Immunopharmacology and Immunotoxicology, 2009, 1–5, iFirst Address for Correspondence: Prof. Sciorsci Rafaele Luigi, Strada Provinciale per Casamassima Km 3, 70010 Valenzano (Bari) Italy. E-mail: r.sciorsci@ veterinaria.uniba.it (Received 20 March 2009; accepted 30 March 2009) Introduction Cystic Ovarian Follicles (COF) is an important cause of subfertility in dairy cattle, since they prolong the calv- ing interval. (1–3) A cystic follicle has been traditionally defned as an anovulatory follicle persisting for more than 10 days, with a diameter larger than 25 mm, with- out luteal tissue (4,5) However, other authors reported, a diameter lesser than 20 mm (6,7) and more than 17 mm (8,9) and persistence for a minimum of 7 days as diagnostic criteria of COF. Moreover, small cystic follicles with a diameter of 15– 20 mm do not histologically difer from cystic follicles larger than 25 mm. (10) Follicular cysts, which have a wall less thick than 3 mm and are accom- panied by a plasma progesterone (P 4 ) concentration lesser than 1 ng/ml, are diferent from luteal cysts, which have a wall thicker than 3 mm and are accompanied by plasma P 4 concentration superior than 1 ng/ml. (11–13) Te etiopathogenesis of the follicular cysts is multifac- torial and still not well clarifed in all its endocrine, histo- logical, clinical and therapeutic aspects. Many studies have pointed out certain dysfunctions of the hypothalamus- hypophysis-ovary axis as well as alterations of the lutein- izing hormone receptor, follicle stimulating hormone recep- tor and estradiol receptor-b expression, the main factors involved in this pathology. (7,8,13–24) Commonly, the fnal step leading to COF is the failure of the endocrine mecha- nism of ovulation. (25,26) Recently, ovulation has been compared to an acute infammatory process (27–29) during which vasoactive agents, prostanoids and leukotrienes develop, (30–34) An infux of immune cells and an increased concentration of cytokines and proteases occur during the Luteinizing Hormone (LH) peak. (35) Tumor necrosis factor -a (TNF-) is one of the main cytokines involved in this process and has emerged as a putative mediator of ovulation. (35–38) In this process, ovarian surface epithelium cells (OSEs) exert an important role. In fact, during each reproductive cycle, OSEs take part in the cyclical ovulatory rupture and repair. In the preovulatory follicle, in fact, these cells undergo apoptosis at the time of ovulation. (25,39,40) OSEs, in close contact with the apical wall of preovulatory fol- licles, secrete a urokinase type -Plasminogen Activator (u-PA), in response to surge concentrations of LH. u-PA ISSN 0892-3973 print/ISSN 1532-2513 online © 2009 Informa UK Ltd DOI: 10.1080/08923970902932962 Abstract Ovulation is compared to an acute infammatory process during which vasoactive agents, prostanoids, leukotrienes and Reactive Oxygen Species (ROS) develop. The aim of this study was to evaluate the lev- els of ROS in cystic and follicular fuid, in order to establish their involvement in the etiopathogenesis of Cystic Ovarian Follicle (COF) in dairy cows. The study was conducted in 30 healthy cows (group C) and 30 cows afected by COF (group COF). The fuid of follicular cysts and of preovulatory follicles was drawn by means of ultrasound guided aspiration from the cows of both groups. The fuid obtained was analyzed by a photometric analytical system to detect ROS level. ROS concentration was statistically lower in the cystic fuid than in the follicular one (62.4 ± 13.36 U.Carr vs. 84.89 ± 26.99 U.Carr) (p<0.05), thus suggesting that an alteration of the cascade responsible for ROS production may be implicated in the complex etipathogen- esis of COF. Keywords: Reactive Oxygen Species; follicular cysts; bovine; ovulation; apoptosis http://www.informapharmascience.com/ipi RESEARCH ARTICLE Reactive Oxygen Species (ROS): involvement in bovine follicular cysts etiopathogenesis Annalisa Rizzo, Guseppe Minoia, Carmelinda Trisolini, Maddalena Mutinati, Massimo Spedicato, Felicita Jirillo, and Rafaele Luigi Sciorsci Department of Animal Production, University of Bari Bari, Italy .