Atresia folicular en peces teleósteos: Una revisión

Many fish species with economic importance have been heavily exploited, causing the collapse of their fisheries. For this reason, there have been attempts to cultivate fish species for commercial purposes, resulting in varying success. It has been observed that when some species are kept in captivity or under intensive exploitation in its natural environment, they present reproductive dysfunctions that leads to the appearance of follicular atresia. This process is scarcely studied in fish and the characterization by several authors shows differences in nomenclature and criteria that make even more difficult its understanding. The objective of this work is to present a literature review of follicular atresia in fish that will contribute to its understanding and study. The follicular atresia is a degenerative process observed in some oocytes that can occur at any time of its development. The presence of follicular atresia has been associated with normal degenerative conditions due to seasonal changes in the gonadal activity, health disorders or inadequate management conditions in fish culture. It has been suggested that this process is a mechanism that allows the recycling of components and energy. However, in certain species such as puye (Galaxias maculatus) and cutthroat trout (Salmo clarki), among others, it has been noted the presence of follicular atresia with pathological characteristics, in which the yolk reabsorption does not occur causing the hardening of the more developed follicles that leads finally to the female death.Muchas especies de peces de importancia económica han sido intensamente explotadas, provocando el colapso de sus pesquerías. Por este motivo, en algunas de estas especies se han hecho intentos por lograr cultivar individuos con fines comerciales, obteniendo relativo éxito. Se ha observado que cuando algunas especies son mantenidas en cautiverio o bajo intensa presión de explotación en su medio natural presentan disfunciones reproductivas que conducen a la aparición de atresia folicular. Este es un proceso poco estudiado en peces y la caracterización realizada por varios autores, arroja diferencias de criterios y nomenclatura que dificultan aún más su comprensión. El objetivo de la presente investigación es realizar una revisión bibliográfica de la atresia folicular en peces y contribuir a su comprensión y estudio. La atresia folicular es un proceso degenerativo observado en algunos oocitos en cualquier momento de su desarrollo. La aparición de atresia folicular se ha relacionado con condiciones degenerativas normales debido a cambios estacionales en la actividad gonadal, afecciones sanitarias, o bien, a condiciones de manejo inadecuadas en peces mantenidos en cultivo. Este proceso se ha postulado como un mecanismo que permite reciclar componentes y energía. Sin embargo, en especies como el puye (Galaxias maculatus), la trucha garganta cortada (Salmo clarki), entre otras, se ha observado la presencia de una atresia folicular con características patológicas, en la cual la reabsorción del vitelo no ocurre, causando el endurecimiento de los folículos más desarrollados, lo que puede conducir finalmente a la muerte de la hembra

Desarrollo de embriones de bovino obtenidos por fecundación in vitro cultivados con células oviductales o medio condicionado y transferidos a hembras receptoras

Se comparó el desarrollo in vitro de ovocitos obtenidos de ovarios de vaca de matadero, madurados, fecundados y cultivados in vitro bajo dos sistemas. Los ovocitos fueron cultivados en un medio de maduración a 39 °C, 5 % de CO2 y humedad relativa de 95 % durante 22 horas. Posteriormente, fueron incubados con espermatozoides seleccionados a través de una gradiente discontinua de Percoll. La tasa de maduración nuclear y fecundación fueron de 93,7 % (74/79) y 76,9 % (50/65) respectivamente. Un total de 252 ovocitos fecundados fueron cultivados in vitro. El porcentaje de desarrollo in vitro a las 2 días post-inseminación (embriones de 4-8 células) fue de 62,7 % (64/102) para los cigotos cultivados con células oviductales y de 67 % (100/150) para los cultivados en medio condicionado (P0,05). El porcentaje de desarrollo de mórulas fue de 17,6 % (18/102) para los cigotos cultivados con células oviductales y de 13,3 % (20/150) para los cultivados con medio condicionado (P0,05). Se obtuvo una tasa de desarrollo del 15,7 % (16/102) de blastocistos para aquellos cigotos cultivados con células oviductales. No se obtuvo blastocistos a partir de cigotos cultivados en medio condicionado. Cuatro blastocistos fueron transferidos a dos hembras receptoras. A los 42 y 57 días se encontró la presencia de un feto en cada hembraThe in vitro development of matured and fertilized bovine oocytes was compared between two culture systems. Oocytes were collected by aspiration of follicles of 3-8 mm in diameter using an 18g needle. After morphological selection the oocytes were incubated at 39 0C, 5 % C02 y 95 % relative humidity, during 22 hours. Afterwards, oocytes were incubated with spermatozoa selected by Percoll gradient system. The rate of nuclear maturation and fertilization was 93,7 % (74/79) and 76,9 % (50/65), respectively. A total of 252 zygotes were cultured, 102 with oviductal cells and 150 in conditioned medium. The in vitro development on day 2 of culture (4- or 8-cell embryos) was 62,7 % (64/102) for the zygotes co-cultured with oviductal cells and 66,7 % (100/150) for the zygotes cultured in conditioned medium. The development to the morula stage was 17,6 % (18/102) for the zygotes co-cultured with oviductal cells and 13,3 % (20/150) for the zygotes cultured in conditioned medium. A statiscally significant difference was not found in the development of 4, 8-cell embryos or morula. The development of embryos up to the blastocyst stage was 15,7 % (16/102) for the zygotes co-cultured with oviductal cells. Two blastocysts were transferred to the uterine horn ipsilateral to the CL in two recipients by non-surgical embryo transfer. Pregnancy was confirmed by ultrasonography at 42 and 57 days detecting the presence of one conceptus in each animal. This work has shown that in vitro inseminated of bovine oocytes with espermatozoa prepared with modified BO and co-cultured with oviductal cells, can develop to the blastocysts stage, unlike those that were cultured with conditioned medium. Finally, it is important to mention that this is the first communication in Chile of pregnancy after in vitro fertilization of bovine oocyte

Effect of ovarian superstimulation on COC collection and maturation in alpacas

The objective of the present study was to compare the ovarian follicular response, cumulus-oocyte complex (COC) collection rate, and maturational status of COC collected from alpacas subsequent to treatment with two different superstimulatory protocols. Alpacas (n = 7 per group) were treated with: (1) 200 mg of FSH im divided bid for 3 d, plus a single i.v. dose of 1000 IU hCG 24 h after the last FSH treatment, or (2) 1200 IU of eCG as a single i.m. dose, plus a single i.v. dose of 1000 IU of hCG on day 3 after eCG treatment (day 0 = start of superstimulatory treatment). At 20-24 h post-hCG treatment, the ovaries were surgically exposed and COC were collected by needle aspiration of all follicles ≥6 mm. The FSH and eCG treatment groups did not differ with respect to the number of follicles ≥6 mm at the time of COC collection (20.0 ± 7.5 versus 27.0 ± 3.3; P = 0.5), the number of COC collected (26.2 ± 8.4 versus 23.3 ± 3.7; P = 0.7), or the collection rate per follicle aspirated (89% versus 87%; P = 0.7). No differences were detected between FSH- and eCG-treated alpacas in the number of expanded COC collected per alpaca (11.5 ± 2.9 versus 8.8 ± 2.8; P = 0.54), the number of expanded COC in metaphase II (8.5 ± 1.9 versus 6.0 ± 2.1; P = 0.1), or the number of compact COC with ≥3 layers of cumulus cells (12.5 ± 4.3 versus 14.3 ± 2.6; P = 0.72). A greater proportion (P < 0.05) of compact COC collected after FSH treatment matured in vitro to the metaphase II stage than after eCG treatment. Eight expanded alpaca COC were fertilized in vitro with llama sperm, three of which were fixed and stained 18 h after exposure to sperm and five were cultured in vitro. Two of the three stained oocytes were in the pronuclear stage, and all five of the cultured oocytes developed to the two-cell and morula stages at 2 and 7 days, respectively, after in vitro fertilization. In summary, FSH and eCG treatments were equally effective for ovarian superstimulation and oocyte collection. Cumulus-oocyte complexes were collected from more than 80% of follicles aspirated during laparotomy. Nearly one third of the COC collected after superstimulation were in metaphase II, and more than 70% of the remaining COC progressed to metaphase II after in vitro maturation for 26 h, bringing the mean number of oocytes available for in vitro fertilization to 16 per alpaca. Preliminary results support the hypothesis that alpaca oocytes obtained after superstimulation in the absence of progesterone are developmentally competent since morulae developed from all five COC fertilized and cultured in vitro

In vitro fertilization and development of cumulus oocytes complexes collected by ultrasound-guided follicle aspiration in superstimulated llamas

The objective was to evaluate the developmental competence of cumulus-oocyte complexes (COC) collected by follicular aspiration in llamas treated with FSH or eCG. Llamas were assigned randomly to two groups (n = 16 per group) and treated, at the time of ovarian follicular wave emergence, with either: 1) 25 mg of FSH im, twice daily for 4 d; or 2) 1000 IU of eCG as a single i.m. dose. The start of gonadotropin treatment was considered Day 0. Both groups were given 5 mg of Armour Standard LH im on Day 6, and COC were collected by follicle aspiration on Day 7. Expanded COC collected from FSH- (n = 157) and eCG-treated llamas (n = 151) were fertilized in vitro using epididymal sperm, and presumptive zygotes were in vitro cultured in SOF medium for 8 d. The FSH and eCG treatment groups did not differ with respect to: the number of follicles 7 mm (16.0; 2.7 vs 14.0; 1.9, respectively; P = 0.5); the number of COC collected (11.5; 1.9 vs 9.7; 1.2; P = 0.4); the number of expanded COC (9.8; 1.4 vs 9.4; 1.2; P = 0.8); or the percentage of presumptive zygotes which developed into 2 to 8 cell stage embryos (65.3 vs 63.1), morulas (46.2 vs 42.5), or blastocysts (23.1 vs 20.5; P > 0.05). In conclusion, FSH and eCG treatments were equally effective for recovery of a high number of expanded COC which were used directly for in vitro fertilization. Furthermore, rate of embryo development was not significantly affected by the gonadotropin treatment used. © 2011 Elsevier Inc

Follicular atresia in teleost fish: a review

Many fish species with economic importance have been heavily exploited, causing the collapse of their fisheries. For this reason, there have been attempts to cultivate fish species for commercial purposes, resulting in varying success. It has been observed that when some species are kept in captivity or under intensive exploitation in its natural environment, they present reproductive dysfunctions that leads to the appearance of follicular atresia. This process is scarcely studied in fish and the characterization by several authors shows differences in nomenclature and criteria that make even more difficult its understanding. The objective of this work is to present a literature review of follicular atresia in fish that will contribute to its understanding and study. The follicular atresia is a degenerative process observed in some oocytes that can occur at any time of its development. The presence of follicular atresia has been associated with normal degenerative conditions due to seasonal changes in the gonadal activity, health disorders or inadequate management conditions in fish culture. It has been suggested that this process is a mechanism that allows the recycling of components and energy. However, in certain species such as puye (Galaxies maculatus) and cutthroat trout (Salmo clarki), among others, it has been noted the presence of follicular atresia with pathological characteristics, in which the yolk reabsorption does not occur causing the hardening of the more developed follicles that leads finally to the female death

Effect of ovarian superstimulation on COC collection and maturation in alpacas

The objective of the present study was to compare the ovarian follicular response, cumulus-oocyte complex (COL) collection rate, and maturational status of COC collected from alpacas subsequent to treatment with two different superstimulatory protocols. Alpacas (n=7 per group) were treated with: (1) 200 mg of FSH im divided bid for 3 d, plus a single i.v. dose of 1000IU hCG 24 h after the last FSH treatment, or (2) 1200IU of eCG as a single i.m. dose, plus a single i.v. dose of 1000IU of hCG on day 3 after eCG treatment (day 0 = start of superstimulatory treatment). At 20-24 h post-hCG treatment, the ovaries were surgically exposed and COC were collected by needle aspiration of all follicles >= 6 mm. The FSH and eCG treatment groups did not differ with respect to the number of follicles >= 6 mm at the time of COC collection (20.0 +/- 7.5 versus 27.0 +/- 3.3; P=0.5), the number of COC collected (26.2 +/- 8.4 versus 23.3 +/- 3.7; P=0.7), or the collection rate per follicle aspirated (89% versus 87%; P = 0.7). No differences were detected between FSH- and eCG-treated alpacas in the number of expanded COC collected per alpaca (11.5 +/- 2.9 versus 8.8 +/- 2.8; P=0.54), the number of expanded COC in metaphase II (8.5 +/- 1.9 versus 6.0 +/- 2.1; P = 0.1), or the number of compact COC with >= 3 layers of cumulus cells (12.5 +/- 4.3 versus 14.3 +/- 2.6; P=0.72). A greater proportion (P < 0.05) of compact COC collected after FSH treatment matured in vitro to the metaphase II stage than after eCG treatment. Eight expanded alpaca COC were fertilized in vitro with llama sperm, three of which were fixed and stained 18 h after exposure to sperm and five were cultured in vitro. Two of the three stained oocytes were in the pronuclear stage, and all five of the cultured oocytes developed to the two-cell and morula stages at 2 and 7 days, respectively, after in vitro fertilization. In summary, FSH and eCG treatments were equally effective for ovarian superstimulation and oocyte collection. Cumulus-oocyte complexes were collected from more than 80% of follicles aspirated during laparotomy. Nearly one third of the COC collected after superstimulation were in metaphase II, and more than 70% of the remaining COC progressed to metaphase 11 after in vitro maturation for 26 h, bringing the mean number of oocytes available for in vitro fertilization to 16 per alpaca. Preliminary results support the hypothesis that alpaca oocytes obtained after superstimulation in the absence of progesterone are developmentally competent since morulae developed from all five COC fertilized and cultured in vitro. (c) 2006 Elsevier B.V. All rights reserved

Distribution of GnRH and Kisspeptin Immunoreactivity in the Female Llama Hypothalamus

Llamas are induced non-reflex ovulators, which ovulate in response to the hormonal stimulus of the male protein beta-nerve growth factor (beta-NGF) that is present in the seminal plasma; this response is dependent on the preovulatory gonadotrophin-releasing hormone (GnRH) release from the hypothalamus. GnRH neurones are vital for reproduction, as these provide the input that controls the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary gland. However, in spontaneous ovulators, the activity of GnRH cells is regulated by kisspeptin neurones that relay the oestrogen signal arising from the periphery. Here, we investigated the organisation of GnRH and kisspeptin systems in the hypothalamus of receptive adult female llamas. We found that GnRH cells exhibiting different shapes were distributed throughout the ventral forebrain and some of these were located in proximity to blood vessels; sections of the mediobasal hypothalamus (MBH) displayed the highest number of cells. GnRH fibres were observed in both the organum vasculosum laminae terminalis (OVLT) and median eminence (ME). We also detected abundant kisspeptin fibres in the MBH and ME; kisspeptin cells were found in the arcuate nucleus (ARC), but not in rostral areas of the hypothalamus. Quantitative analysis of GnRH and kisspeptin fibres in the ME revealed a higher innervation density of kisspeptin than of GnRH fibres. The physiological significance of the anatomical findings reported here for the ovulatory mechanism in llamas is still to be determined

New insights of the role of beta-NGF in the ovulation mechanism of induced ovulating species

The type of stimuli triggering GnRH secretion has been used to classify mammalian species into two categories: spontaneous or induced ovulators. In the former, ovarian steroids produced by a mature follicle elicit the release of GnRH from the hypothalamus, but in the latter, GnRH secretion requires coital stimulation. However, the mechanism responsible for eliciting the preovulatory LH surge in induced ovulators is still not well understood and seems to vary among species. The main goal of this review is to offer new information regarding the mechanism that regulates coitus-induced ovulation. Analysis of several studies documenting the discovery of beta-NGF in seminal plasma and its role in the control of ovulation in the llama and rabbit will be described. We also propose a working hypothesis regarding the sites of action of beta-NGF in the llama hypothalamus. Finally, we described the presence of beta-NGF in the semen of species categorized as spontaneous ovulators, mainly cattle, and its potential role in ovarian function. The discovery of this seminal molecule and its ovulatory effect in induced ovulators challenges previous concepts about the neuroendocrinology of reflex ovulation and has provided a new opportunity to examine the mechanism(s) involved in the cascade of events leading to ovulation. The presence of the factor in the semen of induced as well as spontaneous ovulators highlights the importance of understanding its signaling pathways and mechanism of action and may have broad implications in mammalian fertility

In vitro maturation of cat oocytes obtained from females treated with Follicle Stimulating Hormone

The aim of this research was to evaluate the effect of Follicle Stimulating Hormone (FSH) treatment on quality and in vitro maturation potential of cumulus-oocyte complexes (COCs) recovered from domestic cats. Twenty-one mature cats were randomly assigned to two groups, FSH (n=9) and Control (n=12). Cats in FSH group were treated with 5 mg of Folltropin-V subcutaneously every 24 hours, for 4 consecutive days. Cats in Control group received 1 mL of sterile saline solution every 24 hours for 4 days. Ovaries were obtained surgically 24 hours after the end of the gonadotrophic treatment. Ovaries were then transported to the laboratory at 37 degrees C within 4 hours after surgery. COCs were recovered by slicing, and classified according to morphological features. Maturation medium was based on TCM-1199, and supplemented with 0.4% BSA, 1 mu L/mL FSH, 1 mu L/mL LH y 1 mu g/mL of 17 beta oestradiol, 50 mu g/mL gentamicin, 0.20 mM sodium pyruvate. The maturation period was of 24 hours under 38.5 degrees C, 5% CO2 and saturated humidity. After this period oocytes were denuded, fixed and stained to asses their maturational status. Oocytes were considered mature when it was observed the presence of metaphase 11 plate and the expulsion of the first polar body. An average of 10.6 +/- 3.6 and 7.1 +/- 2.8 excellent and good quality COCs were recovered from cats in FSH and Control group respectively (P <= 0.05). Twenty five point six percent (25.6%) and 17% of recovered COCs from FSH and Control group respectively were classified as excellent or good (P :5 0.05). In vitro maturation rate was of 73.6% and 49.4% for the FSH group and the control group respectively (P <= 0.05). It can be concluded that FSH treatment increases the number of excellent and good quality oocytes obtained from cats and that these oocytes present a higher in vitro maturation potencial

In vitro maturation of cat oocytes obtained from females treated with follicle stimulating hormone

El objetivo de este trabajo fue evaluar el efecto del tratamiento con hormona folículo estimulante (FSH) sobre la calidad y potencial de maduración in vitro (MIV) de ovocitos de gata. Veintiún gatas adultas fueron asignadas aleatoriamente a grupos de estudio. Grupo FSH (n = 9) 5 mg NIH/día de Foltropin-V por 4 días vía subcutánea y Grupo Control (n = 12) 1 mL de suero fisiológico por 4 días vía subcutánea. Los ovarios fueron obtenidos quirúrgicamente y transportados al laboratorio dentro de las 4 horas subsiguientes a 37° C. Los complejos cumulus-ovocito (CCOs) fueron obtenidos por rebanado ovárico, seleccionándose por criterios morfológicos aquellos considerados aptos para MIV. Se utilizó como medio de maduración TCM-199, BSA (0,4%), FSH (1µL/mL), LH (1µL/mL), 17β estradiol (1µg/mL), gentamicina (50 µg/mL) y piruvato (0,2 mM). El cultivo se realizó durante 24 horas a 38,5° C con 5% de CO2. Posteriormente los ovocitos fueron denudados, fijados y teñidos para evaluar la maduración, considerándose maduros aquellos en metafase II. Se recuperaron en promedio por hembra 10,6 ± 3,6 y 7,1 ± 2,8 CCOs aptos para MIV en los grupos FSH y Control respectivamente (P ≤ 0,05). Se recuperó un 25,6% de CCOs aptos para MIV en el grupo FSH y 17% en el grupo Control (P ≤ 0,05). La tasa de MIV para el grupo FSH fue de un 73,6% versus 49,4% en el grupo Control (P ≤ 0,05). Se concluye que el tratamiento con FSH aumenta el número de CCOs aptos para MIV y que estos presentarían un mayor potencial de maduración.124 - 128BimestralThe aim of this research was to evaluate the effect of Follicle Stimulating Hormone (FSH) treatment on quality and in vitro maturation potential of cumulus-oocyte complexes (COCs) recovered from domestic cats. Twenty-one mature cats were randomly assigned to two groups, FSH (n=9) and Control (n=12). Cats in FSH group were treated with 5 mg of Folltropin-V subcutaneously every 24 hours, for 4 consecutive days. Cats in Control group received 1 mL of sterile saline solution every 24 hours for 4 days. Ovaries were obtained surgically 24 hours after the end of the gonadotrophic treatment. Ovaries were then transported to the laboratory at 37°C within 4 hours after surgery. COCs were recovered by slicing, and classified according to morphological features. Maturation medium was based on TCM-199, and supplemented with 0.4% BSA, 1µL/mL FSH, 1µL/mL LH y 1µg/mL of 17ß oestradiol, 50 µg/mL gentamicin, 0.20 mM sodium pyruvate. The maturation period was of 24 hours under 38.5°C, 5% CO2 and saturated humidity. After this period oocytes were denuded, fixed and stained to asses their maturational status. Oocytes were considered mature when it was observed the presence of metaphase II plate and the expulsion of the first polar body. An average of 10.6 ± 3.6 and 7.1 ± 2.8 excellent and good quality COCs were recovered from cats in FSH and Control group respectively (P ≤ 0.05). Twenty five point six percent (25.6%) and 17% of recovered COCs from FSH and Control group respectively were classified as excellent or good (P ≤ 0.05). In vitro maturation rate was of 73.6% and 49.4% for the FSH group and the control group respectively (P ≤ 0.05). It can be concluded that FSH treatment increases the number of excellent and good quality oocytes obtained from cats and that these oocytes present a higher in vitro maturation potencial