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  • Title: Examination of the role of FSH in periovulatory events in the hamster.
    Author: Rani CS, Moudgal NR.
    Journal: J Reprod Fertil; 1977 May; 50(1):37-45. PubMed ID: 864651.
    Abstract:
    The need for endogenous FSH in the periovulatory events such as oocyte maturation, ovulation, luteinization, maintenance of luteal function and follicular maturation was examined in the cyclic hamster. A specific antiserum to ovine FSH, shown to be free of antibodies to LH and to cross-react with FSH of the hamster, was used to neutralize endogenous FHS at various times. Administration of this antiserum during pro-oestrus did not affect oocyte maturation and ovulation, as judged by the normality of the ova to undergo fertilization and normal implantation. It also had no effect on the process of luteinization or on the maintenance of luteal function as indicated by the normal levels of plasma and luteal progesterone during pro-oestrus and oestrus during the cycle and in pregnancy. All these processes were, however, disrupted by administration of an antiserum to ovine LH, thereby demonstrating their dependence on endogenous LH. Although FSH antiserum given at pro-oestrus did not prevent the imminent ovulation, it blocked the ovulation occurring at oestrus of the next cycle. This antiserum was effective in preventing the ensuing ovulation when given at any other time of the cycle until the morning of pro-oestrus. It is concluded that, in the hamster, high levels of FSH during pro-oestrus and oestrus are required for initiating maturation of a new set of follicles which are dependent on the trophic support of FSH throughout the cycle until the morning of pro-oestrus. Such follicles then appear to need only LH for subsequent ovulatory and associated processes. Antisera for follicle stimulating hormone (FSH) were used in examining the role of FSH in the periovulatory events in the hamster. Antisera to ovine FSH were shown to be free of antibodies to luteinizing hormone (LH) and were able to cross-react with FSH in the hamster in order to neutralize it. Proestrous cyclic hamsters were given either .2 ml normal monkey serum (NMS), .1 ml FSH antiserum, or .2 ml LH antiserum. Animals were killed on the next day and their oviducts examined for the presence of ova. Luteinization was studied in a similar manner. Blood samples were taken for analysis of progesterone content 4 hours after injection and again 24 hours later. The completion of the follicular maturation process was assessed by checking ovulation at the next cycle. FSH antiserum was unable to block ovulation; the animals treated with FSH antiserum had normal ova with fertilization, and normal implantation was reported. It was also without effect on luteinization or on the maintenance of luteal function as indicated by normal levels of plasma progesterone and luteal progesterone. However, LH able to completely block ovulation. While FSH in proestrus was unable to prevent the imminent ovulation, it blocked ovulation in the estrus of the next cycle and was effective at preventing ensuing ovulation given at any other time of the cycle other than the morning of proestrus. These results indicate that FSH is needed during the proestrus and estrus for initiating maturation of a new set of follicles which are dependent on FSH until the morning of proestrus.
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