Fish Pathology
Online ISSN : 1881-7335
Print ISSN : 0388-788X
ISSN-L : 0388-788X
Studies on the Philometrosis of Crucian Carp—II
Some Ecological Observations of Gravid Female
Kenji NAKAJIMASyuzo EGUSA
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JOURNAL FREE ACCESS

1977 Volume 12 Issue 2 Pages 115-120

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Abstract

Gravid females of Philometroides carassii (ISHII, 1931) NARAJIMA et EGUSA, 1977 were found in the caudal fin of the crucian carp, Carassius auratus (LINNé) in the early spring. Their body color originated from the red-colored fluid circulating intermittently in their body cavities and changed from clear red to light pink as eggs developed in the uterus, because the layer of the body fluid became thinner with expansion of the uterus.The pinkish gravid females penetrated the skin with their heads at the base or the posterior end of the caudal fin and moved out slowly into water for themselves. The exposed part of their bodies soon discolored, straightened out and hardened, however, yielding of larvae never occurred so far as their tails stayed in the fin. The process of delivery was observed with three gravid females taken out from hosts. When the worms dipped in water, a kind of pulse possibly due to a contraction of the uterus wall started within a minute from the posterior end to the anterior. At that instant the anterior part of the uterus broke the body wall longitudinally and rushed out into water with the other organs. Almost all larvae were released from the split uterus for several minutes. From the observations that larvae were never lereased so far as the tail of the worm stayed in the fin but released immediately when dipping the whole body in water, we supposed that gravid females might have a receptor of water at their tails.

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© The Japanese Society of Fish Pathology
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