A comparative histological study of osmotic regulator organs in matured and pre-mature Caspiomyzon wagneri migrating to Shiroud River

Migrant Caspian lamprey (Caspiomyzon wagneri) are migrating to spawn into upstream of southern watersheds as matured and pre-mature during spring and fall. Osmotic regulator organs (gill and kidney) play an important role in this migration. Lampreys were caught by hand (n:24; number in group:3) in spring (April) and fall (October), from mouth of Shiroud River at night. External morphological characteristics and sexual organs (testes and ovaries) were investigated. For histological analysis, small pieces of the kidney and ovary were fixed in 10% formalin, embedded in paraffin, sectioned with microtome and stained with hematoxylin-eosin. Columnar or flask-shaped cells of chloride each with a rounded, basal or central nucleus were found in the inter platelet regions of the gill in the spring migrants. These cells also were covered by a superficial layer of pavement cells with a little Change in fall. The number of chloride cells of gill (among the first five of the lamellaes in one filament gill) was increased in matured fish compared to pre-mature fish but was not significantly different. A large number of lobed glomeruliform the elongate glomus. The total length of all glomus (posterior part of kidney) were significantly different in matured compared to pre-mature fish in both seasons.