Duration and method of tissue storage alters placental morphology - implications for clinical and research practice.

We assessed whether placental morphology is affected by placental storage before fixation. Fresh tissue from uncomplicated pregnancies (n = 10) was fixed immediately and further samples were stored dry, in PBS or culture medium for 24, 48 or 72 h at 4 °C. Placental morphology quantified using image analysis software found no difference in syncytial nuclear aggregates, cytokeratin 7, CD45 or Ki67 immunostaining irrespective of duration or mode of storage. The number of blood vessels per villus (CD31) was reduced in all conditions after 72 h (p <0.05). Distal villous hypoplasia increased after 72 h (p <0.05). Ideally, storage time should be minimised to ≤48 h prior to morphological or qualitative analysis.