Effectiveness of near-infrared spectroscopy as a non-invasive tool to discriminate spectral profiles of in vitro cultured oocytes from goats

Abstract Here, we aimed to discriminate between the spectral profiles of spent culture media after oocyte in vitro maturation (IVM) and culture (IVC) from goats of different ages subjected to repeated hormonal treatments. The profiles were discriminated using near infrared (NIR) spectroscopy combined with multivariate methods. A total of 19 goats (young = 10; old = 9) were subjected to serial hormonal stimulation (HS) with gonadotropins. Cumulus oophorus complexes (COCs) were collected using laparoscopic ovum pick-up (LOPU) and subjected to IVM and parthenogenetic activation. The initial embryos were subjected to IVC. Spent culture media were collected after oocyte IVM and on day 2 of IVC and analyzed using NIR spectroscopy. NIR spectral data were interpreted through chemometric methods, such as principle component analysis (PCA) and partial least square discriminant analysis (PLS-DA). The results of PCA analysis clearly showed a separation in the spectral profiles between the experimental groups (HS sessions; young and old animals) both after IVM and IVC. Overall, the main absorption bands were attributed to the C-H group second overtone, first overtone of O-H and N-H, and C-H combinations and may serve as molecular markers. On the other hand, the spectral data obtained using PLS-DA models provided a better classification of the groups. The results showed the possibility of discriminating young and old groups as well as the three HS sessions with high specificity, sensitivity, and accuracy using NIR spectra. Thus, the culture medium analysis using NIR spectroscopy combined with multivariate methods indicated the dissimilarities between the groups and provided an insight into the in vitro development of goat oocytes. This technique serves as an efficient, objective, rapid, and non-invasive method to discriminate spectral profiles.

Effectiveness of near-infrared spectroscopy as a non-invasive tool to discriminate spectral profiles of in vitro cultured oocytes from goats

Here, we aimed to discriminate between the spectral profiles of spent culture media after oocyte in vitro maturation (IVM) and culture (IVC) from goats of different ages subjected to repeated hormonal treatments. The profiles were discriminated using near infrared (NIR) spectroscopy combined with multivariate methods. A total of 19 goats (young = 10; old = 9) were subjected to serial hormonal stimulation (HS) with gonadotropins. Cumulus oophorus complexes (COCs) were collected using laparoscopic ovum pick-up (LOPU) and subjected to IVM and parthenogenetic activation. The initial embryos were subjected to IVC. Spent culture media were collected after oocyte IVM and on day 2 of IVC and analyzed using NIR spectroscopy. NIR spectral data were interpreted through chemometric methods, such as principle component analysis (PCA) and partial least square discriminant analysis (PLS-DA). The results of PCA analysis clearly showed a separation in the spectral profiles between the experimental groups (HS sessions; young and old animals) both after IVM and IVC. Overall, the main absorption bands were attributed to the C-H group second overtone, first overtone of O-H and N-H, and C-H combinations and may serve as molecular markers. On the other hand, the spectral data obtained using PLS-DA models provided a better classification of the groups. The results showed the possibility of discriminating young and old groups as well as the three HS sessions with high specificity, sensitivity, and accuracy using NIR spectra. Thus, the culture medium analysis using NIR spectroscopy combined with multivariate methods indicated the dissimilarities between the groups and provided an insight into the in vitro development of goat oocytes. This technique serves as an efficient, objective, rapid, and non-invasive method to discriminate spectral profiles.(AU)

Impact of hypotensive action of angiotensin converting enzyme inhibitor on ovarian-intraovarian blood flow and follicles development in goats hormonally stimulated with repeated FSH-ECG treatment

Background: Recent evidence shows that the renin-angiotensin system (RAS) participates in important reproductiveprocesses, such as steroidogenesis, folliculogenesis, oocyte maturation and ovulation. Several studies have proposed touse an angiotensin-converting enzyme (ACE) as a RAS modulator, aiming to improve reproductive efficiency, however,the presence of the main components of this system in reproductive tissues still need to be further investigated, since thephysiological functions seem to be species-specific. The aim of this study was to assess the impact of enalapril-maleate,an ACE inhibitor, during repeated gonadotropins treatment on ovarian blood flow and follicular development in goats.Materials, Methods & Results: Twenty Anglo-Nubian cross-bred goats were equally grouped according to parity (n= 10/group): nulliparous and multiparous parity. In each group, five animals were randomly selected to receive 0.4 mg.kg-1 ofenalapril-maleate during 11 days of estrus synchronization and gonadotropins treatments. The other animals received thesame volume of saline solution. Estrus synchronization of all goats was made by intramuscular ad-ministration of PGF2αanalog, followed 48 h later by intravaginal insertion of a controlled internal drug release device. Forty-eight h after devicewithdrawal, a single dose of 60 mg of FSH plus 300 UI of eCG was administered and repeated every 4 days to complete 3treatments. Transrectal ultrasonography was performed using pulsed and color Doppler to evaluate Doppler velocimetricsparameters of the ovarian artery and intraovarian blood flow, respec-tively, and B-mode real-time ultrasound scanner toevaluate the follicular development. In the females treated with enalapril-maleate was observed a significant reduction ofsystolic and diastolic peak, without difference according to parity. In addition, in the third session of hor-monal stimulation,only the groups (nulliparous and multiparous) not treated with...(AU)

Impact of hypotensive action of angiotensin converting enzyme inhibitor on ovarian-intraovarian blood flow and follicles development in goats hormonally stimulated with repeated FSH-ECG treatment

Background: Recent evidence shows that the renin-angiotensin system (RAS) participates in important reproductiveprocesses, such as steroidogenesis, folliculogenesis, oocyte maturation and ovulation. Several studies have proposed touse an angiotensin-converting enzyme (ACE) as a RAS modulator, aiming to improve reproductive efficiency, however,the presence of the main components of this system in reproductive tissues still need to be further investigated, since thephysiological functions seem to be species-specific. The aim of this study was to assess the impact of enalapril-maleate,an ACE inhibitor, during repeated gonadotropins treatment on ovarian blood flow and follicular development in goats.Materials, Methods & Results: Twenty Anglo-Nubian cross-bred goats were equally grouped according to parity (n= 10/group): nulliparous and multiparous parity. In each group, five animals were randomly selected to receive 0.4 mg.kg-1 ofenalapril-maleate during 11 days of estrus synchronization and gonadotropins treatments. The other animals received thesame volume of saline solution. Estrus synchronization of all goats was made by intramuscular ad-ministration of PGF2αanalog, followed 48 h later by intravaginal insertion of a controlled internal drug release device. Forty-eight h after devicewithdrawal, a single dose of 60 mg of FSH plus 300 UI of eCG was administered and repeated every 4 days to complete 3treatments. Transrectal ultrasonography was performed using pulsed and color Doppler to evaluate Doppler velocimetricsparameters of the ovarian artery and intraovarian blood flow, respec-tively, and B-mode real-time ultrasound scanner toevaluate the follicular development. In the females treated with enalapril-maleate was observed a significant reduction ofsystolic and diastolic peak, without difference according to parity. In addition, in the third session of hor-monal stimulation,only the groups (nulliparous and multiparous) not treated with...

Fluido amniótico, alternativa eficiente para obtenção de células-tronco mesenquimais multipotentes / Amniotic fluid, efficient alternative to obtain multipotent mesenchymal stem cells

Na última década houve um crescente interesse na investigação quanto à presença de células-tronco no fluido amniótico, devido a facilidade de obtenção, isolamento e cultivo in vitro. Além disso, a utilização do fluido como fonte de células-tronco possibilita a obtenção de células com alto grau de indiferenciação e elevada taxa de proliferação in vitro e grande capacidade de diferenciação. Todas estas vantagens tornam o líquido amniótico uma fonte atrativa de células-tronco para utilização em biotecnologias reprodutivas, como a clonagem e transgênese, bem como ensaios clínicos e terapias celulares em animais para posterior utilização em seres humanos. Este artigo apresenta um panorama da pesquisa científica com células-tronco derivadas do fluido amniótico no mundo, a partir de levantamento bibliográfico de artigos científicos de pesquisadores brasileiros e estrangeiros.

In the last decade there has been a growing interest in investigation of presence of stem cells in amniotic fluid due to the ease of obtaining, isolating and in vitro culture. In addition, the use of amniotic fluid as a source of stem cells makes it possible to obtain cells with a high degree of indifferentiation and a high rate of in vitro proliferation and a great capacity for differentiation. All of these advantages make amniotic fluid an attractive source of stem cells for use in reproductive biotechnologies, such as cloning and transgenesis, as well as clinical trials in animals for further use in humans. This article presents a panorama of the scientific research with stem cells derived from amniotic fluid in the world, from a bibliographical survey of scientific articles of Brazilian and foreign researchers.

Fluido amniótico, alternativa eficiente para obtenção de células-tronco mesenquimais multipotentes / Amniotic fluid, efficient alternative to obtain multipotent mesenchymal stem cells

Na última década houve um crescente interesse na investigação quanto à presença de células-tronco no fluido amniótico, devido a facilidade de obtenção, isolamento e cultivo in vitro. Além disso, a utilização do fluido como fonte de células-tronco possibilita a obtenção de células com alto grau de indiferenciação e elevada taxa de proliferação in vitro e grande capacidade de diferenciação. Todas estas vantagens tornam o líquido amniótico uma fonte atrativa de células-tronco para utilização em biotecnologias reprodutivas, como a clonagem e transgênese, bem como ensaios clínicos e terapias celulares em animais para posterior utilização em seres humanos. Este artigo apresenta um panorama da pesquisa científica com células-tronco derivadas do fluido amniótico no mundo, a partir de levantamento bibliográfico de artigos científicos de pesquisadores brasileiros e estrangeiros.(AU)

In the last decade there has been a growing interest in investigation of presence of stem cells in amniotic fluid due to the ease of obtaining, isolating and in vitro culture. In addition, the use of amniotic fluid as a source of stem cells makes it possible to obtain cells with a high degree of indifferentiation and a high rate of in vitro proliferation and a great capacity for differentiation. All of these advantages make amniotic fluid an attractive source of stem cells for use in reproductive biotechnologies, such as cloning and transgenesis, as well as clinical trials in animals for further use in humans. This article presents a panorama of the scientific research with stem cells derived from amniotic fluid in the world, from a bibliographical survey of scientific articles of Brazilian and foreign researchers. (AU)

Espectroscopia NIR e análise multivariada aplicadas à identificação de grupos espectrais de células tronco derivadas do fluido amniótico de caprinos / NIR spectroscopy and multivariate analysis applied to the identification of spectrum groups of trunk cells derived from goats amniotic fluid

O objetivo deste trabalho foi desenvolver um modelo preditivo através de técnica multivariada para diferenciar meios de cultivo de células-tronco cultivadas in vitro e criopreservadas de acordo com os perfis de absorbância obtidas por NIR. Para tanto, foram coletados meios de cultivo de células-tronco oriundo do fluido amniótico de fetos caprinos, antes e após o processo de criopreservação por vitrificarão, e submetidos à análise pelo NIR. Foi possível estimar com alta acurácia o tratamento empregado nas amostras, gerando uma impressão digital dos meios de cultivo in vitro de células criopreservadas ou não.

The objective of this work was to develop a predictive model through a multivariate technique to differentiate culture media from stem cells cultured in vitro and cryopreserved according to the absorbance profiles obtained by NIR. For this purpose, culture media were collected from stem cells from the amniotic fluid of goat fetuses, before and after cryopreservation by vitrification, and submitted to NIR analysis. It was possible to estimate with high accuracy the treatment used in the samples, generating a fingerprint of in vitro culture media of cryopreserved cells or not.

Espectroscopia NIR e análise multivariada aplicadas à identificação de grupos espectrais de células tronco derivadas do fluido amniótico de caprinos / NIR spectroscopy and multivariate analysis applied to the identification of spectrum groups of trunk cells derived from goats amniotic fluid

O objetivo deste trabalho foi desenvolver um modelo preditivo através de técnica multivariada para diferenciar meios de cultivo de células-tronco cultivadas in vitro e criopreservadas de acordo com os perfis de absorbância obtidas por NIR. Para tanto, foram coletados meios de cultivo de células-tronco oriundo do fluido amniótico de fetos caprinos, antes e após o processo de criopreservação por vitrificarão, e submetidos à análise pelo NIR. Foi possível estimar com alta acurácia o tratamento empregado nas amostras, gerando uma impressão digital dos meios de cultivo in vitro de células criopreservadas ou não.(AU)

The objective of this work was to develop a predictive model through a multivariate technique to differentiate culture media from stem cells cultured in vitro and cryopreserved according to the absorbance profiles obtained by NIR. For this purpose, culture media were collected from stem cells from the amniotic fluid of goat fetuses, before and after cryopreservation by vitrification, and submitted to NIR analysis. It was possible to estimate with high accuracy the treatment used in the samples, generating a fingerprint of in vitro culture media of cryopreserved cells or not.(AU)

Efeito do DMSO e glicerol na criopreservação de células tronco mesenquimais derivadas de líquido amniótico de fetos caprinos / Effect of DMSO and glycerol in criopreservation of mesenquimial trunk cells derived from amniotic fluid of caprine fetus

O objetivo do estudo foi avaliar a viabilidade e taxa de proliferação de células-tronco mesenquimais (CTMs) derivadas do líquido amniótico (LA) após cultivo in vitro, e o efeito de dois agentes crioprotetores. Foram utilizadas 9 cabras prenhes. As amostras foram colhidas de fetos caprinos por laparotomia, e delas obtidos as (CTMs) e submetidas ao cultivo in vitro. Posteriormente, uma fração das células foi criopreservada em meio DMSO (dimetilsulfóxido) ou glicerol e vitrificadas para posterior avaliação da viabilidade. O meio DMSO promoveu melhores taxas de sobrevida celular preservando as características de pluripotencialidade e de replicação in vitro.

The objective of the study was to evaluate the viability and proliferation rate of mesenchymal stem cells (MTCs) derived from amniotic fluid (LA) after in vitro culture, and the effect of two cryoprotective agents. 9 pregnant goats were used. The samples were collected from goat fetuses by laparotomy, and from them (CTMs) were obtained and cultured in vitro. Subsequently, a fraction of the cells were cryopreserved in DMSO (dimethylsulfoxide) or glycerol medium and vitrified for further evaluation of viability. The DMSO medium promoted better cell survival rates while preserving the characteristics of pluripotency and replication in vitro.

Efeito do escore da condição corporal materna no desenvolvimento in vitro das células tronco mesenquimais do cordão umbilical de fetos caprinos / Effect of the score of maternal body condition in the in vitro development of the mesenquimal trunk cells in the umbilical cord of caprine fetes

O objetivo do trabalho foi avaliar o efeito do escore da condição corporal (ECC) materno sobre a capacidade de isolamento, expansão e caracterização de células-tronco mesenquimais (CTMs) derivadas do cordão umbilical de fetos caprinos. Para tanto, dezenove cabras mestiças adultas, pluríparas foram agrupadas de acordo com o ECC, atribuindo-se um escore de 1-5, (GB) grupo baixo com menor ECC, (2,3±0,1, GB, n = 9) e (GA) grupo alto com maior ECC (2,9±0,1, GA, n = 10). Durante o parto, fragmentos do cordão umbilical foram coletados e cultivados in vitro e avaliados a taxa de proliferação celular. Nenhum efeito significativo do ECC foi encontrado para os parâmetros considerados.

The objective of this study was to evaluate the effect of the maternal body condition score (ECC) on the ability to isolate, expand and characterize mesenchymal stem cells (MTCs) derived from the umbilical cord of goat fetuses. Nineteen crossbred adult crossbred goats were grouped according to ECC, giving a score of 1-5 (GB) low group with lower ECC, (2.3±0.1, GB, n = 9 ) and (GA) high group with higher ECC (2.9±0.1, GA, n = 10). During delivery, umbilical cord fragments were collected and cultured in vitro and the rate of cell proliferation was evaluated. No significant effect of ECC was found for the parameters considered.

Efeito do DMSO e glicerol na criopreservação de células tronco mesenquimais derivadas de líquido amniótico de fetos caprinos / Effect of DMSO and glycerol in criopreservation of mesenquimial trunk cells derived from amniotic fluid of caprine fetus

O objetivo do estudo foi avaliar a viabilidade e taxa de proliferação de células-tronco mesenquimais (CTMs) derivadas do líquido amniótico (LA) após cultivo in vitro, e o efeito de dois agentes crioprotetores. Foram utilizadas 9 cabras prenhes. As amostras foram colhidas de fetos caprinos por laparotomia, e delas obtidos as (CTMs) e submetidas ao cultivo in vitro. Posteriormente, uma fração das células foi criopreservada em meio DMSO (dimetilsulfóxido) ou glicerol e vitrificadas para posterior avaliação da viabilidade. O meio DMSO promoveu melhores taxas de sobrevida celular preservando as características de pluripotencialidade e de replicação in vitro.(AU)

The objective of the study was to evaluate the viability and proliferation rate of mesenchymal stem cells (MTCs) derived from amniotic fluid (LA) after in vitro culture, and the effect of two cryoprotective agents. 9 pregnant goats were used. The samples were collected from goat fetuses by laparotomy, and from them (CTMs) were obtained and cultured in vitro. Subsequently, a fraction of the cells were cryopreserved in DMSO (dimethylsulfoxide) or glycerol medium and vitrified for further evaluation of viability. The DMSO medium promoted better cell survival rates while preserving the characteristics of pluripotency and replication in vitro.(AU)

Efeito do escore da condição corporal materna no desenvolvimento in vitro das células tronco mesenquimais do cordão umbilical de fetos caprinos / Effect of the score of maternal body condition in the in vitro development of the mesenquimal trunk cells in the umbilical cord of caprine fetes

O objetivo do trabalho foi avaliar o efeito do escore da condição corporal (ECC) materno sobre a capacidade de isolamento, expansão e caracterização de células-tronco mesenquimais (CTMs) derivadas do cordão umbilical de fetos caprinos. Para tanto, dezenove cabras mestiças adultas, pluríparas foram agrupadas de acordo com o ECC, atribuindo-se um escore de 1-5, (GB) grupo baixo com menor ECC, (2,3±0,1, GB, n = 9) e (GA) grupo alto com maior ECC (2,9±0,1, GA, n = 10). Durante o parto, fragmentos do cordão umbilical foram coletados e cultivados in vitro e avaliados a taxa de proliferação celular. Nenhum efeito significativo do ECC foi encontrado para os parâmetros considerados.(AU)

The objective of this study was to evaluate the effect of the maternal body condition score (ECC) on the ability to isolate, expand and characterize mesenchymal stem cells (MTCs) derived from the umbilical cord of goat fetuses. Nineteen crossbred adult crossbred goats were grouped according to ECC, giving a score of 1-5 (GB) low group with lower ECC, (2.3±0.1, GB, n = 9 ) and (GA) high group with higher ECC (2.9±0.1, GA, n = 10). During delivery, umbilical cord fragments were collected and cultured in vitro and the rate of cell proliferation was evaluated. No significant effect of ECC was found for the parameters considered.(AU)

Progesterone and Follicle Stimulating Hormone interact and promote goat preantral follicles survival and development in vitro / Progesterona e Hormônio Folículo-Estimulante interagem e promovem a sobrevivência e o desenvolvimento in vitro de folículos pré-antrais caprinos

We investigated the effects of progesterone and follicle stimulating hormone (FSH) on survival and growth of caprine preantral follicles. Pieces of ovarian tissue were cultured for 1 or 7 days in minimum essential medium (MEM) alone or containing progesterone (1, 2.5, 5, 10 or 20ng/mL), FSH (50ng/mL) or the interaction between progesterone and FSH. Fresh (non-cultured control) and cultured ovarian tissues were processed for histological and ultrastructural studies. After 7 days the addition of FSH to all progesterone concentrations maintained the percentage of normal follicles similar to fresh control. At day 7 of culture, a higher percentage of developing follicles was observed only in 2.5ng/ml of progesterone associated with FSH or 10ng/ml of progesterone alone when compared with control. From day 1 to day 7 of culture, a significant increase in the percentage of developing follicles was observed in MEM and 2.5ng/ml of progesterone + FSH. In addition, after 7 days, in all treatments, there was a significant increase in follicular diameter when compared with control, except for MEM alone and in 5ng/ml of progesterone + FSH or 10ng/ml of progesterone alone. Ultrastructural studies confirmed follicular integrity after 7 days of culture in 2.5ng/ml of progesterone with FSH. In conclusion, this study demonstrated that the interaction between progesterone and FSH maintains ultrastructural integrity, stimulates primordial follicles activation and further growth of cultured caprine preantral follicles.(AU)

Este trabalho verificou os efeitos da progesterona e do hormônio folículo-estimulante (FSH) na sobrevivência e no crescimento de folículos pré-antrais caprinos. Fragmentos de tecido ovariano foram cultivados por 1 ou 7 dias em Meio Essencial Mínimo (MEM) sozinho ou contendo progesterona (1, 2.5, 5, 10 ou 20ng/mL), FSH (50ng/mL) ou a combinação entre esses dois hormônios. O tecido fresco (controle não-cultivado) e o cultivado foram processados para análise histológica e ultra-estrutural. Após 7 dias a adição de FSH a todas as concentrações de progesterone manteve o percentual de folículos normais similar ao controle fresco. No dia 7 de cultivo, um alto percentual de folículos em desenvolvimento foi observado somente no tratamento com 2,5ng/ml de progesterona associada ao FSH ou com 10ng/ml de progesterona sozinha, em relação ao controle fresco. Do dia 1 para o dia 7 de cultivo, um aumento significativo no percentual de folículos em desenvolvimento foi observado no MEM sozinho e adicionado de 2,5ng/ml de progesterona + FSH. Além disso, após 7 dias, em todos os tratamentos, houve um aumento significativo no diâmetro folicular em relação ao controle, exceto nos tratamentos com MEM sozinho, 5ng/ml de progesterona + FSH ou 10ng/ml de progesterona sozinha. A análise ultra-estrutural confirmou a integridade follicular após 7 dias de cultivo no tratamento com 2,5ng/ml de progesterona + FSH. Em conclusão, este estudo demonstrou que a interação entre progesterona e FSH mantém a integridade ultra-estrutural, estimula a ativação de folículos primordiais e o posterior crescimento de folículos pré-antrais caprinos cultivados in vitro.(AU)

Avanços no isolamento e sistemas de cultivo de folículos pré-antrais / Advances in isolation and culture systems of preantral follicles

Os folículos pré-antrais presentes no córtex ovariano representam cerca de 95% de toda a população folicular e podem ser crescidos e maturados in vitro, visando a obtenção posterior de oócitos maturos e competentes, os quais poderão ser utilizados nas diversas biotécnicas da reprodução aplicadas aos animais domésticos. Os estudos relacionados com a foliculogênese podem ser feitos in vivo, através da análise de expressão de genes ou proteínas que estão presentes no ovário, e ainda in vitro com a utilização de diferentes sistemas, onde os folículos podem ser cultivados in situ ou isolados. Deste modo, neste trabalho foram abordados os diferentes métodos de isolamento e sistemas de cultivo in vitro empregados para a manutenção da integridade estrutural e desenvolvimento de folículos pré-antrais.

The preantral follicles enclosed in ovarian cortex represent about 95% of the entire follicular population and can be grown and matured in vitro in order to obtain mature and competent oocytes, which may be used in various reproductive biotechnologies applied to domestic animals. Studies related to folliculogenesis can be performed in vivo, by analyzing the expression of genes or proteins that are present in the ovary, and also in vitro with the use of different systems, in which the follicles can be grown in situ or isolated. Thus, this study shows the different methods of isolation and in vitro systems employed for maintaining the structural integrity and development of preantral follicles.

Advances in isolation and culture systems of preantral follicles / AVANÇOS NO ISOLAMENTO E SISTEMAS DE CULTIVO DE FOLÍCULOS PRÉ-ANTRAIS

The preantral follicles enclosed in ovarian cortex represent about 95% of the entire follicular population and can be grown and matured in vitro in order to obtain mature and competent oocytes, which may be used in various reproductive biotechnologies applied to domestic animals. Studies related to folliculogenesis can be performed in vivo, by analyzing the expression of genes or proteins that are present in the ovary, and also in vitro with the use of different systems, in which the follicles can be grown in situ or isolated. Thus, this study shows the different methods of isolation and in vitro systems employed for maintaining the structural integrity and development of preantral follicles. Keywords: Biotechnology, development, folliculogenesis.

Os folículos pré-antrais presentes no córtex ovariano representam cerca de 95% de toda a população folicular e podem ser crescidos e maturados in vitro, visando a obtenção posterior de oócitos maturos e competentes, os quais poderão ser utilizados nas diversas biotécnicas da reprodução aplicadas aos animais domésticos. Os estudos relacionados com a foliculogênese podem ser feitos in vivo, através da análise de expressão de genes ou proteínas que estão presentes no ovário, e ainda in vitro com a utilização de diferentes sistemas, onde os folículos podem ser cultivados in situ ou isolados. Deste modo, neste trabalho foram abordados os diferentes métodos de isolamento e sistemas de cultivo in vitro empregados para a manutenção da integridade estrutural e desenvolvimento de folículos pré-antrais. Palavras-Chave: Biotécnicas, desenvolvimento, foliculogênese.