Follicular atresia in pigs: measurement and physiology.

Guthrie, Helen A.; Grimes, Randall W.; Cooper, Bret; Hammond, James M.

doi:10.2527/1995.7392834x

Cited by 76 publications

(72 citation statements)

References 32 publications

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“…However, regulating the release of pituitary hormones is not the only role of GnRH, because in gilts immunised against GnRH the follicles are not able to grow over 1 mm in diameter, even after PMSG administration (Esbenshade, 1987). The concentration of FSH decreases at about the 5th day, and at the same time an elevated level of follicular atresia is observed (Guthrie et al, 1995) (Fig. 1D, E).…”

Section: Folliculogenesis In Cyclic Giltsmentioning

confidence: 93%

“…The number of atretic follicles rises up to 50% on day 7. Between days 7 and 15 of the oestrous cycle the percentage of atretic follicles fluctuates between 12 and 73% (Guthrie et al, 1995). This means that follicles grow in groups with intensification of development at the same time, and then atresia follows steadily, suggesting a kind of regularity (Guthrie et al, 1995).…”

Section: Folliculogenesis In Cyclic Giltsmentioning

confidence: 99%

“…The most important event during the recruitment process is the synthesis of FSH receptors by small follicles, which enables the latter to grow over 1 mm in diameter (Guthrie et al, 1995). During the periovulatory period a surge of FSH is observed, and elevated concentrations of that hormone are maintained until about day 4 or 5 of the oestrous cycle, stimulating the development of small and medium follicles and reducing atresia (Knox et al, 2003) (Fig.…”

Section: Folliculogenesis In Cyclic Giltsmentioning

confidence: 99%

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Physiological mechanisms of ovarian follicular growth in pigs — A review

Schwarz

Kopyra

Nowicki

2008

Acta Veterinaria Hungarica

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Follicular growth after antrum formation is determined by folliclestimulating hormone (FSH). Only two ways are possible for recruited follicles, continuing development or atresia. In gilts, intensive ovarian follicular growth begins between 60 and 100 days of age, and fluctuations of the ovarian morphological status last about 20 days; however, at that time there are no really large follicles. Final follicular development is under luteinising hormone (LH) control; this is why the attainment of puberty is related to an increase in serum oestradiol to a level that causes a preovulatory surge of this gonadotropin. The pool of follicles at the beginning of the oestrous cycle is about 30-40, most of which are small (< 3 mm) and growing. Then, the pool of follicles increases to about 80 in the mid-luteal phase but about 50 of them are small and 30 are medium sized (3-6.9 mm). Some of these follicles are in the growing phase, but some are atretic. Between days 7 and 15 of the oestrous cycle the percentage of atretic follicles fluctuates between 12 and 73%. At that time there are no large (> 7 mm) follicles because of the suppressing effect of progesterone. The number of small follicles declines after luteolysis. From the pool of medium follicles, large follicles are selected under the influence of LH, but about 70% of the medium-sized follicles become atretic. Because of the long-lasting selection process there is a significant heterogeneity in the diameter of large follicles in oestrus. However, the number of follicles correlates with the number of corpora lutea after ovulation. Individual follicular development and the relationship between follicles are still poorly known. The use of ultrasonography may give a closer insight into these phenomena.

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Section: Folliculogenesis In Cyclic Giltsmentioning

confidence: 93%

Section: Folliculogenesis In Cyclic Giltsmentioning

confidence: 99%

Section: Folliculogenesis In Cyclic Giltsmentioning

confidence: 99%

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Physiological mechanisms of ovarian follicular growth in pigs — A review

Schwarz

Kopyra

Nowicki

2008

Acta Veterinaria Hungarica

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“…This study was followed in 1991 by two reports linking apoptosis to the process of follicular atresia in three different vertebrate species in vivo (Hughes and Gorospe, 1991;Tilly et al, 1991), with both studies relying on the occurrence of oligonucleosome formation as an indicator of apoptotic death. With the interest in apoptosis and the ovary refueled by these investigations, the past several years have seen an exponential increase in the number of publications documenting the occurrence of apoptosis in granulosa cells during atresia in all animal species studied to date (reviewed in: Guthrie et al, 1995;Tilly, 1996;Tilly and Ratts, 1996). In addition, many studies utilizing cultured granulosa cells or intact follicles have identified important roles for a wide spectrum of endocrine, paracrine and autocrine factors, such as gonadotropins (Tilly et al, 1992Chun et al, 1994;Tilly and Tilly, 1995), growth factors (Tilly et al, 1992Chun et al, 1994;Luciano et al, 1994), and neuropeptides (Flaws et al, 1995a), in regulating granulosa cell apoptosis during the later stages of follicular development.…”

Section: Apoptosis In the Ovary: A Brief Historical Accountmentioning

confidence: 99%

The genes of cell death and cellular susceptibility to apoptosis in the ovary: a hypothesis

Tilly

Perez

1997

Cell Death Differ

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Recent advances in the field of cell death, primarily derived from gene-transfer experiments and manipulation of tumor cell lines in vitro, have identified key genes responsible for determining whether or not a given cell will initiate apoptosis. However, comparatively less is known of the role that the products of these genes play in physiological settings of cell death. In the ovary, a tremendous level of normal cell death takes place in the germline throughout the later stages of fetal development. This process is responsible for setting the absolute number of oocytes (`eggs') available for subsequent development and ovulation during adult life. Interestingly, death remains the fate of the vast majority of oocytes that survive the waves of attrition during fetal life and are endowed in the post-natal ovary as primordial follicles. This pool of oocytes is lost indirectly as a consequence of the death of the somatic (granulosa) cells that, in the case of a small percentage of the total follicles, support and nourish the oocyte until its release at ovulation. Due to the magnitude of cell death that occurs normally within the female gonad during both fetal development and post-natal life, the ovary has proven to be an excellent model to study the role of cell death genes in a physiological setting of endocrine-regulated apoptosis.It is now known that a diverse spectrum of pro-and antiapoptosis susceptibility genes, including members of the bcl-2 and CASP (ced-3/Ice) gene families, are expressed in germ cells and/or somatic cells of the ovary. Many, but not all, of these genes are regulated by specific survival factors, such as gonadotropins and growth factors, and changes in the temporal patterns of cell death gene expression suggest an intimate association exists between the products of these genes and activation of cellular suicide. Moreover, pathological oocyte destruction, such as that triggered by exposure of female germ cells to chemotherapeutic compounds or environmental toxicants, may also be dependent upon genedriven apoptosis. As such, this review will discuss data supporting the hypothesis that the susceptibility of ovarian cells to death induction is dependent upon the pattern of cell death gene expression occurring within those cells prior to and/or concomitant with receipt of the stimulus for apoptosis. Elucidation of the relationship between germ cell loss and cell death genes may allow future intervention into the process of oocyte depletion associated with normal and pathophysiological reproductive senescence.

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“…At the biochemical basis atresia follicular cells are aromatase activity loss and the production of estradiol and the reduced secretion of steroid hormones [4], [33].…”

Section: Physiological Basis Of Folliculogenesis In Mammalsmentioning

confidence: 99%

Characteristic of factors influencing the proper course of folliculogenesis in mammals

Rybska

Knap

Jankowski

et al. 2018

Medical Journal of Cell Biology

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Folliculogenesis is the process of ovarian follicle formation,, taking presence during foetal period. During the follicular development, oogoniums undergo meiosis and oocytes are formed. In the ovaries of new born sows, primary and secondary follicles are present and, 90 days after birth, tertiary follicles appear. During development in the ovarian follicles growth of granulosa cells and differentiation of the thecal cells can be observed. A cavity filled with follicular fluid appears. Granulosa cells are divided into: mural cells and corona radiata, which together with the oocyte form the cumulus oophorus. Corona radiata cells, mural layers and oolemma contact each other by a network of gap junctions. Secreted from the pituitary gland, FSH and LH gonadotropin hormones act on receptors located in granular and follicular cells. In the postnatal life tertiary follicles and Graafian follicles are formed. When the follicle reaches a diameter of 1 mm, further growth depends on the secretion of gonadotropins. Mature ovarian follicles produce: progestins, androgens and oestrogens. The growth, differentiation and steroidogenic activity of ovarian follicles, in addition to FSH and LH, is also affected by prolactin, oxytocin, steroid and protein hormones, numerous proteins from the cytokine and interleukin family, metabolic hormones like insulin, glucocorticoids, leptin, thyroid hormones and growth hormones. Despite numerous studies, many processes related to folliculogenesis have not been discovered Learning the mechanisms regulating reproductive processes would allow to easily distinguish pathological processes and discover more and more genes and mechanisms of their expression in cells that build ovarian follicles. Running title: regulation of folliculogenesis

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Follicular atresia in pigs: measurement and physiology.

Cited by 76 publications

References 32 publications

Physiological mechanisms of ovarian follicular growth in pigs — A review

Physiological mechanisms of ovarian follicular growth in pigs — A review

The genes of cell death and cellular susceptibility to apoptosis in the ovary: a hypothesis

Characteristic of factors influencing the proper course of folliculogenesis in mammals

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