Studies on follicular growth in the immature rat and hamster: Effect of a single injection of gonadotropin or estrogen on the rate of 3H-thymidine incorporation into ovarian DNA in vitro

C. S. Sheela Rani, N. R. Moudgal

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Initiation of follicular growth by specific hormonal stimuli in ovaries of immature rats and hamsters was studied by determining the rate of incorporation of 3H-thymidine into ovarian DNA in vitro. Incorporation was considered as an index of DNA synthesis and cell multiplication. A single injection of pregnant mare serum gonadotropin could thus maximally stimulate by 18 hr 3H-thymidine incorporation into DNA of the ovary of immature hamsters. Neutralization of pregnant mare serum gonadotropin by an antiserum to ovine follicle stimulating hormone only during the initial 8-10 hr and not later could inhibit the increase in 3H-thymidine incorporation in vitro observed at 18 hr, suggesting that the continued presence of gonadotropin stimulus was not necessary for this response. The other indices of follicular growth monitored such as ovarian weight, serum estradiol and uterine weight showed discernible increase at periods only after the above initial event. A single injection of estrogen (diethyl stilbesterol or estradiol-l7β) could similarly cause 18 hr later, a stimulation in the rate of incorporation of 3H-thymidine into DNA in vitro in ovaries of immature rats. The presence of endogenous gonadotropins, however, was obligatory for observing this response to estrogen. Evidence in support of the above was two-fold: (i) administration of antiserum to follicle stimulating hormone or luteinizing hormone along with estrogen completely inhibited the increase in 3H-thymidine incorporation into ovarian DNA in vitro; (ii) a radioimmunological measurement revealed following estrogen treatment, the presence of a higher concentration of endogenous follicle stimulating hormone in the ovary. Finally, administration of varying doses of ovine follicle stimulating hormone along with a constant dose of estrogen to immature rats produced a dose-dependent increment in the incorporation of 3H-thymidine into ovarian DNA in vitro. These observations suggested the potentiality of this system for developing a sensitive bioassay for follicle stimulating hormone.

Original languageEnglish (US)
Pages (from-to)41-51
Number of pages11
JournalProceedings of the Indian Academy of Sciences - Section B, Experimental Biology
Issue number1
StatePublished - Jan 1 1978
Externally publishedYes



  • H-thymidine incorporation into ovarian DNA
  • Pregnant mare serum gonadotropin
  • bioassay for follicle stimulating hormone
  • estrogen
  • follicle stimulating hormone
  • gonadotropin antisera
  • luteinizing hormone
  • ovarian follicular growth

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

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