Markers of ovarian antral follicular development in sheep: comparison of follicles destined to ovulate from the final or penultimate follicular wave of the estrous cycle

• Published in: Reproduction (Cambridge, England) Vol. 140; no. 4; pp. 559 - 568
• Main Authors: Seekallu, Srinivas V, Toosi, Behzad M, Grazul-Bilska, Anna T, Rawlings, Norman C
• Format: Journal Article
• Language: English
• Published: England BioScientifica 01.10.2010; BioScientifica Ltd; Society for Reproduction and Fertility
• Subjects: Animals; Connexin 43 - genetics; Connexin 43 - physiology; Dinoprost - pharmacology; Estradiol - analysis; Estrous Cycle - physiology; Factor VIII - genetics; Factor VIII - physiology; Female; Follicle Stimulating Hormone - physiology; Granulosa Cells - physiology; Immunohistochemistry - veterinary; Medroxyprogesterone Acetate - pharmacology; Ovarian Follicle - physiology; Ovulation - physiology; Progesterone - blood; Proliferating Cell Nuclear Antigen - genetics; Proliferating Cell Nuclear Antigen - physiology; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - chemistry; RNA, Messenger - genetics; Sheep - physiology; Theca Cells - physiology; Vascular Endothelial Growth Factor A - genetics; Vascular Endothelial Growth Factor A - physiology
• ISSN: 1470-1626; 1741-7899
• DOI: 10.1530/REP-10-0064

Treatment of non-prolific western white-faced ewes with prostaglandin F2α (PGF2α) and medroxyprogesterone acetate (MAP) increases the ovulation rate as a result of ovulations from the penultimate wave in addition to the final wave of the cycle. The objective of the current study was to evaluate the expression of markers of vascularization/angiogenesis, a marker of intercellular communication, and cellular proliferation and apoptosis in follicles from the penultimate and final waves. On day 8 of the estrous cycle, 15 ewes were administered a single injection of PGF2α and an intravaginal MAP sponge, which remained in place for 6 days. Two days after sponge removal, ovaries which contained follicles from the penultimate and final waves were collected and processed for immunohistochemistry followed by image analysis, and for quantitative real-time RT-PCR. Expression of factor VIII (marker of vascularization), proliferating cell nuclear antigen, and GJA1 (Cx43; marker of gap junctional communication) was greater (P<0.05) in follicles from the final wave compared with follicles from the penultimate wave. For theca cells, mRNA expression for vascular endothelial growth factor (VEGF) was greater (P<0.05) and tended to be greater (P≤0.1 and ≥0.05) for GJA1 and endothelial nitric oxide synthase in follicles from the final wave compared with follicles from the penultimate wave. For granulosa cells, the mRNA expression for GJA1 was greater (P<0.05) and tended to be greater (P≤0.1 and ≥0.05) for VEGF in follicles from the final wave compared with follicles from the penultimate wave. In conclusion, extension of the lifespan of follicles in the penultimate wave reduces follicular viability in the ewe.