Follicle population, cumulus mucification, and oocyte chromatin configuration during the periovulatory period in the female dog

Reynaud, Karine; Lesegno, Christine Viaris de; Chebrout, Martine; Thoumire, Sandra; Chastant-Maillard, Sylvie

doi:10.1016/j.theriogenology.2009.07.006

Cited by 46 publications

(51 citation statements)

References 38 publications

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“…The presence of polyovular antral follicles of ovulatory diameter suggests that POFs do ovulate. An earlier study in dogs [27], in which more oocytes/embryos were collected in oviductal flushings than the number of corpora lutea counted, also supports the ovulation of polyovular follicles. In previous studies with the same mice lines as we used, it was reported that the number of ova released into the oviduct was considerably higher in the FL1 line than in the FL2 line.…”

Section: Discussionmentioning

confidence: 62%

Occurrence of Polyovular Follicles in Mouse Lines Selected for High Fecundity

Alm

Kuhlmann

Langhammer

et al. 2010

Journal of Reproduction and Development

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Abstract. The aim of this study was to evaluate the prevalence of follicles with more than one oocyte (polyovular follicles, POFs) in mouse lines selected for high fecundity. The ovaries of 18 mice, 6 each from 3 different lines, were examined to evaluate the number of POFs and the follicular histology. Polyovular follicles were observed in the two high fecundity breeds, FL1 and FL2, as well as in the unselected control line, DUKsi. The highest number of POFs per ovary (27.0 ± 7.2) was found in the FL1 line. The FL2 and DUKsi lines had 1.9 ± 0.7 and 0.6 ± 0.3 polyovular follicles per ovary, respectively. Most of the POFs contained 2 oocytes (>80%), but occasionally follicles containing up to 7 oocytes were observed. Follicles with more than 2 oocytes were observed in the FL1 line only. Key words: High fecundity, Mice, Polyovular follicles (POFs) (J. Reprod. Dev. 56: [449][450][451][452][453] 2010) n normal adult mouse ovaries, follicles contain a germ cell surrounded by one or more layers of granulosa cells, according to the follicle developmental stage. However, follicles with more than one oocyte are rarely found [1]. During initial development, multiple germ cells are present within the individualizing follicles, although in most cases, excess cells are eliminated and mammalian ovarian follicles contain only one germ cell per follicle. Follicles with more than one oocyte are referred to as multi oocyte follicles (MOFs) or polyovular follicles (POFs). They have been reported to occur in the ovaries of humans [2], primates [3], dogs [4,5], cats [6], goats [7] and mice [8]. In rats and mice, the incidence of POFs increases when the animals are exposed to estrogen analogs such as diethylstilbestrol, estradiol benzoate or genistein in a dose-dependent manner [9,10]. The POFs observed in mice and humans have been postulated to be remnants of oocyte clusters that did not separate, and which have become enclosed in follicles during neonatal primordial follicle assembly [2,10,11].Fecundity (the number of offspring per litter) can be related to an increase in the number of ova ovulated or in the efficiency of fertilization and embryo development. Booroola sheep have multiple offspring because of an increase in the number of follicles ovulated, which is related to the fecundity gene FecB, a mutation in bone morphogenetic protein receptor IB. The presence of FecB increases litter size by one or two extra lambs [12]. Polyovular follicles have been especially noted in bitches [13]. The presence of POFs could affect the number of oocytes recovered in assisted reproductive protocols and may also influence the ovulation rate and prolificity of these animals [5].Previous analysis of fecundity traits revealed that in high fecundity mouse lines (FL1, FL2), the number of ova ovulated is higher than the number of corpora lutea (CL) present. This is particularly evident in the FL1 line [14]. This observation suggests that individual follicles release more than one oocyte. The occurrence of polyovular follicles in specific strain...

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Section: Discussionmentioning

confidence: 62%

Occurrence of Polyovular Follicles in Mouse Lines Selected for High Fecundity

Alm

Kuhlmann

Langhammer

et al. 2010

Journal of Reproduction and Development

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“…5 mm whose follicular fluid contained more than 250 ng/ml E 2 were considered as preovulatory. Follicles that were 2-4 mm in diameter were considered as atretic (Reynaud et al 2009). …”

Section: Follicular Fluidsmentioning

confidence: 99%

IGF system and ovarian folliculogenesis in dog breeds of various sizes: is there a link?

Reynaud¹,

Chastant-Maillard²,

Batard³

et al. 2010

Journal of Endocrinology

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The IGF system plays a crucial role in ovarian folliculogenesis, and changes in IGF-binding protein (IGFBP) levels modulate IGF bioavailability. Data from various mammalian models suggest a link between body size, IGF1 in serum and female reproduction parameters. Among the vertebrate species, the dog exhibits the widest span in body height. Height is known to be positively correlated with the concentration of serum IGF1. In this work, the ovarian physiology of 40 bitches exhibiting a wide span of height, and breed type was investigated. IGF1, IGF2, IGFBP3, estradiol (E 2 ), and progesterone concentrations in plasma and preovulatory follicular fluid were quantified. A total of 455 follicles, 2-8 mm in diameter, were recovered at the preovulatory stage, measured, and punctured. Intrafollicular levels of IGF1 were positively correlated with plasma levels, and plasma IGF1 levels were positively correlated with both bitch height and weight. The concentrations were threefold higher in large dogs compared with small dogs. A positive correlation between intrafollicular and plasmatic IGFBP3 levels and a positive correlation between plasmatic IGFBP3 levels, and both height and weight of the bitches were observed. The number of preovulatory follicles and the diameter of the three largest follicles were positively correlated with bitch height. E 2 intrafollicular concentrations were higher in preovulatory follicles from small animals than in those from large animals. In conclusion, the strong variability in height between dogs appeared to be associated with dramatic differences in IGF1, and IGFBP3 levels, in both plasma and follicular fluid. These differences were associated with significant differences in some functional aspects of ovarian follicles.

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“…O presente trabalho, utilizando a microscopia de luz e fluorescência, pode ser considerado pioneiro no Brasil a utilizar a coloração Hoescht para a melhor visualização da cromatina e do nucléolo nessa espécie animal. Diversas técnicas podem ser usadas para descrever essa remodelação como a microscopia de luz, a microscopia eletrônica de transmissão e a microscopia confocal (DE LESEGNO et al, 2008;REYNAUD et al, 2009).…”

Section: Resultsunclassified

“…Assim, fica claro o envolvimento dos hormônios esteroides sobre os estágios da configuração da cromatina em VG conforme a progressão do ciclo estral, sendo os oócitos em VG-3 e o VG-4 mais capazes de atingir os estágios finais da maturação nuclear, possibilitando a obtenção de taxas de maturações mais elevadas, fertilização e consequente desenvolvimento embrionário. Reynaud et al (2009) descreveram três tipos de configurações de VG relacionadas com o pico de LH e a ovulação nas cadelas. A configuração difusa seria caracterizada por uma cromatina homogênea distribuída por todo o nucleoplasma, com aspecto difuso e presença de um ou ocasionalmente dois nucléolos.…”

Section: Resultsunclassified

“…Pode-se observar que o estágio de VG-1e VG-2 classificadas no presente trabalho são semelhantes à configuração difusa, o estágio VG-3 é similar à configuração parcialmente agrupada e o estágio VG-4 à configuração agrupada. Reynaud et al (2009) utilizando folículos pré-ovulatórios observaram 69% e 21% de oócitos, respectivamente, com cromatina parcialmente agrupada e totalmente agrupada. Destacaram, ainda, que há um grande indicativo de que ambas as configurações de cromatina, parcial e totalmente agrupada, são competentes para a retomada da meiose e que esta transição está associada não apenas com maturação nuclear, mas também com a maturação citoplasmática do oó-cito.…”

Section: Resultsunclassified

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Influência das fases de anestro e diestro sobre a configuração da cromatina em vesícula germinativa de oócitos caninos

Pereira

Bersano

Lopes

2013

Braz. J. Vet. Res. Anim. Sci.

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ResumoNa espécie canina as taxas de maturação oocitária são baixas e a porcentagem de oócitos que permanecem em estágio de vesícula germinativa (VG), independente das condições de cultivo, é alta. Durante a maturação oocitária, a VG sofre modificação e remodelamento da cromatina, que se manifesta por alterações na sua configuração e posicionamento. Assim, o objetivo deste trabalho é avaliar a configuração e o posicionamento da cromatina de oócitos em estágio de VG durante o anestro e diestro de cadelas. Os ovários de 33 fêmeas (20 cadelas em anestro e 13 em diestro) foram isolados, fatiados e os complexos cumulus-oócitos (COCs) foram submetidos à solução de hialuronidase 0,2% para a liberação das células do cumulus. Após esse processo, os oócitos selecionados foram corados, avaliados e apenas COCs grau 1 foram utilizados. De um total de 920 oócitos, 566 foram classificados como grau 1 e os estágios de configuração da cromatina identificados como VG-1, VG-2, VG-3 e VG-4. As alterações observadas na configuração da cromatina foram caracterizadas como transição de uma cromatina dispersa (VG-1, VG-2) para parcialmente condensada (VG-3) até atingir um estágio totalmente condensado (VG-4). Os dados analisados da configuração da cromatina mostraram uma diferença significativa entre as fases de anestro e diestro, com maior proporção de VG-1 e VG-2 durante o anestro e de VG-3 e VG-4 durante o diestro. Há necessidade de novos estudos para uma compreensão adequada da influência da configuração da cromatina de oócitos no estágio de VG na retomada da meiose e na competência meiótica do oócito. Palavras-chave:Oócito. Cromatina. Vesícula germinativa. Cadelas. AbstractIn canine specie, oocyte maturation rates are low and the percentage of oocytes that remain in the stage of germinal vesicle (GV) regardless of culture conditions is high. During maturation oocyte undergoes modification and the GV chromatin remodeling manifested by changes in the configuration and positioning. The objective of this work is to evaluate the configuration and positioning of chromatin of oocytes in GV stage during anestrus and diestrus bitches. The ovaries of 33 females (20 bitches in anestrous and 13 in diestrus) were isolated, sliced and only cumulus-oocyte complexes (COCs) grade 1 were subjected to solution of 0.2% hyaluronidase for release in cumulus cells. After this process, the selected oocytes were stained and evaluated. From a total of 920 oocytes, 566 were classified as grade 1 and the stages of chromatin configuration identified as GV-1, GV-2, GV-3 and GV-4. The observed changes in chromatin configuration been characterized as a transition dispersed chromatin (GV-1, GV-2) for partially condensed (GV-3) until it reaches a fully condensed stage (GV-4). The data analyzed from the chromatin configuration showed a significant difference between the stages with a higher proportion of GV-1 and GV-2 for the anoestrus and GV-3 and GV-4 during diestrus. There is need for further studies to be able to have a proper understanding of the influence of ch...

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Follicle population, cumulus mucification, and oocyte chromatin configuration during the periovulatory period in the female dog

Cited by 46 publications

References 38 publications

Occurrence of Polyovular Follicles in Mouse Lines Selected for High Fecundity

Occurrence of Polyovular Follicles in Mouse Lines Selected for High Fecundity

IGF system and ovarian folliculogenesis in dog breeds of various sizes: is there a link?

Influência das fases de anestro e diestro sobre a configuração da cromatina em vesícula germinativa de oócitos caninos

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