마우스에 있어서의 견회충(犬蛔蟲) 유충의 태내감염(胎內感染)에 관한 연구

Abstract

[한글]

Experimental Study on the Transplacental Transmission of Toxocara canis Larvae in

Mice

Hong-Ki Min, M.D.

Department of Medical Science The Graduate School, Yonsei University

(Director ; Professor Keun-Tae Lee)

Since the discovery of Schistosoma japonicum in the fetus of a dog by Fujinami

and Nakamura(1911). the prenatal infection with parasitic worms has been received

considerable attention. Fellowing this report, a number of the prenatal

helminthiasis was reported in the past.

The prenatal infestations with the dog ascarid, Toxocara canis (Fulleborn, 1921 ;

Shillinger and Cram, 1923: Augustine, 1927) and with the dog hookworm, Ancytostoma

caninum(Adler and Clark, 1922: Foster, 1932; Yutuc, 1949) were demonstrated in dogs

experimentally. In observations using mice (Webster, 1956; Pike, 1960: Oshima,

1961b) as an unnatural host, the results on the appearance of Toxecara cant's

larvae in the fetus from the mothers infected during pregnancy were different among

each other. In addition to these investigations, there were also several

observational evidences in case of human (Narabayashi, 1914: Beaver et al., 1952:

Bisseru et al., 1966) to indicate strongly the possibility of the intrauterine

infestation to the fetus with the parasitic worm, as well as in case of animal.

On the basis of the observations described above, it seems reasonably clear that

the infestations of these parasites acquired by the mother prior to or during

pregnancy may have been responsible for the transplacental transmission to the

fetus, and that considerable differences were noted in the migratory behaviour of

Toxocara canis larvae in normal mice and those in the pregnant mice.

The present study was designed to elucidate the migratory behaviour of the larvae

from maternal side to fetal side. For the purpose, the experiment was carried on

with pregnant and non-pregnant animals setting up various stages.

As an experimental animal, female albino-mice, weighing approximately 21.0 gm.

were used in the present study. Egga of canine ascarid were obtained from the feces

of 3 or 4 months old puppies. and incubated in 0.5% formalin at room temperature

for periods ranging from 30 to 35 days. Embryonated eggs used for infection were

net older than 7 weeks of cultivation, and 1,000 of eggs in 0.5 ml. suspension were

given orally to 54 of normal mice, 45 of mice prior to gestation and 35 of pregnant

mice according to the experimental schedule.

To count the larvae recovered from the tissues, Baermann apparatus was employed.

All the tissues and organs were split into two parts, and the one half was used for

counting of the number of the larva and the other was used for microscopic

findings.

The results in the present study are summarized as follows:

1. No larva was found in the uterus of non-pregnant mice during eight weeks

observation.

2. Some larvae were found in the uterus of pregnant mice infected at a week prior

to gestation, but not in the placenta and the fetus. The mice infected more than

two weeks before gestation showed no larva in these tissues.

3. In the groups infected during pregnancy, the second-stage larvae were found in

the placenta from the 9th day and in the fetus from the 11th day of pregnancy. The

larvae were recovered from the uterus, the placenta and the fetus, but were more in

number among the groups infected at the middle stage of pregnancy than in the

groups of early stage of pregnancy.

4. By microsections, some larvae were detected in bath maternal sinusoidal spaces

and fetal capillary vessels in the placenta. Remarkable dilatation of the involved

spaces was demonstrated, and it seemed to be influenced due to liberation of a

certain biologically active substance from the larvae. Mechanical damages of the

wall (trophoblastic and endothelial layers) of the labyrinth due to penetration by

the larvae were demonstrated in the sections. Fine tissue debris were also

sometimes seen in the spaces but no definite inflammatory cell response was

obsereved surround-ing the spaces in which the larva was present.

The results suggest that the stages of the placental formation and maturity are

closely related to the migratory behaviour of Toxocara canis larvae in pregnant

mice.

[영문]

Since the discovery of Schistosoma japonicum in the fetus of a dog by Fujinami and Nakamura(1911). the prenatal infection with parasitic worms has been received considerable attention. Fellowing this report, a number of the prenatal helminthiasis was reported in the past.

The prenatal infestations with the dog ascarid, Toxocara canis (Fulleborn, 1921 ; Shillinger and Cram, 1923: Augustine, 1927) and with the dog hookworm, Ancytostoma caninum(Adler and Clark, 1922: Foster, 1932; Yutuc, 1949) were demonstrated in dogs

experimentally. In observations using mice (Webster, 1956; Pike, 1960: Oshima, 1961b) as an unnatural host, the results on the appearance of Toxecara cant's larvae in the fetus from the mothers infected during pregnancy were different among each other. In addition to these investigations, there were also several observational evidences in case of human (Narabayashi, 1914: Beaver et al., 1952: Bisseru et al., 1966) to indicate strongly the possibility of the intrauterine infestation to the fetus with the parasitic worm, as well as in case of animal.

On the basis of the observations described above, it seems reasonably clear that the infestations of these parasites acquired by the mother prior to or during pregnancy may have been responsible for the transplacental transmission to the fetus, and that considerable differences were noted in the migratory behaviour of Toxocara canis larvae in normal mice and those in the pregnant mice.

The present study was designed to elucidate the migratory behaviour of the larvae from maternal side to fetal side. For the purpose, the experiment was carried on with pregnant and non-pregnant animals setting up various stages.

As an experimental animal, female albino-mice, weighing approximately 21.0 gm. were used in the present study. Egga of canine ascarid were obtained from the feces of 3 or 4 months old puppies. and incubated in 0.5% formalin at room temperature

for periods ranging from 30 to 35 days. Embryonated eggs used for infection were net older than 7 weeks of cultivation, and 1,000 of eggs in 0.5 ml. suspension were given orally to 54 of normal mice, 45 of mice prior to gestation and 35 of pregnant mice according to the experimental schedule.

To count the larvae recovered from the tissues, Baermann apparatus was employed. All the tissues and organs were split into two parts, and the one half was used for counting of the number of the larva and the other was used for microscopic

findings.

The results in the present study are summarized as follows:

1. No larva was found in the uterus of non-pregnant mice during eight weeks observation.

2. Some larvae were found in the uterus of pregnant mice infected at a week prior to gestation, but not in the placenta and the fetus. The mice infected more than two weeks before gestation showed no larva in these tissues.

3. In the groups infected during pregnancy, the second-stage larvae were found in the placenta from the 9th day and in the fetus from the 11th day of pregnancy. The larvae were recovered from the uterus, the placenta and the fetus, but were more in

number among the groups infected at the middle stage of pregnancy than in the groups of early stage of pregnancy.

4. By microsections, some larvae were detected in bath maternal sinusoidal spaces and fetal capillary vessels in the placenta. Remarkable dilatation of the involved spaces was demonstrated, and it seemed to be influenced due to liberation of a certain biologically active substance from the larvae. Mechanical damages of the wall (trophoblastic and endothelial layers) of the labyrinth due to penetration by the larvae were demonstrated in the sections. Fine tissue debris were also sometimes seen in the spaces but no definite inflammatory cell response was obsereved surround-ing the spaces in which the larva was present.

The results suggest that the stages of the placental formation and maturity are closely related to the migratory behaviour of Toxocara canis larvae in pregnant mice.