Morphology and Biochemistry of Ovulation Morfologia e bioquímica da ovulação

Abstract The process of ovulation involves multiple and iterrelated genetic, biochemical, and morphological events: cessation of the proliferation of granulosa cells, resumption of oocyte meiosis, expansion of cumulus cell-oocyte complexes, digestion of the follicle wall, and extrusion of the metaphase-II oocyte. The present narrative review examines these interrelated steps in detail. The combined or isolated roles of the folliclestimulating hormone (FSH) and luteinizing hormone (LH) are highlighted. Genes indiced by the FSH genes are relevant in the cumulus expansion, and LH-induced genes are critical for the resumption ofmeiosis and digestion of the follicle wall. A nonhuman model for follicle-wall digestion and oocyte release was provided.

Resumo O processo de ovulação envolve modificações genéticas, bioquímicas e morfológicas múltiplas e interrelacionadas: suspensão da proliferação das células da granulosa, reinício da meiose do oócito, expansão das células do complexo cumulus-oócito, digestão da parede folicular, e extrusão do oócito. Esta revisão narrativa examina em detalhes cada um desses eventos e os principais genes e proteínas envolvidos. Mais importante, a ação combinada ou isolada do hormônio folículo-estimulante (HFE) e do hormônio luteinizante (HL) é destacada. Detalha-se o papel do HFE na expansão do cumulus e do HL na digestão da parede folicular, permitindo a extrusão do oócito na superfície ovariana. Proveu-se um modelo não humano para explicar a digestão da parede folicular.

Electrophysiological responses to different follicle-stimulating hormone isoforms on human cumulus oophorus cells: preliminary results / Respostas eletrofisiológicas a diferentes isoformas de FSH em células humanas do cumulus oophorus: resultados preliminares

Abstract Objective The aim of the present study was to provide a better understanding of the specific action of two follicle-stimulating hormone (FSH) isoforms (β-follitropin and sheep FSH) on the membrane potential of human cumulus cells. Methods Electrophysiological data were associated with the characteristics of the patient, such as age and cause of infertility. The membrane potential of cumulus cells was recorded with borosilicate microelectrodes filled with KCl (3 M) with tip resistance of 15 to 25 MΩ. Sheep FSH and β-follitropin were topically administered onto the cells after stabilization of the resting potential for at least 5 minutes. Results In cumulus cells, the mean resting membrane potential was - 34.02 ± 2.04 mV (n = 14). The mean membrane resistance was 16.5 ± 1.8 MΩ (n = 14). Sheep FSH (4 mUI/mL) and β-follitropin (4 mUI/mL) produced depolarization in the membrane potential 180 and 120 seconds after the administration of the hormone, respectively. Conclusion Both FSH isoforms induced similar depolarization patterns, but β-follitropin presented a faster response. A better understanding of the differences of the effects of FSH isoforms on cell membrane potential shall contribute to improve the use of gonadotrophins in fertility treatments.

Resumo Objetivo O objetivo do presente estudo foi fornecer uma melhor compreensão da ação específica de duas isoformas de hormônio folículo estimulante (FSH, sigla em inglês) (β-folitropina e FSH ovino) no potencial de membrana de células do cumulus oophorus humanas. Métodos Dados eletrofisiológicos foram associados às características da paciente, como idade e causa da infertilidade. O potencial de membrana das células do cumulus foi registrado com microeletrodos de borossilicato preenchidos com KCl (3 M) com uma resistência de 15 a 25 MΩ. O FSH ovino e a β-folitropina foram administrados topicamente nas células após a estabilização do potencial de repouso durante pelo menos 5 minutos. Resultados Nas células do cumulus, o potencial médio de membrana em repouso foi de -34,02 ± 2,04 mV (n = 14). A resistência média da membrana foi de 16,5 ± 1,8 MΩ (n = 14). O FSH ovino (4 mUI/mL) e a β-folitropina (4 mUI/mL) produziram despolarização no potencial de membrana 180 e 120 segundos após a aplicação do hormônio, respectivamente. Conclusão Ambas as isoformas de FSH induzem padrões de despolarização semelhantes, mas a β-folitropina apresentou uma resposta mais rápida. Uma melhor compreensão das diferenças dos efeitos das isoformas do FSH no potencial da membrana celular contribuirá para aprimorar o uso das gonadotrofinas no estímulo ovariano controlado e em protocolos de maturação oocitária in vitro.

Effect of ovarian morphology on in vitro oocyte recovery and quality, and certain follicular fluid steroids hormones concentrations in ewes

The present study was conducted to investigate the effects of ovarian morphology on oocyte quantity and quality, as well as on follicular fluid steroid hormones concentrations. Fifty pairs of ovaries were collected from Barbari ewes and grouped into right, left, CL bearing and non-CL bearing ovaries. The weight, length, width and thickness of the right, left, CL bearing and non-CL bearing ovaries were recorded. The follicles were classified according to their diameter into 3 groups; small [<2mm], medium [2-4mm] and large [>4mm] follicles. Oocytes were classified according to their morphology into 3 grades; COCS [Compact cumulus oocyte complexes], POCS [Partially invested with less than three layers of cumulus cells] and DO [denuded oocyte]. The concentrations of progesterone and estradiol 17 beta in the follicular fluid were estimated. Results indicated that, dimensions of both right and left ovaries were not significantly differed. However, the ovarian dimensions as well as their weights were significantly [P < 0.05] affected by the presence of CL, being higher in the CL bearing ovary. The average number of large follicles were significantly [P < 0.05] increased in the right ovary when compared to the left one. The recovered COCs number was found to be significantly higher [P < 0.05] in the right than left ovaries. A greater number of vesicular follicles and aspirated COCS were found in the non-CL bearing ovary than in the CL bearing ovary. The non CL bearing ovaries provide larger numbers as well as higher quality of COCs when compared to CL bearing ovaries and that the former can be used to collect good quality COCs for in vitro production of sheep embryos. The progesterone concentration of follicular fluid was significantly higher in CL- and non-CL bearing ovaries [27.75 and 12.33 ng/ml; P < 0.05, respectively]. Non-CL bearing ovaries had significantly [P < 0.05] higher concentration of estradiol 17beta than those found in CL bearing ovaries [22.10 vs.8.43 pg/ml, respectively]. It can be concluded that non-CL bearing ovaries provide a higher number as well as superior quality of COCs than those obtained from ovaries bearing CL suggesting that the ovaries without CL can be used to collect good quality of COCs in view of in vitro production of sheep embryos [IVP]