OESTROGEN LEVELS IN PERIPHERAL BLOOD PLASMA OF THE SPOTTED SKUNK

Abstract

Western forms of the spotted skunk, Spilogale putorius latifrons, breed in late September. The fertilized oocytes undergo cleavage and blastulation but further development is greatly retarded and implantation is deferred for 180 to 200 days. Nidation occurs in mid-April and parturition takes place in mid-May (Mead, 1968). The hormonal control of delayed implantation in this species and other members of the family Mustelidae has long been a perplexing problem. Numerous investigators have suggested that delayed implantation might be the result of inadequate progesterone secretion; however, all attempts to induce nidation by injections of progesterone, have, thus far, failed (Hansson, 1947; Hammond, 1951; Canivenc & Laffargue, 1958; Cochrane & Shackelford, 1962; Wright, 1963). It has been conjectured that the temporary inhibition of nidation results from