OVARY MORPHOLOGY IN EWES IN DIFFERENT MONTHS OF YEAR

Bìol. Tvarin, 2016, vol. 18, no. 1, pp. 77–86

https://doi.org/10.15407/animbiol18.01.077

OVARY MORPHOLOGY IN EWES IN DIFFERENT MONTHS OF YEAR

I. Lobachova

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The Ivanov’s Institute of Animal Breeding in Steppe Regions «Ascania-Nova»,
1 Chervonoarmiiska str., Ascania-Nova, Chaplynskyi district., Kherson region, 75230, Ukraine

The morphology of ovary of domestic sheep (Ovis aries) of Ascanian Merino breed in different month of year was studied in 2 experiments. In the first (1999–2013) the ovaries in 145 ewes were post-mortally or laparoscopically examined to define the borders of estrous season. Diameter of the greatest follicle, presence of corpus luteum and proliferation in surface layer were estimated. Data were grouped according to calendar month of inspection. In the second experiment the tracing of the change of ovaries morphology in transient from anoestrus to oestrous period was carried. For this purpose 10 ewes of the same flock since July 6^thto revealing of a typical corpus luteum were subjected to weekly laparoscopic examination.

During the period from September to March quantity of animals which had corpus luteum in ovaries varied within 67–100 %. In April the corpus luteum was not observed, in May, July and July it was revealed in 2.6, 11.8 and 11.1 % of animals. Intensification of proliferation in surface layer was noted in April–May, August and October. The noticeable increase of diameter of the greatest follicle occurred in April and September. The seasonal difference is noted between morphology of cells of germinal epithelium — in animals in anestrus the cells were flat, in July they got cubic form, and in August in the majority of animals they became columnar and showed the presence of cilia. During the transition to estrous season the characteristic changes were observed in surface layer. In particular, from the middle of June the ovary surface in majority of animals became dense and whitish and remained such mainly till the end of July–beginning of August. From the middle of July–beginning of August on a surface the small (less 0.5 mm) white specks were appeared. To the middle of August the amount of such formations decreased but among them the part of spots with enlarged (up to 2 mm) diameter increased and the small spots in the form of bagel appeared. Occurrence of specks in the majority of animals preceded intensification of proliferation in ovary surface layer. In the end of August specks disappeared.

By results of experiences it was concluded that anestrous period in Ascanian Merino sheep corresponds to April–July. Also it is assumed that formation and the subsequent transformation of white specks in the end of anestrous period represents one of components of sequence of restoration of cyclicity of sexual activity in sheep and is connected with luteinization of preantral and small antral follicles.

Keywords: SHEEP, SEASONALITY, OVARY, MORPHOLOGY, CORPUS LUTEAL, FOLLICLE

1. Yakovchuk V. S. New technology of intensive fattening of young sheep. Scientific Bulletin “Ascania-Nova”, 2012, no. 5 (1), pp. 213–222. (in Ukrainian)

2. Yakovchuk V. S., Lobachova I. V., Zhulinska O. S., Horlova O. D. Intensification of reproduction is guarantee for effective sheep-breeding management. Animal Industries of Ukraine, 2012, no. 8, pp. 60–63. (in Ukrainian)

3. Kelly R. W., Allison A. J., Shackell G. H. Seasonal variation in oestrous and ovarian activity of five breeds of ewes in Otago. New Zealand J. Exp. Agriculture, 1976, vol. 4, no. 2, pp. 209–214.

4. Christenson R. K. Estrous activity in different breeds and breed crosses of sheep. Theriogenology, 1983, vol. 20, no. 6, pp. 707–713. https://doi.org/10.1016/0093-691X(83)90191-7

5. Jeffcoate I. A., Rawlings N. C., Howell W. E. Duration of the breeding season and response to reproductive manipulation in five breeds of sheep under northern prairie conditions. Theriogenology, 1984, vol. 22, no. 3, pp. 279–290. https://doi.org/10.1016/0093-691X(84)90485-0

6. Jordan K. M. Characterization of seasonal reproduction in Virginia Tech Selection Line, St. Croix, and Suffolk ewes. Katherine Mead Jordan. Thesis Ph.D. in Animal and Poultry Sciences, 2008, Virginia Polytechnic Institute and State University, Virginia.

7. Stekleniov Ye. P. Some aspects of morphology of reproduction of Ascanian Merino sheep. Dr. Ph. biol. sci. autoref. diss. Kyiv, 1960, 16 pp. (in Russian)

8. Davydenko V. M., Shynkarenko I. S., Moldovan T. F., Biletskyi T. M. Effectiveness of heat stimulation in Ascanian Merino sheep in summer period. Sheep-Breeding, 1978, no. 17, pp. 111–116. (in Ukrainian)

9. Bartlewski P. M. Ovarian follicular dynamics during anoestrus in ewes. Thesis M. Sc., 1997, University of Saskatchewan.

10. Bartlewski P. M., Beard A. P., Cook S. J., Rawlings N. C. Ovarian follicular dynamics during anoestrus in ewes. J. Reprod.Fertil., 1998, vol. 1, no. 13, pp. 275–285. https://doi.org/10.1530/jrf.0.1130275

11. Bartlewski P. M., Beard A. P., Rawlings N. C. Ovarian function in ewes at the onset of the breeding season. Anim. Reprod. Sci., 1999, vol. 57, pp. 67–88. https://doi.org/10.1016/S0378-4320(99)00060-3

12. Bartlewski P. M., Vanderpol J., Beard A. P., Cook S. J., Rawlings N. C. Ovarian antral follicular dynarnics and their associations with peripheral concentrations of gonadotropins and ovarian steroids in anoestrous Finnish Landrace ewes. Anim. Reprod. Sci., 2000, vol. 58, pp. 273–291. https://doi.org/10.1016/S0378-4320(99)00092-5

13. Lakin G. F. Biomertrics: a manual for biol. special. of high school. 4^th Ed., Moscow, High School, 1990, 353 pp.

14. Saddick S. Y. Effect of the reproductive cycle on morphology and activity of the ovarian surface epithelium in mammals. Salina Yahya Saddick, Thesis Ph.D., 2010, The University of Edinburgh.

15. Lassoued N., Rekik M., Khenissi S., Merai A. Seasonality of oestrus, ovulation and ovulation rate of Sicilo-Sarde sheep. J. Anim. Physiology Anim. Nutrition, 2014, vol. 98(4), pp. 686–692. https://doi.org/10.1111/jpn.12123

16. Rawlings N. C., Jeffcoate I. A., Rieger D. L. The influence of estradiol-17β and progesterone on peripheral serum concentrations of luteinizing hormone and follicle stimulating hormone in the ovariectomized ewe. Theriogenology, 1984, vol. 22, pp. 473–488. https://doi.org/10.1016/0093-691X(84)90047-5

17. Wheaton J. E., Marchek J. M., Hamra H. A., Al-Raheem S. N. Plasma gonadotropin and progesterone concentrations during the estrous cycle of Finn, Suffolk and Targhee ewes. Theriogenology, 1988, vol. 30, pp. 99–108. https://doi.org/10.1016/0093-691X(88)90267-1

18. Atkinson S., Adams N. R., Martin G. B. Role of progesterone in ovarian follicular growth and development in the sheep. Proc. Aust. Soc. Anim. Prod., 1998, vol. 22, pp. 233–236.

19. Hunter M. G., Southee J. A., McLeod B. J., Haresign W. Progesterone pretreatment has a direct effect on GnRH-induced preovulatory follicles to determine their ability to develop into normal corpora lutea in anoestrous ewes. J. Reprod. Fertil., 1986, vol. 76 (1), pp. 349–363. https://doi.org/10.1530/jrf.0.0760349

20. Skinner D. S., Caraty A., Allingham R. Unmasking the progesterone receptor in the preoptic area and hypothalamus of the ewe: no colocalization with gonadotropin-releasing neurons. Endocrinology, 2001, vol. 142, pp. 573–579. https://doi.org/10.1210/endo.142.2.7956

21. Nilsen J., Brinton R. D. Impact of progestins on estrogen-induced neuroprotection: synergy by progesterone and 19-norprogesterone and antagonism by medroxyprogesterone acetate. Endocrinology, 2002, vol. 143, pp. 205–212. https://doi.org/10.1210/endo.143.1.8582

22. Webster J. C., Pedersen N. R., Edwards D. P., Bach C. A., Miller W. L. The 5’-flanking region of the ovine follicle-stimulating hormone-b gene contains six progesterone response elements: Three proximal elements are sufficient to increase transcription in the presence of progesterone. Endocrinology, 1995, vol. 136, no. 3, pp. 1049–1058. https://doi.org/10.1210/endo.136.3.7867558

23. Oldham C. M., Knight T. W., Lindsay D. R. An explanation for the reduced fertility in Merino ewes at the first oestrus of the breeding season. Proceedings of the Australian Society of Animal Production, 1976, vol. 11, pp. 129–132.

24. Knights M., Hoehn M. T., Lewis P. E., Inskeep E. K. Effectiveness of intravaginal progesterone inserts and FSH for inducing synchronized estrus and increasing lambing rate in anestrous ewes. J. Anim. Sci., 2001, vol. 79, pp. 1120–1131. https://doi.org/10.2527/2001.7951120x

25. Bramley T. A., Stirling D., Menzies G. S., Baird D. T. Reduced LH sensitivity in vivo and in vitro of corpora lutea induced during anoestrus by GnRH, and during the late breeding season, in Scottish Blackface ewes. J. Endocrinol., 2004, vol. 183, pp. 517–526. https://doi.org/10.1677/joe.1.05918

26. Adib A., Freret S., Touze J. L., Lomet D., Lardic L., Chesneau D., Estienne A., Papillier P., Monniaux D., Pellicer-Rubio M. T. Progesterone improves the maturation of male-induced preovulatory follicles in anoestrous ewes. Reproduction, 2014, vol. 148, pp. 403–416. https://doi.org/10.1530/REP-14-0263

27. Legan S. J., Karsch F. J. Photoperiodic control of seasonal breeding in ewes: Modulation of the negative feedback action of estradiol. Biol. Reprod., 1990, vol. 23, pp. 1061–1068. https://doi.org/10.1095/biolreprod23.5.1061

28. Karsch F. J., Bittman E. L., Foster D. L., Goodman R. L., Legan S. J., Robinson J. E. Neuroendocrine basis of seasonal reproduction. Recent Prog. Horm. Res., 1984, vol. 40, pp. 185–232. https://doi.org/10.1016/B978-0-12-571140-1.50010-4

29. Ran Di, Jianning He, Shuhui Song, Dongmei Tian, Qiuyue Liu, Xiaojun Liang, Qing Ma, Min Sun, Jiandong Wang, Wenming Zhao, Guiling Cao, Jinxin Wang, Zhimin Yang, Ying Ge, Mingxing Chu. Characterization and comparative profiling of ovarian microRNAs during ovine anestrus and the breeding season. BMC Genomics, 2014, no. 15, pp. 899–914. https://doi.org/10.1186/1471-2164-15-899

30. Karsch F. J., Robinson J. E., Woodfill C. J., Brown M.B. Circannual cycles of luteinizing hormone and prolactin secretion in ewes during prolonged exposure to a fixed photoperiod: evidence for an endogenous reproductive rhythm. Biol. Reprod., 1989, vol. 41, pp. 1034–1046. https://doi.org/10.1095/biolreprod41.6.1034

31. Vidal A., Médigue C., Malpaux B., Clément F. Endogenous circannual rhythm in luteinizing hormone secretion: insight from signal analysis coupled with mathematical modelling. Phil. Trans. R. Soc. A, 2009, vol. 367, pp. 4759–4777. https://doi.org/10.1098/rsta.2009.0136

32. Caraty A., Franceschini I., Hoffman G. E. Kisspeptin and the preovulatory gonadotrophin-releasing hormone/luteinising hormone surge in the ewe: basic aspects and potential applications in the control of ovulation. J. Neuroendocrinol., 2010, vol. 22 (7), pp. 710–715.

33. Smith J. T., Clay C. M., Caraty A., Clarke I. J. KiSS-1 messenger ribonucleic acid expression in the hypothalamus of the ewe is regulated by sex steroids and season. Endocrinology, 2007, vol. 148, pp. 1150–1157. https://doi.org/10.1210/en.2006-1435

34. L’Anson H., Legan S. J. Changes in LH pulse frequency and serum progesterone concentrations during the transition to breeding season in ewes. J. Repr. Fertil., 1988, vol. 82, pp. 341–351. https://doi.org/10.1530/jrf.0.0820341

35. Yuthasastrakosol P., Palmer W. M., Howland B. E. Luteinizing hormone, oestrogen and progesterone levels in peripheral serum of anoestrous and cyclic ewes as determined by radioimmunoassay. J. Reprod. Fert., 1975, vol. 43, pp. 57–65. https://doi.org/10.1530/jrf.0.0430057

36. Sharma R. K., Batra S. Changes in the steroidogenic cells of the ovaries in small ruminants. Indian J. Anim. Sci., 2008, vol. 78, pp. 584–596.

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