The Relation of Lipid Composition to Physio- Logical Activity in the Ovaries of Pregnant and Pseudopregnant Rabbits

In recent years, certain lipids have been found to have an essential role in the vital economy of living cells. The earlier evidence suggesting this relationship was reviewed in 1930 by Bloor, Okey, and Corner (1). Experimental proof of the phenomenon has been based upon two separate procedures. The first method was originally proposed by Mayer and his coworkers, especially Schaeffer and Terroine, and consisted in demonstrating that phospholipids and cholesterol are present in constant amounts in living tissue irrespective of the state of nutrition. These authors ascribed to phospholipids and cholesterol and their relative proportions an essential function in cellular physiology and designated them the t?lSment constant, a conception which was substantiated by the extensive studies of Bloor (2). The second method has been to follow the changes in the various lipid constituents of a tissue over a period of time during which its physiological activity rises and falls. The ovary or the corpus luteum has been frequently selected for this purpose. The corpus luteum has been studied by Eufinger and Bader (3), Momigliano (4), von Mikulicz-Rodecki (5), Kaufmann and Raeth (6), and Bloor, Okey, and Corner (1). The results of these studies have indicated that physiological activity of the corpus luteum is associated with the presence of increasing amounts of phospholipids and usually also free cholesterol; degeneration or retrogression is characterized by falling values for phospholipid and increasing amounts of ester cholesterol and neutral fat. Similar experiments