Aporocotyle simplex (Odhner, 1900)
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publication ID |
https://doi.org/ 10.1016/j.jcz.2023.05.003 |
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DOI |
https://doi.org/10.5281/zenodo.10375363 |
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persistent identifier |
https://treatment.plazi.org/id/03CA3B6F-F333-FFC9-FF82-D08BFBEBC01A |
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treatment provided by |
Felipe |
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scientific name |
Aporocotyle simplex |
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3.4. Gastrodermis of A. simplex View in CoL
Along its entire length, the syncytial epithelial lining of the caecum is composed of a morphologically uniform, syncytial layer, possessing considerable variation in the thickness of the epithelial lining from 0.5 to 15.0 μm, without marked differences between its anterior and posterior regions ( Fig. 4A and B View Fig ). Most of the luminal volume of the caecum is filled with moderately dense amorphous finely dispersed material ( Fig. 4A, B, I, K View Fig ). In addition, there are both dark inclusions of different shape and different kinds of residual bodies within the caecal lumen ( Fig. 4A and K View Fig ). The gastrodermal luminal surface is increased by numerous thin, flexible lamellae, which project a short distance into the lumen and range in length from 0.9 to 2.5 μm ( Fig. 4B and K View Fig ). The basal plasma membrane of the gastrodermal syncytial lining is thrown into numerous basal invaginations, which may be confined to the lower haft of the gastrodermis, but may extend to the luminal membrane ( Fig. 4C View Fig ). The gastrodermal lining is underlain by a thin basal lamina and thicker layer of fibrous extracellular matrix ( Fig. 4B View Fig ). Thin fibres of circular muscles are embedded in the surrounding extracellular matrix ( Fig. 4C and D View Fig ). The syncytial cytoplasm contains elongated oval or irregularly shaped nuclei with dense patches of heterochromatin, which usually occupy the central or basal positions within the epithelial lining ( Fig. 4A and B View Fig ). The dense cytoplasmic matrix of the gastrodermis contains cisternae of granular endoplasmic reticulum, which are usually located in the proximity of the nuclear areas ( Fig. 4B and H View Fig ). Golgi bodies give rise to ovoid membrane-bound rounded vesicles ranging from 0.1 to 0.3 μm in diameter, which may occur throughout the syncytial layer ( Fig. 4B, G, H View Fig , insert, K). These vesicles contain an agglomeration of finely dispersed, flocculent and moderately dense material ( Fig. 4G and H View Fig insert, I). Regularly arranged tubular arrays are scattered throughout the gastrodermal syncytial lining ( Fig. 4E, H, I, J View Fig ). Occasionally, multivesiculate bodies (about 0.4 μm in diameter) are dispersed in the upper portion of the syncytial cytoplasm ( Fig. 4G View Fig ). Different kinds of residual bodies are scattered throughout the cytoplasm ( Fig. 4C D, F, H, I, J View Fig ). Some bodies show a combination of alternate electron-dense glandular and moderately dense finely dispersed material ( Fig. 4F, H, I, J View Fig ). The membrane-bound Golgi vesicles appear to fuse with residual bodies ( Fig. 4F and I View Fig ). Occasionally, there are large residual bodies (from 2.0 to 2.6 μm in diameter) containing heterogeneous, flocculent and moderately dense material, within which are scattered clumps of electron dense material ( Fig. 4C and D View Fig ). In Fig. 4H View Fig three stages of development of such bodies may be observed in the gastrodermal cytoplasm. The nascent body (nb) is about 0.4 μm in diameter containing moderately dense flocculent, loosely packed material with a few pinpoint clumps of dense material and, a short way off it, the network of tubular structures and Golgi vesicles ( Fig. 4H View Fig ). As such bodies develop, their diameter begins to increase from 0.9 μm (dlb1) to 1.5 μm (dlb2) and the amount of both flocculent moderately dense and clumpy dense material increases ( Fig. 4H View Fig ). In the worms studied, along the entire length of the caecum there are areas in a secretory-absorptive phase possessing a highly vacuolated luminal surface, where the lamellae may be of various configurations and appear to be recurved to form loops ( Fig. 4B, I, J View Fig ). In such gastrodermal areas the percentage of the granular endoplasmic reticulum and the Golgi complexes increases and the amount of Golgi vesicles begins to increase in the gastrodermal cytoplasm ( Fig. 4B and K View Fig ). The numerous vesicular-like surface depressions are filled with trapped material from the gastrodermal lumen, demonstrating the subsequent stages of their endocytosis into the gastrodermis ( Fig. 4I–K View Fig ). Also, between flattened lamellae an agglomeration of residual material is entrapped ( Fig. 4I and J View Fig ).
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