Development of the Gonads in Parasitic and Non-Parasitic Lampreys

Abstract

IN relation to the origin of the non-parasitic brook lampreys the view now generally accepted is that these forms have arisen from closely related parasitic species by virtue of a precocious development of the gonads^1–3. As a result, sexual maturity is attained so soon after metamorphosis that the migratory, parasitic phase has been eliminated from the life-cycle. The recent discovery of neotenous female ammocœtes of the Italian brook lamprey, L. zanandreai Vladykov⁴, tends to support the view that brook lampreys show an inherent tendency towards pædomorphosis.