Endocrinology of the lampreys

摘要: Abstract The ammocoetes larvae of the modern Petromyzontiformes are slowly growing filter feeders, and imagines rapidly macrophagous fish parasites. demonstrate prototypal metabolism Silurian Devonian Agnatha; show typical Gnathostomata. metamorphosis repeats period evolution in which Gnathostomata arose from Agnatha. graduation differentiation is also expressed endocrine system. These principal conditions varied throughout environments different phases life cycle Petromyzontiformes. After a long larval freshwater young lampreys migrate toward sea (catadromous migration). Here they start parasitic feeding period. some time cease irreversibly to feed gather for spawning migration. die. During after following organs increased characteristically: adenohypophysis; endostyle → thyroid; medulla cortex cells scattered along kidneys. Only few changes visible hypothalamoneurophypophyseal system islets Langerhans. Thymus parathyroids absent Our knowledge based predominantly on morphological classical experimental methods. Biochemical pharmacological studies as yet rare. Nothing known marine parasitic-feeding hormones have been identified lampreys: vasotocin, thyroxine, triiodothyronine, insulin. Vasotocin affects only sodium metabolism; no antidiuretic action could be demonstrated. presence steroids probable. By investigations results may obtained showing primary function vertebrate hormones.