The Pineal and Reproduction in Fish, Amphibians, and Reptiles

Le résumé fourni par la source

Hydroxyindole-O-methyltransferase (HIOMT) was first shown to be present in the amphibian brain by W. B. Quay. Interestingly, retinal HIOMT activity is substantially greater than pineal HIOMT activity in amphibians, when tissues are collected in the middle of the light phase during the winter months. A role for the amphibian pineal complex in rhythmic phenomena and certain photoperiodic responses seems likely. For example, it has been known for some time that larval amphibians blanch when placed in darkness. The number of studies concerned directly with the elucidation of pineal-gonadal interactions in amphibians is limited. Pinealectomy is without effect on ovarian maturation in larval Alytes obstetricians . Taking the meager data presently available, one would tentatively conclude that the pineal organ is antigonadal among lizards and elasmobranchs, yet progonadal among cyclostomes and anuran amphibians. According to some investigators, a paradox exists in some teleostean fishes where pinealectomy can be either pro- or antigonadal.

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