• John W. Everett
Part of the Monographs on Endocrinology book series (ENDOCRINOLOGY, volume 32)


Embryologists searching for early stages of mammalian development were responsible for the first basic knowledge of circumstances attending ovulation. The relationship was recognized in a general way between behavioral estrus, on the one hand, and ovulation, corpus-luteum formation and pregnancy on the other. Aside from cats and rabbits, in which ovulation is provoked by copulation, spontaneous ovulation was evident in familiar species. Rhythmic changes were known to occur in the reproduction tracts of spontaneous ovulators, but the close relationship between such changes and the time of ovulation remained a mystery until the vaginal smear technique was devised for the guinea pig (Stockard and Papanicolaou 1917), the rat (Long and Evans 1922) and mouse (Allen 1922). The following excerpt from the classical monograph of Long and Evans is noteworthy:

“By the fortunate discovery that in the guinea pig [cyclic mucosal changes in the reproductive tract] are accompanied by dehiscence of epithelial cells so that at times the vagina has a characteristic cell content, it has been possible for Stockard and Papanicolaou to show us that we may discover with ease in the living animal the exact occurrence and progress of these cycles. When it has been proved, as Stockard and Papanicolaou have done for the guinea pig, and as we have been able to do with exactitude for the rat, that these cycles are correlated with the rhythmic discharge of ova from the ovary, it will be seen that we now have in our hands for the first time an accurate method for the detection of ovarian function in experimental animals. This fact promises important consequences, for it enables us to investigate disturbances of ovarian function which may be experimentally produced.”

Copyright information

© Springer-Verlag Berlin Heidelberg 1989

Authors and Affiliations

  • John W. Everett
    • 1
  1. 1.Department of NeurobiologyDuke University Medical CenterDurhamUSA

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