Table 2 Placental Collection

1. Placenta

Sites at the periphery of four lobules, free of visible infarction, calcification, haematoma or damage are identified. 1–2 mm of tissue is removed from the maternal surface (basal plate) and discarded. A "grape size" sample of placental tissue is then obtained from each site and washed repeatedly in chilled phosphate buffered saline. The following samples are obtained from each 'grape':

i. RNA: Four 5 mg pieces placed in RNA later, (Applied Biosystems, Warrington, UK), and stored at -80°C.

ii. DNA & protein: Four 50 mg pieces, frozen in liquid nitrogen and stored at -80°C.

iii. Histology: A "pea-sized" sample is fixed in 3 ml of formalin (24 hours at 4°C) and embedded in paraffin wax.

2. Placental membranes

A 2 × 2 cm portion of the membranes is obtained and fixed in formalin as above.

3. Cord blood

A 10 ml anti-coagulated (EDTA/citrate) sample is obtained. Peripheral blood mononuclear cells are isolated and stored in liquid nitrogen.

4. Umbilical Cord

The following samples are obtained

i. DNA & protein: Two 100 mg pieces of cord, frozen at -80°C.

ii. Histology: One 5 mm transverse section of cord is fixed in formalin as above.

Basic level collection

Placenta is stored in a fridge and sampled within 24 hours of delivery.

1. Placenta

Four 'grape size' samples are obtained and washed as described above. From each 'grape' sample, the following are obtained:

i. DNA & protein: Four 50 mg pieces, frozen at -80°C.

ii. Histology: A "pea-sized" sample is fixed in 3 ml of formalin as above.

2. Placental membranes

A 2 × 2 cm portion of the membranes is obtained and fixed in formalin as above.

3. Umbilical cord

The following samples are obtained

i. DNA & protein: Two 100 mg pieces of cord, frozen at -80°C.

ii. Histology: One 5 mm transverse section of cord is fixed in formalin as above.