EXTENSION OF EMPLOYMENT AGREEMENT DATE: March 31, 1999 PARTIES: Techne Corporation, a Minnesota corporation 614 McKinley Place N.E. Minneapolis, Minnesota 55413 Thomas C. Detwiler, Ph.D. 1601 Northrap Lane Minneapolis, Minnesota 55403 AGREEMENTS: The parties hereby agree that the termination date of the Employment Agreement between them dated December 28, 1995 and originally for the period July 1, 1995 through June 30, 1998 is extended to June 30, 2001. All other provision of such Employment Agreement shall remain in full force and effect. TECHNE CORPORATION By /s/ Thomas E. Oland ------------------------------- Thomas E. Oland, President "Company" /s/ Thomas C. Detwiler ------------------------------- Thomas C. Detwiler, Ph.D. "Employee"