You didn't specify the tissue, neither its animal source. There are, however, some food science/engineering handbooks that you may want to check for possibly useful thermal data, e.g.: George D. Hayes, "Food Engineering Data Handbook", Longman Scientific & Technical (UK) / John Wiley & Sons (USA), 1987; Nuri N. Mohsenin, "Thermal Properties of Food and Agricultural Materials", Gordon & Breach, 1980.

At least for water please see for example the two links (even above 100°C under appropriate pressure conditions):

https://www.engineeringtoolbox.com/water-properties-d_1508.html

(below the table you will find the conversion into W/(mK) and a diagram is near the end of the document)

and

http://onlinelibrary.wiley.com/doi/10.1002/9780470516430.app3/pdf

The formula for k is in the middle of the second page.

I havn't checked the consistency of the two data sets.

Thanks Carlos and Gerhard. I will check the suggested resources.