The aim of the present study was to examine the influence of TNFR-I mRNA expression on death of granulose cells of antrum follicle and its relation with ovulation rate in sheep. One breed with relatively high ovulation rate (Shall) and another with relatively low ovulation rate (Lori Bakhtiari) were compared regarding Their granulose cells expression of TNFR-I. Ewes fed similar and not using of any method to enhance ovulation rate. Estrus was synchronized. in all animals, with the CIDER (12 day). The granulose cells were collected from antrum follicle 48 hourse after CIDER withdrawal. Total RNA was extracted from cells using an RNeasy mini kit (Qiagen) and then reverse-transcribed to synthesize cDNA. The expression of TNFR-I in both breeds was analyzed by semiquantitative RT-PCR. TNFR-I was not expressed in granulose cells of antrum follicle in sheep. The current study demonstrates that TNFa act as a survival factor or death factor in a follicular stage-dependent manner. antrum follicle atresia is one of the important mechanisms for ovulation rate in female mammals and TNFR-I plays an important role in the control of follicular atresia also ovulation rate in the Shall breed is not controled by major genes reported (booroola, Hana, Inverdale, Cambridge). our results indicate that TNFR-I is not the major factor responsible for shall and lori Bakhtiari differences in ovulation rate. Key word: granulose cell, breed, antral follicle, ovulation rate, atresia
