Louri,

 

Why don't you try microwave accelerated fixation in either formalin or a formalin substitute?  You will need to use a Laboratory Microwave but it would certainly be the answer to your problem.  You can fix the whole placenta in about 45 minutes so that thin sections can be taken or you can fix the specimen in the cassette in about 20 minutes. 

 

Laboratory microwaves are sold by ThermoShandon, TBS, Hacker and Energy Beam Sciences.  I even saw one for sale on HistoNet.

 

Jan Minshew

Histology Consulting Services, Inc.