[1] Univ Roma La Sapienza, Dept Med Surg Sci & Biotechnol, I-04100 Latina, Italy
[2] Univ Roma La Sapienza, DAHFMO, Sect Histol & Med Embryol, I-00161 Rome, Italy
[3] Univ Bologna, Dept Expt Pathol, I-40126 Bologna, Italy
[4] CNR, Inst Cellular Biol & Neurobiol, I-00143 Rome, Italy