Abstract
MUCH confusion still exists in generalized accounts of life-histories of parasitic platyhelminthes concerning the position of the egg at the time of its maturation divisions and therefore about the exact time of fertilization. Indeed, it has been suggested1 that normal gametogenesis does not occur in many cestodes of the Cyclophyllidea, Tetraphyllidea and Trypanorhyncha. In a number of digenetic trematodes, on the other hand, it has been carefully shown by various workers, notably Chen2, Rees3, Stephenson4 and Willmott5, that meiosis in the ovum is normal and occurs in that part of the uterus immediately beyond the central chamber of Mehlis's gland. The ova move into the uterus at this point surrounded by yolk cells and begin maturation divisions at once while the shell is being laid down around the egg complex, which comprises one ovum, yolk cells and spermatozoa.
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References
Young, R. T., Arch. Zellf., 117, 419 (1923).
Chen, P. D., Trans. Amer. Micro. Soc., 56, 208 (1937).
Rees, G., Parasitol., 31, 417 (1939).
Stephenson, W., Parasitol., 38, 128 (1947).
Willmott, S., J. Helminth., 24, 1 (1950).
Motomura, I., Annot. Zool. Japan, 12, 109 (1929).
Rawson, D. (unpublished MS.).
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RAWSON, D. Maturation Divisions of the Ova in the Pseudophyllidean Cestode, Eubothrium crassum (Bloch). Nature 176, 167 (1955). https://doi.org/10.1038/176167a0
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DOI: https://doi.org/10.1038/176167a0
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