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Cumulus expansion, chromatin configuration and meiotic competence in horse oocytes: a new hypothesis

, : Cumulus expansion, chromatin configuration and meiotic competence in horse oocytes: a new hypothesis. Equine Veterinary Journal. Supplement: 43-46

When recovered from the follicle, horse oocytes may be categorised as having either a compact or an expanded cumulus. Cumulus expansion is strongly associated with follicle atresia. Oocytes with expanded and compact cumuli have similar proportions in the germinal vesicle stage when recovered from the follicle. However, during in vitro culture, a higher proportion of oocytes with expanded cumuli mature, and they do so more quickly, than do oocytes with compact cumuli. Using Hoechst 33258 to label chromatin, in the germinal-vesicle stage horse oocytes can be divided into those in which the nucleus fluoresces diffusely (FN), and those in which the chromatin is condensed as a mass within the germinal vesicle (condensed chromatin; CC). The CC configuration is more common in oocytes with expanded rather than compact cumuli. The occurrence of the condensed chromatin configuration in oocytes with compact cumuli rises with increasing follicle size to the point that, in follicles >20 mm diameter, almost 80% of oocytes with compact cumuli have condensed chromatin. This suggests that the chromatin of fully grown oocytes condenses prior to the gonadotrophin stimulation that induces ovulation. The number of oocytes maturing in vitro correlates strongly with the presence of the condensed chromatin configuration at the beginning of culture for both cumulus types. This suggests that the condensed chromatin configuration represents the meiotically competent oocyte. In contrast, FN oocytes appear to be meiotically incompetent, although 61% of oocytes from small, apparently viable follicles, have the FN configuration. This leads to the hypothesis that the FN configuration represents viable germinal vesicle stage oocytes that have yet to acquire meiotic competence. As oocytes achieve meiotic competence, the chromatin appears to condense to the CC configuration. This change occurs during growth of the preovulatory follicle but it can also occur during follicular atresia. Information about the inherent meiotic competence of different populations of oocytes will assist in the selection of oocytes for experiments involving in vitro maturation and fertilisation in equids.


PMID: 9593526

Other references

Eggleton, R.A.; Foudoulis, C.; Varkevisser, D., 1987: Weathering of basalt: Changes in rock chemistry and mineralogy. The weathering of eastern Australian basalts, sampled from the rounded, hard, core-stone to the rind of softer weathered material, has been examined by bulk chemical analyses, thin section petrography, electron microprobe, and X-ray powder diffrac...

Lindsay F.N.; Bolge L.L.; Carr M.J.; Feigenson M.D., 2004: Geochemistry of Concepcion and Maderas volcanoes, Nicaragua, Central America. Eos, Transactions, American Geophysical Union 85(47, Suppl

Harrington, J.; Hansen, B.M.; Luszcz, S.H.; Seager, S.; Deming, D.; Menou, K.; Cho, J.Y-K.; Richardson, L.Jeremy., 2006: The phase-dependent infrared brightness of the extrasolar planet upsilon Andromedae b. The star upsilon Andromedae is orbited by three known planets, the innermost of which has an orbital period of 4.617 days and a mass at least 0.69 that of Jupiter. This planet is close enough to its host star that the radiation it absorbs overwhel...

Mares, P.; Tvrzicka, E.; Skorepa, J., 1979: Automated quantitative gas liquid chromatography of intact lipids 2. accuracy precision and reproducibility of results. The effect of various factors on precision and accuracy of the gas chromatographic determination of neutral lipids was studied in the concentration range where the correction factors are dependent on amount analyzed. The mutual effect of individua...

Henin S., 1968: Culture without labor. C R Seances Acad Agr Fr 54(2): 126-133

Hawley, C.E.; Falkler, W.A., 1978: The anti complementary activity of lipo poly saccharide preparations and sonicates from a strain of fusobacterium nucleatum. A complement [c] consumption [cc] assay was employed to test the consumption of guinea pig complement (GPC) by different sonicate and lipopolysaccharide (LPS) preparations obtained from Fusobacterium polymorphum. The consumption of normal GPC was...

Frazier L.W., 1985: In vitro acidification of mucosal fluid by the skin of rana pipiens. Federation Proceedings 44(3): 644

Haranczyk C., 1978: Krakow Paleozoic telluric province. Przeglad Geologiczny 6): 337-343

Jensen, V.B.; Harty, J.T.; Jones, B.D., 1998: Interactions of the invasive pathogens Salmonella typhimurium, Listeria monocytogenes, and Shigella flexneri with M cells and murine Peyer's patches. Invasive enteric bacteria must pass through the intestinal epithelium in order to establish infection. It is becoming clear that a common target for intestinal mucosa penetration is the specialized epithelial cell of Peyer's patches, the M ce...

Stoĭchev, I.I.; Stoianov, I.S.; Petkova-Bocharova, T.K.; Chernozemski, I.N.; Nikolov, I.G., 1978: Malignant tumors in a region of endemic nephropathy. In villages with endemic nephropathy (EN) high incidence and mortality rates of some urinary system tumors are reported. Age-adjusted incidences of renal pelvic and ureteral neoplasms were 46/10(5) in females and 27/10(5) in males; for urinary bla...