Procercoid

Most of the work on the invasion of the first intermediate host deals with the susceptibility of different species of copepods to infection by coracidia. The evidence points to the conclusion that procercoid specificity is generally euryxenous (i.e. with a broad host spectrum). A striking example is seen with D. latum in which no less than 17 species of copepods are susceptible (59). Some species, however, show a tendency to be stenoxenous (i.e. with a narrow host spectrum), e.g. B. claviceps, with only two copepod species being highly susceptible (189). 

Fig. 8.4. Seasonal prevalence of procercoids of Schistocephalus pungitii and Proteocephaius filicollis in copepods in Lake Koljushkovoe, USSR. (After Sysoev, 1985.)...

It is well recognised that parasite transmission is dependent on many ecological factors and it may be that copepods with a single procercoid may survive better and have larger and more fully differentiated procercoids than hosts with larger infections. Low-level infections may thus be an important adaptive strategy for transmission to the next host 711). 

THE CORACIDIUM/PROCERCOID TRANSFORMATION The ultrastructural changes which take place during the coracidium/ procercoid transformation have been studied largely in the Pseudo-phyllidea 265, 461, 485), but some limited data are available for the... 

A major morphological change which occurs during the coracidium/procercoid transformation is the elongation of the body and the separation of the hooks into a distinct appendage, the cercomer. The nature of this structure and especially its... 

Second larval stage procercoid procercoid growth and development General account... 

Table 8.4. Triaenophorus crassus growth of procercoids in adult males and females of the copepod Cyclops bicuspidatus thomasi. Comparison of mean length and width of 21- to 28-day old procercoids. (Data from Rosen Dick, 1983,)...

Notes Intensity of infection is the number of procercoids per host. N, number of procercoids, with number of hosts in parentheses. 

Fig. 8.8. Bothriocephalus acheilognathi the relationship between age of coracidia ingested by Cyclops viridis and time taken for procercoids to reach maturity. (After Pool, 1985.)...

Fig 8.10. Gland cells in the procercoids of Eubothrium rugosum, Diphyllobothrium latum, and Triaenophorus nodulosus. (Source see Fig. 8.11.)... 

Fig. 8.11. Location of gland cells in plerocercoids of Diphyllobothrium latum, D. dendriticum and Eubothrium rugosum. (Reprinted with permission from International Journal for Parasitology, 12, Kuperman, B. I. Davydov, V. G., The fine structure of glands in oncospheres, procercoids and plerocercoids of Pseudophyllidea (Cestoda), 1982, Pergamon Journals Ltd.)...

Dupont, F. Gabrion, C. (1987). The concept of specificity in the procercoid-copepod system Bothriocephalus claviceps (Cestoda) a parasite of the eel Anguilla anguilla). Parasitological Research, 73 151-8. 

Mackinnon, B. M., Jarecka, L. Burt, M. D. B. (1985). Ultrastructure of the tegument and penetration glands of developing procercoids of Haplobothrium globuliforme Cooper, 1914 (Cestoda Haplobothrioidea). Canadian Journal of Zoology, 63 1470-7. 

Rosen, R. Dick, T. A. (1983). Development and infectivity of the procercoid of Triaenophorus crassus Forel and mortality of the first intermediate host. Canadian Journal of Zoology, 61 2120-28. 

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