011;Toso and Omoto 2007) and the caudo-caudal type in the Selenidiidae (Desportes and Schr evel 2013). As shown in Fig.…”

Observations on the Fine Structure of the Ciliate Dileptus anser

“…I t is possible that this dense zone represents a system of poorly developed myonemes which may {function in support and/or in minor contractions of the organism. A similar system, although more highly organized, has been described in a related position in Gregarina rigida ( 2).…”