THE EFFECT OF THIOUREA, ADMINISTERED BY IMMERSION OF THE MATERNAL ORGANISM, ON THE EMBRYOS OF LEBISTES RETICULATUS, WITH NOTES ON THE ADULT GONADAL CHANGES

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Abstract
Thiourea was used to study the possible transfer of material from the parent to the embryo Lebistes reticulatus. Adult fish that had presented 3 broods at 28 - 31 day intervals were utilized in the investigation. Groups of experimental animals were maintained in a 0.04% solution of the anti-thyroid agent starting with the following times between their 3rd and 4th brood: 1 day, 1 week, 2 weeks and 3 weeks after the presentation of the 3rd brood. Control animals were maintained in water without thiourea. All animals were sacrificed either during the presentation of the 4th brood or within 10 hours of delivery of the young. The thyroids and gonads were studied histologically. Thyroid hyper-plasia was seen in all treated adults and their young. Thyroid cell height was increased, the degree of change increased with the time of exposure. The gill region, heart, kidneys, spleen and intestines of young obtained from treated adults showed the presence of thyroid tissue. Adults treated for the longer intervals also showed thyroid metastasis. This was not observed in any of the control adults or . their young. A decrease in gonadal activity was evident in the adults treated for the longer intervals. The broods presented were smaller in number than either of their previous broods. The ovaries of these fish contained fewer than the normal number of maturing ova. The hyperplasia and metastasis of the thyroid tissue of the young of the treated fish is considered evidence for the passage of material from the parent to the developing young in the teleost studied.