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Malcolm K. Jones 《International journal for parasitology》1989,19(8):919-930
The cirrus pouch of Cylindrotaenia hickmani was examined by transmission electron microscopy. The cirrus pouch is a complex organ consisting of muscular, nervous and epithelial tissues. Muscles forming the cirrus pouch wall contain large myocytons that merge with myofibrils. Muscles supplying the gonadoducts within the pouch consist of small myocytons which are connected to associated myofibrils by elongate processes. Discrete neuromuscular junctions are commonly seen in both muscles. Two cells, thought to be neurons, are present in the pouch. The abundance of nervous tissue in the pouch is suggestive of a high level of neural control of the activity of that organ. The cirrus is lined by filamentous, hook-like and blade-like microtriches. Ciliated sensory receptors are found among the microtriches lining the cirrus. Epithelial cytons associated with proximal regions of the cirrus produce a material which is secreted from the syncytial cytoplasm of the cirrus. Intercellular junctions, resembling gap junctions, are common among the cells associated with the cirrus. The complexity of the cirrus pouch of C. hickmani suggests that this organ may prove valuable for studies on neuromuscular physiology and cellular interactions in cestodes. 相似文献
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Michael M. Driessen 《Austral ecology》2019,44(6):1030-1039
Understanding species’ responses to fire regimes, particularly rare or threatened species, is important for land managers tasked with managing for biodiversity. Hickman's Allanaspides (Allanaspides hickmani, Anaspidesidae) is a rare, primitive, shrimp‐like crustacean, with high conservation value. It is restricted to a single catchment in the island state of Tasmania, Australia, where it occurs within moorland pools typically containing crayfish (Ombrastacoides spp.) burrows. Although its moorland habitat has a long history of firing, adverse fire regimes are a potential threat to the species. A large part of its range is subject to planned burning to help manage the detrimental effects of high‐intensity wildfires. The resilience of A. hickmani to low–moderate‐intensity fires was investigated over 13 years using a replicated before‐after‐control‐impact design. The fires resulted in an initial reduction in vegetation cover and surface water and an increase in water temperature. There was no effect of fire on A. hickmani captures 4 months after small‐scale, low‐intensity autumn burns. However, 5 months later, following an unintended larger‐scale, medium‐intensity spring burn, there was an 80–90% reduction in A. hickmani captures and their numbers did not recover until 6–9 years post‐fire. It is not known whether the reduced catch was due to a reduction in the number of A. hickmani or their movement from pools into crayfish burrows. These findings together with evidence of a varied fire history, including high‐intensity wildfires, within their range suggests that A. hickmani and its habitat are resilient to a range of fire frequencies and intensities provided that the fire regime does not degrade or lead to a complete loss of peat. Climate change predictions for warmer and drier summers in western Tasmania will increase the risk of peat loss. Planned burning is likely to be important for the protection of A. hickmani habitat from predicted adverse fire regimes. 相似文献
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