We examined the hormonal and morphologic changes associated with ovarian cyst formation in high-yielding dairy cows. Follicle fluid was aspirated from 90 cysts and 15 preovulatory and 18 subordinate follicles and used for hormonal determination. Pieces of cystic wall were subjected to morphologic and immunohistochemical evaluation. Cysts were characterized by low concentrations of insulin, insulin-like growth factor-I (IGF-I), and glucose and high activity of IGF binding proteins (IGFBPs). Insulin and IGF-I levels were (mean ± SEM) 205 ± 22 pg/mL and 146 ± 42 ng/mL in preovulatory follicles and 3 ± 1 pg/mL and 61 ± 6 ng/mL in cysts, respectively (P < 0.001). Insulin-like growth factor-binding proteins activity was about 10 times higher in cysts than in preovulatory follicles. Cysts were classified into three types according to their estradiol-to-progesterone (E/P) ratio. Type 1 cysts (n = 23) exhibited the highest E/P ratio (10.8 ± 2.3), partial loss of granulosa cells, and severe morphologic changes in the theca interna. Expression of P450 side-chain cleavage and P450 17α-hydroxylase was noted in theca cells and expression of inhibin-α in granulosa cells. Type 2 cysts (n = 35) had a low E/P ratio (0.07 ± 0.02), and patches of luteal-like tissue in the cystic wall. Type 3 cysts (n = 32) had an E/P ratio of 0.91 ± 0.17, and no recognizable granulosa or theca cells. In summary, intrafollicular steroid levels as expressed by E/P ratio, together with IGF-I and insulin levels and morphologic changes in the follicular wall, may serve as accurate cyst-classification parameters. Because IGF-I and/or insulin play an essential role in the final stage of follicle development, it can be speculated that abnormal levels of these metabolic hormones might lead to follicle dysfunction, resulting in follicular regression or cyst formation.
|Original language||American English|
|Number of pages||9|
|State||Published - 15 Sep 2009|
Bibliographical noteFunding Information:
We thank Dr. Parlow of NIDDK for hIGF-I antiserum and hIGF-I, Ido Dafny for excellent technical assistance, and Shamay Yacoby for supervision and care of the animals. This study was supported by the Israeli Cattle Board Committee. This work represents contribution number 519/08, 2008 series from the Agricultural Research Organization, the Volcani Center, Bet Dagan, Israel.
- Follicular fluid