Cyclic variation of F prostaglandins in the uterine fluids of the cow

A number of reports have indicated that prostaglandins (PGs) of the F series are present in the blood plasma (Bland, Horton & Poyser, 1971; Blatchley, Donovan, Horton & Poyser, 1972; Thorburn, Cox, Currie, Restall & Schneider, 1972; Nancarrow et al., 1973; Peterson, Fairclough, Payne & Smith, 1975; Shemesh & Hansel, 1975) and uterine tissue (Wilson, Cenedella, Butcher & Inskeep, 1972; Levitt, Tobon & Josimovich, 1975; Shemesh & Hansel, 1975) of many species and in the uterine fluid of non-pregnant ewes (Harrison, Heap, Horton & Poyser, 1972). The uterine glands are able to metabolize actively several substances because many components have a higher concentration in the uterine fluid than in the blood (Lamothe & Guay, 1970; Schultz, Fahning & Graham, 1971). Shemesh & Hansel (1975) gave the values of PGF in the bovine endometrium but the PGFcontent of the uterine fluid of the cow has not been investigated throughout the oestrous cycle.