Blood

After clotting of blood, a water like fluid remains, it is called serum. Fibrinogen protein and other clotting factors are absent in this serum.

Lymph has only white blood cells (WBCs) so the colour of lymph is white (RBCs are not present in lymph). While blood has RBCs, WBCs, blood plasma and platelets.

When the mother is and the foetus is having , the immune cells of the mother will produce the antibodies against the blood cells of the foetus.
This will lead to destruction of the blood cells in the foetus when the antibodies migrate through the placenta and enter the foetal system. This causes the death of the foetus and the condition is known as erythroblastosis foetalis.