Relationship among ovarian follicular status,developmental competence of oocytes,and anti‐Müllerian hormone levels: A comparative study in Japanese wild boar crossbred gilts and Large White gilts

The aim of this study was to investigate the ovarian follicular development, developmental competence of oocytes, and plasma anti‐Müllerian hormone (AMH) levels of Japanese wild boar crossbred (wild hybrid) gilts, whose litter size is inferior to that of European breeds. Ovary and plasma samples were collected from two different breeds of gilts (wild hybrid and Large White breeds). The ovaries from the wild hybrid gilts had a lower average numbers of secondary follicles and vesicular follicles in ovarian cross‐sections and of good quality oocytes collected from ovarian follicles as compared with those from Large White gilts (p < 0.05). The development rate to the blastocyst stage of good quality oocytes after in vitro maturation, fertilization and culture was also lower (p < 0.05) in wild hybrid gilts than in Large White gilts. Plasma AMH levels with >0.16 ng/ml were detected in 8.3% of the examined wild hybrid gilts and 33% of the Large White gilts. These results indicate that the low reproductive performance of wild hybrid breed may result in part from low numbers of vesicular follicles and good quality oocytes, and low developmental competence of oocytes. Moreover, plasma AMH levels may support low number of vesicular follicles in ovaries of wild hybrid gilts.     

Effect of season and breed group on the follicular population and cyclicity of heifers under tropical conditions

The aim was to determine the effect of season and breed group on follicular population, and presence and size of CL of heifers under tropical conditions. The seasons were hot-dry (March–June), hot-humid (July–October), and fresh-humid (November–February). Thirty Zebu (Brahman) and 38 F1 (Simmental?×?Brahman) heifers were used. Five evaluations were made in each season, at intervals of 7 days, to assess ovarian activity by ultrasound. Follicles were classified as small (≤4 mm), middle (4.1–8 mm), and large (≥8.1 mm) sizes, and also the size of CL, when present, was measured. Data were analyzed using analysis of variance and logistic regression procedures. Mean number of small follicles was 11.6?±?2.3 with no effect of season, breed group, or their interaction (P?>?0.05). Mean number of middle follicles was influenced by season and breed group; the highest average was found in the fresh-humid season (4.0?±?0.2) and in F1 heifers (3.6?±?0.2; P?<?0.05). The highest mean number of large follicles was in the hot-humid season (1.4?±?0.1; P?<?0.05). The highest maximum follicle diameter (MFD) mean was registered in the hot-humid season (1.3 mm; P?<?0.05) and the lowest proportion of heifers with CL occurred in fresh-humid season (33.3%; P?<?0.05). No effect of season, breed group, and interaction on the maximum diameter of the CL was found. In conclusion, season was a very important source of variation. Heifers in the hot-humid season had the largest follicles and MFD, and better cyclicity.

     

Effect of Follicle Size on In Vitro Maturation of Pre‐Pubertal Porcine Cumulus Oocyte Complexes

Very small follicles (<3.0 mm diameter) are over‐represented on the surface of ovaries of non‐cycling pigs, and the oocytes collected from these follicles generally have reduced developmental competence in vitro. This study examined the effect of follicle size on the nuclear maturation (n = 608), the potential of parthenogenetic activation (n = 243) and the cyclic AMP (cAMP) content of pre‐pubertal porcine oocytes (n = 480). In addition, the influence of follicle size on steroid hormone synthesis was analysed. Cumulus oocyte complexes (COCs) flushed from small (2.5–4.0 mm) or large (4.5–6.0 mm) ovarian follicles were cultured for 0, 28 and 46 h. After 46 h of IVM, a greater proportion of oocytes from 4.5‐ to 6.0‐mm follicles reach metaphase II (MII) compared with those from follicles with 2.5–4.0 mm of diameter (96.1 vs 77.0%, respectively; p < 0.001). Parthenogenetic activation of oocytes from large follicles produced higher developmental rates than oocytes from large follicles (p < 0.05). At 28 h, the IVM medium with oocytes from large follicles contained significantly more 17ß‐oestradiol (E₂) than the medium with oocytes from small follicles (5.55 vs 3.45 ng/ml, respectively; p < 0.05) and at 46 h, the medium with oocytes from small follicles contained significantly more progesterone (P₄) than the medium with oocytes from large follicles (276.7 vs 108.2 ng/ml, respectively, p < 0.05). Porcine oocytes from large follicles have higher nuclear and cytoplasmic maturation capacities, but the differences did not appear to be cAMP‐mediated. Our findings also suggest that COCs from small follicles undergo more intensive luteinization than COCs from large follicles. The results show that oocytes from follicles with a diameter greater than 4.0 mm are more suitable for in vitro studies.     

Effects of the Reproductive Status on Morphological Oocyte Quality and Developmental Competence of Oocytes after In Vitro Fertilization and Somatic Cell Nuclear Transfer in Cat

This study was conducted to examine the effects of the reproductive cycle of donor cat on the quality of oocytes at recovery and developmental competence of oocytes after in vitro fertilization (IVF) and somatic cell nuclear transfer (NT). Based on the presence or absence of follicles and corpora lutea, the ovarian pairs collected were classified into inactive, follicular or luteal stages. After collection of oocytes, the oocytes were classified into four grades according to the morphological condition of oocyte cytoplasm and cumulus cells. A total of 16 558 oocytes were obtained from 198 ovarian pairs. The total mean numbers of oocytes and the mean numbers of oocytes with high quality (grade I) were significantly higher in ovarian pairs at the inactive stage (111.1 and 19.0 oocytes, respectively) than in ovarian pairs at the follicular stage (67.1 and 11.4 oocytes, respectively). A significant difference in the proportions of oocytes with grade I out of the total examined oocytes was observed between the follicular and luteal stages of ovaries (14.9% vs 20.2%, p < 0.05). The proportions of IVF embryos cleaved and developed to blastocysts significantly decreased with decreased quality of oocytes at recovery, irrespective of the reproductive status of ovaries. Moreover, there were no significant differences in the proportions of cleavage and development to the blastocyst stage of IVF and NT embryos among three oestrous stages of ovaries. These results indicate that the reproductive cycle stage of donor cat ovaries has no apparent effects on the in vitro development of oocytes after IVF and NT, but the quality of oocytes at recovery influences the development of IVF embryos.     

Evaluation of Follicular Development and Oocyte Quality in Pre‐pubertal Cats

Our study was conducted to assess the follicular development and availability of sound ovarian oocytes for in vitro production (IVP) of embryos in pre‐pubertal cats. The relationship between body and ovarian weight was examined in 93 cats. The results revealed that ovarian weight rapidly increased until 100 days of estimated age. By histological evaluation of ovaries obtained from 11 pre‐pubertal cats with estimated age of <20, 20–40 and 100–120 days, it was clarified that the increase in ovarian weight during kitten growth accompanied the increase in the number and size of antral follicles. The follicular diameter and percentage of normal oocytes in secondary/antral follicles also increased as estimated age (body weight) increased. The oocytes obtained from pre‐pubertal cats with 100–120 days of estimated age were used for IVP of embryos. The results showed that the success rates of in vitro maturation, in vitro fertilization and development to blastocysts after in vitro culture in pre‐pubertal cats were lower than in sexually mature cats. However, the percentage of blastocysts based on the cleaved embryos and cell number of blastocysts in pre‐pubertal cats were comparable to those in mature cats. In conclusion, these results suggest that the ovaries of pre‐pubertal cats with ≥100 days of age contain oocytes with in vitro developmental competence to blastocysts.     

Production of Ban miniature pig embryos by in vitro fertilization: A comparative study with Landrace

Ban is an endangered miniature pig breed in Vietnam. This study aimed to set up an in vitro embryo production (IVP) system for this breed. Ban's epididymal sperm concentration (1240 ± 35 × 10⁶/mL) was lower (P < 0.01) compared with Landrace (4160 ± 42 × 10⁶/mL). However, sperm characteristics before and after freezing in Ban and Landrace were similar. The numbers of follicles with diameter larger than 2 mm per ovary in Ban females treated with equine chorionic gonadotropin and human chorionic gonadotropin (27.1 ± 1.3) were higher (P < 0.05) than those in Landrace (12.9 ± 2.0) and in non‐hormone stimulated Ban (no > 2 mm follicles). After in vitro maturation, the percentages of oocytes with expanded cumulus cells and the first polar body (matured oocytes) were not different among Ban, hormone‐stimulated Ban and Landrace. The percentages of two‐cell embryos and morulae derived from oocytes collected from three sources did not differ. However, the rate of blastocysts derived from oocytes in non‐stimulated Ban (4.0 ± 3.8%) was lower (P < 0.05) than that in Landrace (15.3 ± 1.8%). In conclusion, an effective IVP system for good quality embryos in Ban, that is essential for genetic conservation of this breed, was established.     

Presence of Leptin and Its Receptor in the Hypothalamus,Uterus and Ovaries of Swine Females Culled with Distinct Ovarian Statuses and Parities

Leptin acts on energy metabolism, affecting reproductive functions through activation of its receptors in the brain and in reproductive organs. This study compared the presence of leptin and its receptor (ObR‐b) in hypothalamus neurons, endometrial glands and oocytes of culled swine females across ovarian statuses and parities. Immunohistochemistry was done in samples of uterus, ovaries and hypothalamus from 28 culled females, using polyclonal antibodies antileptin and ObR‐b. Immunolabelling was compared for sows categorized by parity at culling (0, 1, 2–4 and <4) and ovarian status (luteal and follicular phases of the oestrous cycle and with cysts). Immunolabelling for leptin and ObR‐b in neurons and oocytes was weaker in females with cysts (p < 0.05) than in those at the follicular phase. In endometrial glands, leptin immunolabelling was less intense in females with cysts (p < 0.05), but immunolabelling for ObR‐b was similar across ovarian statuses (p > 0.05). In sows culled with 2–4 parities, leptin immunolabelling in neurons and endometrial glands was more intense than in nulliparous females (p < 0.05). In comparison with sows culled at greater parities, ObR‐b immunolabelling for nulliparous females was less intense in endometrial glands and in oocytes (p < 0.05), but more intense in neurons (p < 0.05). Thus, in swine, the presence of leptin and ObR‐b varies across parities and is more intense in the uterus, ovaries and hypothalamus of females that were cycling before culling than in those having cystic ovaries.     

Cystic Degeneration in Porcine Ovaries - First Communication: Morphology of Cystic Ovaries, Interpretation of the Results

Contents: The morphological appearance of ovarian structures in 79 sows with ovarian cysts was examined. Sixty sows had been culled due to sterility; 19 sows had been repeatedly investigated clinically before slaughter. It was found that cystic ovaries without corpora lutea (CL) had the largest diameter and volume (151.3 cm³), in comparison to both cystic ovaries with CL (85.7 cm³) and normalovaries (16.9 cm³). The number of cysts on ovaries without corpora lutea was approximately twice as high as on the ovaries with CL (23.3 vs 12.1 cystslsow; p < 0.001). A combined form of degeneration consisting of large (> 1.5 cm in diameter) and small (1.5 em in diameter) cysts was found in 63% of the animals, whereas degeneration with only small cysts occured in 8% of the cases. Dark CL, interpreted as being functional, were mainly present in animals with up to 10 cysts per sow (24 out of 27 sows, p < 0.001); pale CL, interpreted as being weakly functional, were mainly found on ovaries with more than 10 cysts (19 out of 23 sows; p < 0.001). Based on macroscopical differentiation cyclic activity was found to be dependent to the number of cysts. Regular or irregular estrous cycles were observed in oligocystic animals (10 cysts/animal) with functional CL (58%). Up to 75% of the animals with pale or absent CL showed no estrous activity.     

Ovarian activity,transuterine embryo migration and prenatal losses in Ethiopian highland ewes

A study was conducted on 1442 Ethiopian highland ewes to determine the seasonality of ovarian activity, intrauterine embryo migration and prenatal reproductive wastage. Assessment of ovarian follicular activity revealed that a higher (p < 0.01) proportion of ewes ovulated in the dry season than in the heavy and light rainy seasons. However, there was a tendency (p = 0.057) of decline in the mean number of ovulations per ewes during the light rains. The mean diameter of the largest follicle on the ipsilateral ovary was higher (p < 0.01) in both ewes with single and those with twin corpora lutea (CL) than on the contralateral ovary; and, compared to ewes with single CL, it was higher (p < 0.05) in those with twin CL. The right ovary was more active (p < 0.001) only in single-ovulating ewes. Similarly, a higher (p < 0.001) proportion of ewes were pregnant in the right horn. Embryos migrated to the opposite horn in single-, twin- and triple-ovulating ewes. There was a higher (p < 0.001) tendency for the left-to-right migration than the opposite. There was significant (p < 0.01) association between embryo loss and site and number of ovulations. Embryo loss was higher (p < 0.01) in ewes with twin ovulations on the right ovary. It is very likely that these results indicate a better chance of embryo survival in the right uterine horn.     

Survival of embryos and calves derived from somatic cell nuclear transfer in cattle: a nationwide survey in Japan

To obtain data concerning the survival of embryos and calves derived from somatic cell nuclear transfer (SCNT) in Japan, a nationwide survey was carried out in April, 2009. As a result, data concerning 3264 embryo transfers (ETs) with SCNT embryos which produced 301 calves were accumulated and their survival was analyzed. The present survey revealed that survival rates of transferred bovine embryos and produced calves derived from SCNT had not improved over a decade (1998–2007). A remarkable feature of the pregnancies with SCNT embryos was a high incidence of spontaneous abortions. When the decade was divided by the occurrence of bovine spongiform encephalopathy (BSE) in 2001, significant decreases in the ‘after BSE’ period (2002–2007) were observed in the percentages of calves born (P < 0.01), calves living at birth (P < 0.05), calves living for 24 h (P < 0.05) and 6 months (P < 0.01). Abortions that occurred during 61–99 days after ETs were significantly increased (P < 0.01) in the ‘after BSE’ period. Certain kinds of regeneration that occurred in oocytes during the 15–20 h of storage of bovine ovaries at 10–15°C as a part of BSE inspection might have had some negative effects on SCNT embryos when these oocytes were used as recipients of SCNT.     

Oocyte quality and viability in Nguni and Hereford cows exposed to different levels of dietary protein

High blood urea nitrogen (BUN) concentration decreases fertility in ruminants. Nguni cattle are reported to maintain BUN concentration more efficiently than other beef breeds. Our objectives were to determine if BUN concentration differed between Nguni and Hereford cows exposed to a high protein ration, and if breed or BUN and serum protein concentrations at the time of oocyte pick-up affected oocyte quantity, quality, and viability. Twelve Nguni and 10 Hereford cows were randomized into high or normal BUN-inducing diets in a crossover design. Ultrasound-guided oocyte pick-up was performed twice weekly; oocytes were counted, visually graded and the viable oocytes were pooled by treatment and breed for in vitro maturation, fertilization, and culture. Nguni cows on the highest protein ration achieved lower mean BUN concentration than Herefords (P < 0.05), and Nguni cows reached BUN concentrations above 20 mg/dL less frequently than Herefords (P = 0.03). Donor BUN concentration above 20 mg/dL at the time of oocyte pick-up, but not breed, independently decreased the number of good quality oocytes harvested. Increasing weighted mean serum albumin of donor cows was independently associated with the number of oocytes that cleaved by day 2 and that reached morula stage by day 7 (P = 0.01). In conclusion, Nguni cows reached the critical threshold of 20 mg/dL BUN less frequently than Herefords; BUN of donor cows above 20 mg/dL negatively affected visual oocyte quality independent of breed, and increasing serum albumin of donor cows improved viability of bovine oocytes.

     

6月龄和成年牦牛卵巢及卵泡发育状况研究

为了研究6月龄牦牛和成年牦牛卵巢及表面卵泡发育状况,试验比较了6月龄和成年牦牛卵巢长度、宽度、厚度、重量、卵泡数量以及卵母细胞体外成熟培养效果。结果表明:成年牦牛卵巢长度(2.29±0.43)cm、宽度(1.91±1.31)cm和厚度(1.60±1.90)cm均显著大于6月龄牦牛[(1.65±0.30)cm、(1.14±0.25)cm、(0.79±0.26)cm](P<0.05),成年牦牛卵巢体积(6.92±7.00)cm3和重量(3.19±1.58)g极显著大于6月龄牦牛体积(1.63±0.93)cm3和重量(0.87±0.44)g(P<0.01)。6月龄牦牛Ⅰ级卵泡数(14.47±8.74)枚和平均总卵泡数(15.17±8.87)枚极显著高于成年牦牛Ⅰ级卵泡数(7.97±3.72)枚和平均总卵泡数(8.98±3.87)枚(P<0.01),Ⅱ级卵泡数差异不显著(P>0.05),成年牦牛平均每头含(0.02±0.15)枚Ⅲ级卵泡,而6月龄牦牛无Ⅲ级卵泡。成年牦牛有黄体卵巢重量显著大于无黄体卵巢重量(P<0.05),有黄体卵巢含(0.06±0.24)枚Ⅲ级卵泡,而无黄体卵巢不含Ⅲ级卵泡。6月龄和成年牦牛A、B级卵母细胞体外培养成熟率分别为(81.39±3.53)%、(80.44±4.50)%,差异不显著(P>0.05),而6月龄牦牛卵巢的平均卵母细胞数和平均A、B级卵母细胞数均显著高于成年牦牛(P<0.05)。     

Immunohistochemical Localization of Fibroblast Growth Factor‐2 in the Sheep Ovary and its Effects on Pre‐antral Follicle Apoptosis and Development In Vitro

Studies with sheep are important to improve our knowledge about the factors that control folliculogenesis in mammals and to explore possible physiological differences among species. The aims of this study were to characterize FGF‐2 protein expression in ovine ovaries and to verify the effect of FGF‐2 on the morphology, apoptosis and growth of ovine pre‐antral follicles cultured in vitro. After collection, one fragment of ovarian tissue was fixed for histological analysis and TUNEL analysis (fresh control). The remaining fragments were cultured for 7 days in control medium (α‐MEM⁺) alone or supplemented with FGF‐2 at different concentrations (1, 10, 50, 100 or 200 ng/ml). After culturing, ovarian tissue was destined to histology and TUNEL analysis, and oocyte and follicle diameters were measured. The immunostaining for FGF‐2 was observed in oocytes from primordial, primary and secondary follicles, as well as in granulosa cells of secondary and antral follicles. The percentage of normal follicles was similar among control medium, 1 and 10 ng/ml FGF‐2, and significantly higher than those observed in 50, 100 or 200 ng/ml FGF‐2. A significant increase in follicle diameter was observed when tissues were cultured in 10, 50, 100 or 200 ng/ml FGF‐2 compared with the fresh control and the other treatments. Similar results were observed for oocyte diameter in tissues cultured with 50, 100 or 200 ng/ml FGF‐2 (p < 0.05). However, the percentage of apoptotic cells only decreased (p < 0.05) in ovarian tissues cultured in 1 or 10 ng/ml FGF‐2 compared with the control medium and other FGF‐2 treatments. In conclusion, this study demonstrated the presence of FGF‐2 in ovine ovaries. Furthermore, 10 ng/ml FGF‐2 inhibits apoptosis and promotes ovine follicle growth. As the sheep ovary is more similar to that of humans, the culture system demonstrated in this work seems to be an appropriate tool for studies towards human folliculogenesis.     

Melatonin and CIDR improved the follicular and luteal haemodynamics,uterine and ovarian arteries vascular perfusion,ovarian hormones and nitric oxide in cyclic cows

This study hypothesizes that melatonin with exogenous progesterone (CIDR) can improve follicular, luteal, ovarian and uterine haemodynamic of heat-stressed cows. Holstein cows (N = 12) studied for two spontaneous oestrous cycles during winter then divided equally during summer into the CIDR group received CIDR for 7 days and the melatonin group (Mel) received three injections of melatonin (75 mg/head) at the CIDR insertion, removal and ovulation days. Blood samples were collected to assay oestradiol (E2), progesterone (P4) and nitric oxide (NO). On day 0 (Ovulation), Mel had more small follicles (p < .05), higher ipsilateral and contralateral ovarian arteries (Ov.A.) peak systolic velocity (PSV), higher ipsilateral uterine artery (Ut.A.) PSV (p = .031) and blood flow volume (BFV), also Mel elevated contralateral Ut.A. PSV and BFV (p < .0001) but lowered contra Ut.A. pulsatility index (PI, p < .0001), E2 (p < .01) and NO (p < .0001). Mel increased the corpus luteum diameter (CL, p < .001), coloured area (p < .007) and P4 (p < .0001) on day 5 and reduced them (p < .05; p < .01) on Day 14. On day 10, Mel obtained CL diameter (p < .03) and coloured area (p < .002) of spontaneous that was higher than CIDR and decreased P4 (p < .003). Mel increased CL diameter, area and coloured area and decreased them thereafter. Mel increased the ipsilateral ovarian and uterine arteries PSV and BFV before ovulation and until day 8. Mel increased P4 and decreased NO until days 6 and 14. In conclusion, the improvement in follicular, luteal, ovarian and uterine haemodynamic and the decrease of NO production proved our hypothesis Melatonin doses higher than 75 mg/head is recommended to improve the heat-stressed cow's fertility.     

Protein Localization of Epidermal Growth Factor in Sheep Ovaries and Improvement of Follicle Survival and Antrum Formation In Vitro

The aims of this study were to characterize EGF protein expression in ovine ovaries and to verify the effect of EGF on the in vitro development of isolated pre‐antral follicles. After collection, ovarian tissue was fixed for immunohistochemical analysis. Additional pairs of ovaries were collected, and secondary follicles were cultured for 18 days in α‐MEM⁺ (control) alone or supplemented with EGF (1, 10 or 50 ng/ml). The immunostaining for EGF was observed in oocytes from pre‐antral and antral follicles, in granulosa cells of primary and secondary follicles, as well as in cumulus and mural cells of antral follicles. After 18 days, the results showed that treatment with 50 ng/ml EGF significantly increased the percentage of morphologically normal follicles compared with the control group (α‐MEM⁺) and significantly reduced the precocious extrusion of oocytes and increased the percentage of antral follicles compared with the control and 1 ng/ml EGF. All the treatments induced a progressive and significant increase of the follicular diameter throughout the period of culture. However, there were no significant differences in follicular diameter or in the daily growth rate among treatments. In conclusion, this study demonstrated the presence of EGF in ovine ovaries. Moreover, 50 ng/ml EGF increased the percentage of normal follicles and improved antrum formation in isolated ovine follicles after 18 days of in vitro culture.     

Effects of breed and ejaculate volume on sperm morphology and semen parameters of boars

The aim of the study was to determine the relation between the semen quality, frequency of sperm defects, sperm dimensions and shape, and the ejaculate volume of Large White and Landrace boars. A total of 648 ejaculates collected from 31 Large White and 30 Landrace boars were divided into three groups according to the criterion of the ejaculate volume. In this study Landrace boars produced ejaculates with higher volume, sperm concentration, and total numbers of spermatozoa than Large White boars. Landrace boars also showed a lower frequency of sperm with morphological abnormalities (P < 0.05). Landrace boars sperm had larger heads, which were by 0.15 μm longer, and by a larger perimeter and area (P < 0.05). Landrace boar spermatozoa also had a longer flagellum and were generally larger and by 2.07 μm longer than Large White boar sperm (P < 0.05). Significant differences were also found in the shape of sperm of the two breeds (P < 0.05). Landrace boars sperm had more elongated heads, and the ratio of head size to flagellum length was lower than in Large White boars sperm (P < 0.05). Sperm from ejaculates with low volume had a shorter flagellum and a greater head length/flagellum length ratio than sperm from medium- and high-volume ejaculates (P < 0.05).     

Vitrification with DAP 213 and Cryotop of Ex Situ and In Situ Feline Cumulus–Oocyte Complexes

This study was undertaken to compare cryotolerance, in terms of viability and resumption of meiosis after warming and culture (24 and 48 h), of ex situ (isolated) and in situ (enclosed in the ovarian tissue) feline cumulus–oocyte complexes (COCs) vitrified with DAP 213 (2 m DMSO, 1 m acetamide, 3 m propylene glycol) in cryotubes or Cryotop method. Ovaries were harvested from 49 pubertal queens. Of each pair of ovaries, one was dissected to release COCs randomly divided into three groups: fresh COCs (control), ex situ COCs vitrified with DAP 213 and Cryotop. The cortex of the other ovary was sectioned into small fragments (approximately 1.5 mm³) and randomly assigned to be vitrified by DAP 213 or Cryotop. After warming, ex situ and in situ (retrieved form vitrified ovarian tissue) COCs were matured in vitro. Viability of oocytes was highly preserved after warming and culture in all treatments. Proportions of oocytes surrounded by complete layers of viable cumulus cells were remarkably decreased (p < 0.00001) in both vitrification procedures compared to fresh oocytes. Resumption of meiosis occurred in all treatments. After 24 h of culture, results were similar in ex situ and in situ vitrified oocytes regardless of the vitrification protocol used (range 29–40%), albeit lower (p < 0.05) than those of fresh oocytes (65.8%). After 48 h of culture, ex situ oocytes vitrified with Cryotop achieved the rates of meiosis resumption similar to fresh oocytes (53.8% vs 67.5%; p > 0.05) and ex situ and in situ oocytes vitrified with DAP 213 showed similar rates of resumption of meiosis. These findings demonstrated that DAP 213 and Cryotop preserve the viability of ex situ and in situ oocytes, but cumulus cells are highly susceptible to vitrification. However, the capability to resume meiosis evidences that feline immature oocytes vitrified as isolated or enclosed in the ovarian cortex have comparable cryotolerance.     

Ovarian follicular dynamics and hormones throughout the estrous cycle in Thai native (Bos indicus) heifers

Relatively few studies have been reported regarding the reproductive physiology of female Thai native cattle. Therefore, the objective of the present study was to evaluate the follicular dynamics and concentrations of follicle stimulating hormone (FSH), estradiol (E2) and progesterone (P4) during the estrous cycle in Thai native heifers (TNH) and to compare obtained results with those of European and Indian cattle breeds previously reported. For the detection of estrus, ovaries of all 20 heifers were examined twice daily (12 h intervals) by ultrasonography for three consecutive estrous cycles. From data of 60 estrous cycles (n = 60 estrous cycles from 20 heifers), it was found that 14 (70%) and 6 heifers (30%) had two (42 estrous cycles collected from 14 heifers) and three follicular waves (18 estrous cycles collected from 6 heifers), respectively. The days when estrus was detected, interovulatory intervals, life‐spans of corpus lutea (CL), and days for growing and regression of CLs were shorter in the two follicular waves than those in the three follicular waves (P < 0.05). In both two and thre follicular waves, larger maximum diameters and higher growth rates of the dominant follicle (DF) in an ovulatory wave were observed than those of the preceding waves without ovulation (P < 0.05). There was a progressive increase in follicular size and FSH and E2 production during follicular growth in each follicular wave. In addition, the FSH and E2 peak concentrations during the ovulatory wave were higher than those of the anovulation waves (P < 0.05). Moreover, although the ovarian follicular dynamic patterns in Thai native heifers were similar to those previously reported for European and Indian cattle breeds, the diameter of the largest preovulatory follicle (OF), subordinate follicles (SF) and CLs were smaller than those in European and Indian cattle breeds. In conclusion, when compared with European and some breeds of Indian cattle, the length of interovulatory intervals was shorter, and the sizes of dominant SF and CLs were smaller in Thai native heifers.     

Follicular characteristics and intrafollicular concentrations of nitric oxide and ascorbic acid during ovarian acyclicity in water buffalo (Bubalus bubalis)

The objective of this study was to examine the follicular characteristics and intrafollicular concentrations of nitric oxide and ascorbic acid during ovarian acyclicity in buffaloes. Ovaries were collected from 56 acyclic and 95 cyclic buffaloes at slaughter, surface follicle number was counted and follicles were classified into small (5.0–6.9 mm), medium (7.0–9.9 mm), and large (≥10.0 mm) size categories based on their diameter. Follicular fluid was aspirated and assayed for nitric oxide, ascorbic acid, estradiol, and progesterone. Acyclic buffaloes had a higher (P < 0.05) number of medium-sized follicles and a lower (P < 0.001) number of large follicles than the cyclic ones. In acyclic animals, the number of large follicles was lower (P < 0.01) than in medium size category which in turn was lower (P < 0.001) than the number of small follicles. In contrast, the number of medium and large follicles was not different (P > 0.05) in the cyclic control. However, the number of small-sized follicles was higher (P < 0.001) compared to the other two categories. The incidence of large-sized follicles was lower (P < 0.05) in acyclic buffalo population compared to the cyclic control. Evaluation of estrogenic status demonstrated that all the follicles of acyclic buffaloes are estrogen-inactive (E ₂/P ₄ ratio < 1). Small- and medium-sized follicles of acyclic buffaloes had higher concentrations of nitric oxide (P < 0.05 and P < 0.001, respectively) and lower concentrations of ascorbic acid (P < 0.05 and P < 0.01, respectively) than the corresponding size estrogen-active follicles of their cyclic counterparts. In conclusion, this study indicates that follicular development continues during acyclicity in buffaloes. Although follicles in some acyclic buffaloes attain a size corresponding to morphological dominance, they are unable to achieve functional dominance, perhaps due to an altered balance of intrafollicular nitric oxide and ascorbic acid and, as a result, these follicles instead of progressing to ovulation undergo atresia.     

SRT1720 enhances maturity and quality of oocytes in aged mice

This study aims to investigate the morphology and distribution of mitochondria, spindles, and chromosomes in oocytes of aged mice and examine the effects of SRT1720 on oocyte maturation. C57BL/6J mice were divided into young (4–8 weeks) and aged groups (48–52 weeks). In vitro maturation media contained (0.05, 0.1, and 1.0 μM) SRT1720 and 0.1-μM dimethyl sulfoxide (DMSO control). The rate of chromosome misalignment and spindle misorientation in oocytes of aged mice were significantly higher than that of young mice (P < 0.01). Fluorescence intensity of mitochondria from oocytes of aged mice was significantly lower than that of young mice (P < 0.01). SRT1720 at 0.1 μM significantly improved oocyte maturation, fertilization, and blastocyst formation in aged mice compared with young mice (P < 0.01). Additionally, immunofluorescence intensity of mitochondria, normal spindle morphology, and chromosome alignment were notably enhanced with SRT1720 when compared with the DSMO control group for metaphase II (MII)-stage oocytes matured in vitro (P < 0.01); 0.1-μM SRT1720 enhanced the expression level of SRIT1 in oocytes from aged mice. In summary, the aged mice oocytes showed increased nuclear and cytoplasmic defects, whereas SRT1720 enhanced oocyte maturation and quality. We concluded that 0.1-μM SRT1720 was an appropriate concentration for in vitro maturation media.