This study was carried out at the Institute of Biotechnology, University of Helsinki, and the Hospital for Children and Adolescents during 1994- 1998.

I wish to express my gratitude to the head of the Institute, Professor Mart Saarma, not only for the collaboration but also for his support and warm interest in my work. He has always been willing to help and share his time and advice in various situations.

I want to thank my supervisor, docent Hannu Sariola for his eternal optimism and vast knowledge of development and pathology and all the different aspects of scientific work. I have learned a lot from him and enjoyed our discussions about science as well as life, as we know it.

The Hospital of Children and Adolescents has always been very helpful. I am grateful to Professor Jaakko Perheentupa for the encouraging atmosphere for science in the clinic. Professor Juhani Rapola, my clinical supervisor, I thank for his help and advice, especially in pediatric pathology.

Professor Heikki Rauvala and Docent Lauri Aaltonen have given their time to pre-examine and improve the manuscript and I am grateful for their effort.

I want to thank my numerous collaborators outside the Institute: Prof Leena Peltonen, Dr. Paulina Paavola, Prof. Aarno Palotie, Dr. Nina Horelli-Kuitunen, Dr. Juha Rinne and Docent Risto Rintala have been important collaborators and it has been a pleasure to work with them.

The whole personnel of the Institute of Biotechnology is acknowledged for the stimulating environment as well as direct help in practical issues whenever needed. Special thanks go to the DNA synthesis and sequencing laboratory, headed by Lars Paulin.
 
 

The Developmental Biology Program of the Institute of Biotechnology led by our marvelous professor Irma Thesleff has been a good place to work. I want to thank all the members of the #development for the positive feedback and warm atmosphere. I have enjoyed the diversity of our group, both in science and social life, and I think that we make a dynamic team, also outside the sähly court.

Especially I wish to thank the members of the kidney group: Hannu, Kirsi, Anne, Marjo, Juan, Tiina, Mervi, Mika, Maxim, Illar, Jukka, Birgitta, Lilli and others for the every day life in the lab. Working with you is never boring, and maybe that is the clue to keep on going. The people in Mart’s groups have also been very close to me and Petro, Tero, Ülo, Kristiina, Maria, Urmas, Eila, Mait, Mati, Jukka, Antti, and others I thank for all the help and nice time in the former labs in Karvaamokuja and in the C-tower. Luckily, the friendship lasts longer than the shared reagents when working side by side.

Finally, I would like to thank my family and friends. My late mother was always proud of my work and I owe her a lot. I want to thank all my relatives and friends for their support, but especially my father for the discussions and advice. It has been a pleasure and a privilege to work literally under the eyes of the previous generation. However, my deepest gratitude goes to my wife Anu, not for the countless scientific discussions or help in the techniques but for sharing the most valuable things in life with me and our daughters Alli and Linnea.

This work has been financially supported by the Foundation for Pediatric Research, The Foundation for Gastrointestinal Research, Academy of Finland, University of Helsinki, HUCH research funding, Sigrid Jusélius Foundation and EU Biomed II.

Helsinki, beautiful May 1998