CBSE Class 10 Answered

The hydrostatic pressure inside the blood capillaries is greater than that in the tissues, pushing fluid out. The fluid that leaks out into the interstices among the cells is a little of the watery part of the blood plasma, with all the substances it contains except for the larger proteins. Also a very small fraction of the plasma proteins escape from blood capillaries in the tissues. Hence lymph contains less proteins than blood plasma.

Lymph contains relatively less of the larger proteins compared to plasma suggesting that molecular size is important in lymph filtration.