الفهرس 
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Abstract
The present study is an endeavor to investigate the correlation between some different plant oils and reproductive activities in mature female rats. Moreover, the recovery and maturation rates of rat oocytes before and after administration of these oils were obtained as a clue to find out which of oil treatments could be considered as an optimizer to attain successful in vivo and vitro embryo production in rat and otheranimals.
To implement these targets, sixty mature clinically healthy, cycling female Albino rats (150 – 180 g BWT) were used. Rats were left for 2 weeks for acclimatization. Throughout the experimental period, rats were kept under constant environmental and hygienic conditions and offered balanced diet and water ad libitum. Also, to determine the regularity index of the estrous cycle animals were daily examined, in the morning ( 10.00-11.00 am ), through application of vaginal smears and those showing 2 successive regular cycles were included in the current study.
Rats were divided into 5 comparable groups (12 rats/each); control group (I) (received standard ration), group II (received extra virgin olive oil), group III (received sunflower oil), group IV (received soybean oil) and group V (received mixture of sunflower and soybean oil).After 6 weeks of feeding oils addited ration, blood samples were collected individually from all rats throughout the different stages of estrous cycle, At least, five successive estrous cycles from each rat were included.
Oils are chemically analyzed before theiraddition to the diet. Each type of oil was mixed thoroughly at a rate of 10 % of the ration. To minimize oxidation, all diets were prepared once weekly and stored at 4ºC.
Blood sample was collected from the orbital venous plexus of the rat to obtain sera that separated and kept at - 20˚C till hormonal assay (E2 and P4).
Only the females that were not in estrus were scarified after the last blood sample collection, ovaries were harvested; 20 ovaries were used for in vitro maturation and the remaining were preserved separately in 10 % formalin solution for histopathological examination. The obtained data were displayed as mean ± standard error (SE) and subjected to statistical analysis.
The results of chemical analysis revealed that all experimented oils fulfilled the standard health requirements to be added to feed. Moreover, none of the applied oils led to alteration in cellular characteristics of the expected phases of the estrous cycle as compared with those of the controlgroup.
Regarding the gonadal steroids, results of the present study clarified that, throughout the experimental period, in control as well as oil administered females, the highest E2 levels were recorded at proestrous and estrous phases (Table, 2) while, for the highest levels for P4were recorded at postovulatory stages (metestrus and diestrus) of the estrous cycle (Table, 3). It was also noted that the hormonal pattern didn’t differ significantly among different treatments within the same stage of the cycle, except for the group received oil mixture where E2levels decreased significantly (P 0.05) during metestruswhile, P4 decreased significantly (P 0.05) during diestrus phases, respectively.
Concerning IVM, in the treated groups, the highest oocyte recovery rate (RR)(5.43±0.23%,4.41±0.13%)andmaturationrate(MR)(79.17±2.03%,73.43 ± 1.97%) were attained after application of EVOO followed by sunflower oil, respectively. While the lowest values were calculated with the soybean oiland oil mixture (3.83 ± 0.13 %, 2.50 ± 0.16 %) and(68.18± 2.29 %, 62.50 ±2.23%), respectively. It was also noted that there were no significant difference in RR and MR between control and sunflower oil treated groups(Table, 4).
Upon the ovaries, microscopical findings of the ovarian sections of the control as well as EVOO and sunflower oil treated groups disclosed normal ovarian structure with different stages of mature Graafian follicles and multilayered follicular epithelium and corpus luteum. On the contrary, administration of soybean oil alone resulted in severe congestion of the ovarian blood vessels in the medulla with different stages of mature Graafian follicles and corpus luteum) and when mixed with sunflower oil led to severe congestion of ovarian blood vessels with few number of mature Graafian follicles and many corpora lutea.
Conclusion
1- from the present study it could be concluded that none of the administered oils ( EVOO, sunflower and soybean ), within recommended doses, have side effects on the ovarian structure and gonadal hormones level except in oil mixture, so they can be applied to animal feed without the appearance of health hazards upon the safety of the ovaries.
2- In control and treated femalesE2 level increase during proestrus and estrus ( preovulatory and ovulatory stages ) reflects the state that E2 surges are important for ovarian follicles to grow fast . On the other side, P4 exhibited the highest values at metestrus and diestrus( postovulatory stages ) while the lowest ones were recorded at proestrous and estrous phases.
3- The constituents of the applied plant oils (particularly the beneficial fatty acids and antioxidants) have health benefits that can maintain the integrity of both ovarian structure and steroid hormone content within the normal levels.
4- Regarding IVM, from the present study it can be concluded that the protocol used in cattle for oocyte retrieval and IVM can be applied also in female rats. Moreover, the experimented oils maintained the recovery rate within the normal values without being changed except upon using soybean oil and oil mixture. The current study also clarifies that application of either EVOO or sunflower oil favors the media, in female, to enhance oocyte maturation due to the presence of beneficial components of these oils.
Thus, the current study may add a new concept, of interest, to the beneficial health effect of extra virgin olive oil and sunflower oil with special reference to extra virgin olive oil in respect to ovarian integrity.