2011 YÜksek lisans tez özetleri

Alteratıons In The Pronephros And Mesonephros Of Frog (Rana Ridibunda) Larva Durıng Metamorphosıs

Amphibian metamorphosis includes three developmental periods: premetamorphosis, prometamorphosis and climax, respectively. There are two types of kidney in amphibians: pronephros and mesonephros. At the end of metamorphosis, pronephros completely degenerates and developed mesonephros takes all the responsibility of kidney function alone.

The aim of this study is to determine the structure of Rana ridibunda larval kidneys and histological changes during this process and programmed cell death type in degenerating pronephric kidney and developing mesonephric kidney. Moreover, the study explores changes of cadherin expression in this process.

In our study, we used animals at the stages of three main periods of metamorphosis: premetamorphosis, prometamorphosis and climax. Sections of pronephric and mesonephric kidney tissues were stained with hematoxylin-eosin, Masson trichrome, periodic acid Schiff dyes to investigate their histologic structure and changes. Immunohistochemical methods were used to determine the programmed cell death type and presence of cadherin molecule, which is a cell adhesion molecule, with the changes in its expression.

We determined histologically degenerating tubules and lipofuscin pigments appeared in Rana ridibunda pronephric kidney during metamorphosis. We observed increase in the size of mesonephric kidney and the formation of new tubule. Furthermore, we detected that some proximal tubules of mesonephric kidney had cytoplasm with vacuoles and granules. We observed immunohistochemically caspase-3, which is a marker of caspase dependent apoptosis, and LC3, which is a marker of autophagy, existing in the programmed cell death which occurs in degenerating pronephric kidney and some proximal tubules of mesonephric kidney. Additionally, we determined that cadherin expression decreased during the metamorphosis in degenerating pronephric kidney and some proximal tubules of mesonephric kidney.

The programmed cell death, which occurs in amphibian (Rana ridibunda) larval kidney, is different from known apoptosis or autophagy. Most probably, caspase-3 and autophagy work together in the new type of programmed cell death. Cadherin expression decreased in the pronephric kidney degeneration and dying proximal tubules of mesonephric kidney during metamorphosis. Amphibian larval kidneys are two new tissues for understanding the programmed cell death mechanism.