Secretion And Identification Of Cumulus Expansion-inhibiting Factor (ceif) In Goat Follicles

As a consequence of the endogenous gonadotropin surge in the preovulatory period, the compacted cumulus cells around the oocyte expand visibly. This phenomenon is named as cumulus expansion or mucification. Cumulus expansion plays an important role on ovulation and fertilization. Pioneering work suggested that follicular fluid contains cumulus expansion-inhibiting factor(CEIF). The objective of this paper was to study the secretion of cumulus expansion-inhibiting factor (CEIF) in goat follicles. We used an interspecies testing system and mouse oocytectomized complexes (OOXs) to test CEEF activity in goat middle follicular fluid, large follicular fluid and CEEF produced by somatic cells in the middle follicles. We used mouse cumulus-oocyte complexs (COCs) to test CEIF activity in goat middle follicular fluid, large follicular fluid and CEIF produced by somatic cells in the middle follicles, and tried to find out that what is CEIF. We also studied the effect of sulfated glycosaminoglycan on cumulus expansion of mouse COCs and goat COCs.The results showed that:1.When cultured in medium containing 10% and 50% of FF from 2-4 mm follicles, 60% and 55% of the mouse OOXs showed cumulus expansion, respectively, which suggested that middle follicular fluid contained CEEF activity.When cultured in 100% FF from 2-4mm follicles, the FF inhibited cumulus expansion of mouse COCs, which suggested that middle follicular fluid contained CEIF activity.2.The FF from 5-6 mm follicles did not support cumulus expansion of mouse OOXs at any of the concentrations tested, which suggested that the follicular fluid from 5-6 mm follicles didn't contain CEEF activity. The FF from 5-6 mm follicles did not inhibit cumulus expansion of mouse COCs at any of the concentrations tested, which suggested that the follicular fluid from 5-6mm follicles didn't contain CEIF activity.3.The FF from 5-7 mm follicles after cloprostenol injection did not support cumulus expansion of mouse OOXs at any of the concentrations tested, which suggested that the follicular fluid from 5-7 mm follicles after cloprostenol injection didn't contain CEEF activity. The FF from 5-7 mm follicles after cloprostenol injection did not inhibit cumulus expansion of mouse COCs at any of the concentrations tested, which suggested that the follicular fluid 5-7 mm follicles after cloprostenol injection didn't contain CEIF activity.4.The FF from 5-7 mm follicles after HCG injection support cumulus expansion of mouse OOXs at any of the concentrations tested, which suggested that the follicular fluid from 5-7 mm follicles after HCG injection contained CEEF activity. The FF from 5-7 mm follicles after HCG injection did not inhibit cumulus expansion of mouse COCs at any of the concentrations tested, which suggested that the follicular fluid 5-7 mm follicles after HCG injection didn't contain CEIF activity.5.Cumulus cells and mural granulosa cells from 2-4mm follicles secreted CEEF, didn't secrete CEIF. However, When cultured in medium conditioned with the monolayer prepared from thecal cells in the presence of eCG and cumulus expansion, only 20% of the mouse COCs showed cumulus expansion which suggested thecal cells secreted CEEF, also secreted CEIF. The CEIF in middle follicles is mainly secreted by thecal cells.6.The concentration of S-GAG in follicular fluid from middle follicles, large follicles, 5-7mm follicles after PG and HCG injection was 1.2 mg/ml,0.91 mg/ml,0.6 mg/ml,0.7mg/ml, respectively. The concentration of S-GAG in medium conditioned with the monolayer prepared from cumulus cells, thecal cells was 0.14 mg/ml,0.12mg/ml, respectively.7.The concentration of S-GAG (Hep,CS-B,HS,CS-C) was 0.01mg/ml, 0.1mg/ml,1mg/ml,5mg/ml, respectively, which could inhibit cumulus expansion of mouse COCs.8.S-GAG could not inhibit cumulus expansion of goat COCs at any of the concentrations.9.Follicular fluid from 2-4mm follicles could inhibit cumulus expansion of goat COCs.10.Stearic acid(C18:0),oleic acid(C18:1),linoleic acid(C18:2) were the main fatty acid of follicular fluid from 2-4mm and 5-6mm follicles, the concention of linoleic acid (C18:2) was significantly higher in follicular fluid from 2-4mm follicles than from 5-6 mm follicles.In conclusion, follicular fluid from 2-4mm middle follicles contained CEIF activity, which was mainly secrected by thecal cells. S-GAG couldn't inhibit cumulus expansion of goat COCs. S-GAG was not the main CEIF in goat follicles. Linoleic acid may be the major CEIF in goat follicles.