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Keywords = graafian follicle

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9 pages, 1375 KiB  
Review
Effects of Heat Stress on Follicular Physiology in Dairy Cows
by Fabio De Rensis, Roberta Saleri, Irina Garcia-Ispierto, Rex Scaramuzzi and Fernando López-Gatius
Animals 2021, 11(12), 3406; https://doi.org/10.3390/ani11123406 - 29 Nov 2021
Cited by 30 | Viewed by 4837
Abstract
Follicular organization starts during mid-to-late fetal life with the formation of primordial follicles. The bilateral interplay between the oocyte and adjoining somatic cells during follicular growth and ovulation may be sensitive to heat stress (HS). Mechanisms giving rise to pre-ovulatory temperature gradients across [...] Read more.
Follicular organization starts during mid-to-late fetal life with the formation of primordial follicles. The bilateral interplay between the oocyte and adjoining somatic cells during follicular growth and ovulation may be sensitive to heat stress (HS). Mechanisms giving rise to pre-ovulatory temperature gradients across reproductive tissues are mostly regulated by the pre-ovulatory follicle, and because the cooling of the gonads and genital tract depends on a counter-current transfer system of heat, HS may be considered a major factor impairing ovulation, fertilization and early embryo development. There is evidence of a long-lasting influence of HS on oogenesis and final follicular maturation. Follicular stages that are susceptible to HS have not been precisely determined. Therefore, the aim of this review was to describe the influence of HS during the staged follicular development in dairy cattle, from the activation of primordial follicles to ovulation. Some clinical prospects are also considered. Full article
(This article belongs to the Special Issue Advances in Dairy Cattle Reproduction)
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7 pages, 1189 KiB  
Review
Thermal Mechanisms Preventing or Favoring Multiple Ovulations in Dairy Cattle
by Fabio De Rensis, Giorgio Morini, Irina Garcia-Ispierto and Fernando López-Gatius
Animals 2021, 11(2), 435; https://doi.org/10.3390/ani11020435 - 8 Feb 2021
Cited by 4 | Viewed by 3231
Abstract
While cows are predominantly monovular, over the past 30 years the incidence of multiple ovulations and thus twinning has increased considerably alongside milk production. Multiple pregnancies are not desirable as they negatively affect the health of cows and the herd economy. Although causal [...] Read more.
While cows are predominantly monovular, over the past 30 years the incidence of multiple ovulations and thus twinning has increased considerably alongside milk production. Multiple pregnancies are not desirable as they negatively affect the health of cows and the herd economy. Although causal mechanisms associated with multiple ovulations have been extensively revised, the process of multiple ovulations is not well understood. Recent studies on the thermal biology of the reproductive system have shown how thermal mechanisms may prevent or favor multiple ovulations. This review focuses on this relationship between thermal dynamics and multiple pregnancies. Cooling of the pre-ovulatory follicle is able to regulate ovulation. In effect, pre-ovulatory local cooling of the female reproductive system favors male and female gamete maturation and promotes fertilization. Thermal stress is proposed here as a model of stress. Periods of high ambient temperature affect the processes of pre-ovulatory follicular cooling and multiple ovulations. While the ratio between unilateral and bilateral multiple pregnancies is normally close to one, under heat stress conditions, this ratio may be 1.4 favoring unilateral multiple pregnancies. A ratio approaching unity is here proposed as an indicator of cow wellbeing. Full article
(This article belongs to the Special Issue Therapeutics of Twin Pregnancies in Dairy Cattle)
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16 pages, 4062 KiB  
Article
GPx8 Expression in Rat Oocytes, Embryos, and Female Genital Organs During Preimplantation Period of Pregnancy
by Jozef Mihalik, Andrea Kreheľová, Veronika Kovaříková, Peter Solár, Iveta Domoráková, Andriana Pavliuk-Karachevtseva, Alena Hladová, Silvia Rybárová and Ingrid Hodorová
Int. J. Mol. Sci. 2020, 21(17), 6313; https://doi.org/10.3390/ijms21176313 - 31 Aug 2020
Cited by 7 | Viewed by 2892
Abstract
This study aimed to detect the presence of glutathione peroxidase 8 (GPx8) in rat during preimplantation period of pregnancy. Females were killed on first (D1), third (D3), and fifth (D5) day of pregnancy. The presence of GPx8 in embryos was detected under the [...] Read more.
This study aimed to detect the presence of glutathione peroxidase 8 (GPx8) in rat during preimplantation period of pregnancy. Females were killed on first (D1), third (D3), and fifth (D5) day of pregnancy. The presence of GPx8 in embryos was detected under the confocal microscope, the presence of GPx8 in genital organs was confirmed immunohistochemically, and the amount of GPx8 was determined using densitometry. We found that GPx8 is dispersed in the cytoplasm of oocytes, while after fertilization, it is concentrated in granules. From 4-cell stage till blastocyst, GPx8 reaction was found in the perinuclear region. In the ovary, GPx8 was seen in granulosa-lutein cells, in plasma of blood vessels, and inside Graafian follicles. In oviduct, GPx8 was detected in the plasma and in the extracellular matrix (ECM). Moreover, epithelial cells of isthmus were positive. In uterus, GPx8 was observed in the uterine glands, in the plasma, and in ECM. On D5, the enzyme disappeared from the uterine glands and appeared in fibroblasts. Densitometry revealed that the highest amount of GPx8 was on D1 and subsequently declined. To our knowledge, this is the first paper describing GPx8 presence in the oocytes, preimplantation embryos, and female genital organs in mammals. Our results improve the understanding of antioxidant enzymes presence during pregnancy in defense against oxidative stress, which is considered to be one of the main causes of infertility. Full article
(This article belongs to the Special Issue Redox Modulation: Restoring Homeostasis with Antioxidants)
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