Development of Malpighian Capsule
Transverse section of a developing Malpighian capsule and tuft from a fetus at about the fourth month. Labels: a, flattened cells growing to form the capsule; b, more rounded cells; continuos with the above, reflected around c, and finally enveloping it; c, mass of embryonic cells which later become developed into blood vessels.
Baker, W. Morrant & Harris, Vincent Dormer Kirkes' Hand-book of Physiology, 13th ed. (Philadelphia: P. Blakiston's Son & Co., 1892) 421