scholarly journals Interval in the replacement of in vitro culture medium affects the integrity and development of equine preantral follicles

2018 ◽  
Vol 38 (12) ◽  
pp. 2284-2288
Author(s):  
Camila Bizarro-Silva ◽  
Suellen M. González ◽  
Isabela Búfalo ◽  
Andressa G. Lindquist ◽  
Fabiana D. Sarapião ◽  
...  
Keyword(s):  
In Vitro Culture ◽  
Culture System ◽  
Culture Medium ◽  
Follicular Development ◽  
Significance Level ◽  
Primordial Follicles ◽  
Preantral Follicles ◽  
Medium Exchange ◽  
Significant Difference

ABSTRACT: The efficiency of a culture system is related to the elaboration and replacement of a medium with conditions suitable for follicular development. Recent investigations suggested that in vitro culture medium should be replaced after specific time periods in various species. However, the suitable interval for the exchange of in vitro culture medium has not yet been established in equine species. The objective of this investigation was to evaluate the effect of medium exchange intervals of 24 hours (T24) or 48 hours (T48) for in vitro culture of preantral follicles at 2 or 6 days. At the end of the culture period, the fragments were processed using classical histology. Equine preantral follicles were classified according to morphological integrity and developmental stage. Data analysis was performed using Fisher’s test with a significance level of p<0.05. Out of a total of 399 follicles evaluated, 174 (43.6%) were primordial follicles, 225 (56.4%) were in development, and 63.76% were morphologically intact. In the in vitro culture performed over two days, there was no significant difference in relation to follicular integrity after medium replacement (p>0.05). Compared to the medium replacement at six days of culture, there was a statistically significant difference for T24 (68.9%, p<0.05). Therefore, we suggest changing the medium for equine species at 48 hours after the start of culture followed by subsequent daily replacements.

P–218 Analysis of the occurrence of microbial contamination in IVF culture system and the effect of microorganisms on embryo development and clinical outcomes

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
F Du ◽  
R Li ◽  
Q Zhang ◽  
W Wang
Keyword(s):  
Escherichia Coli ◽  
In Vitro Culture ◽  
Clinical Outcomes ◽  
Embryo Transfer ◽  
Follicular Fluid ◽  
Culture System ◽  
Microbial Contamination ◽  
Culture Medium ◽  
Ivf Et

Abstract Study question what is the source, prevalence, and influence of microbial contamination on in vitro fertilization (IVF) and embryo transfer (ET) cycles? Summary answer Microbial contamination mainly occurs on Day 2, most caused by Escherichia coli carried with semen. ICSI could prevent contamination effectively and get good clinical outcomes. What is known already Microbial contamination occurs in IVF-ET system occasionally, which is hard to stop happening. The IVF culture system and laboratory environment, the patients’ follicular fluid and semen are not absolutely sterile, while the antibiotics in culture medium isn’t effective for all microbe types, and the artificial operations may bring in microbes. Generally, microbial contamination leads to degradation of embryos, reduction the number of embryos available, and infection of female reproductive tract, which would increase the cost of patients’ time, money, and bring psychological damages. A better understanding of embryo contamination in IVF culture system is of added value. Study design, size, duration A total of 29583 IVF-ET cycles were enrolled in this prospective observational study, from January 2010 to December 2020, included 70 microbial contamination cycles discovered in Day1-Day3 (D1-D3) of in vitro culture. Follicular fluid and semen saved on oocyte retrieval day, and culture medium contaminated were examined and identified for microorganisms at each contamination cycle. Participants/materials, setting, methods Compared the contamination rate of different insemination methods (IVF/ICSI/IVF+ICSI), different in vitro culture days (D1-D3), and different samples examination (follicular fluid, semen, culture medium) respectively, identified the source of microorganism types, compared the IVF culture outcomes and clinical outcomes between total contamination group (TC group, 42 cases) and partial contamination group (PC group, 28 cases). Main results and the role of chance A total of 70 microbial contamination cases occurred in 29583 oocyte retrieving cycles (0.24%), and it was observed only in IVF embryos but never in ICSI (Intracytoplasmic sperm injection) embryos. 38 contamination cases occurred on D2 with a highest ratio (54.3%) compared to D1 (32.9%) and D3(12.9%); Compared with follicular fluid, semen was the main cause inducing contamination from D1 to D3, and Escherichia coli in semen and culture medium, Enterococcus faecalis in follicular fluid proved to be the most common sources. Compared with TC group, the PC group showed a lower rate of No-available embryos (21.4% vs 81.0%) and a higher rate of blastocyst formation (41.2% vs 28.6%), In addition, the clinical pregnancy rate of PC group was higher than that of TC group in both fresh and frozen-thawed embryo transfer cycles (31.3% vs 16.7%, 38.5% vs 0.0%). Limitations, reasons for caution Further study is still necessary to better understand the sources that induce microbial contamination embryos, and more efficient methods are required to remove the microbes on these contaminated embryos so as better develop and manage a sterile micro-environment for successful embryo growth. Wider implications of the findings: The differential embryonic microbe types associated to different IVF culture and clinical outcomes in patients undergoing IVF-ET might have profound implications for understanding the microbial sources and making a better management of IVF culture system. Trial registration number Not applicable

scholarly journals The Role of Androgens in Mammals Folliculogenesis

2018 ◽  
Vol 44 (1) ◽  
pp. 15
Author(s):  
Livia Brunetti Apolloni ◽  
Jamily Bezerra Bruno ◽  
Benner Geraldo Alves ◽  
José Ricardo de Figueiredo
Keyword(s):  
Androgen Receptor ◽  
In Vitro Culture ◽  
Steroid Hormones ◽  
Oocyte Maturation ◽  
Follicular Development ◽  
Follicular Growth ◽  
Preantral Follicles ◽  
Ovarian Cells

Introduction: Steroid hormones production is a physiological process termed steroidogenesis. An important stage of this process is the conversion of androgens into estrogens through aromatase enzyme. Furthermore, androgens are important in the process of folliculogenesis, promoting follicular growth in different species. Thus, the aim of this review was to present the process of synthesis, mechanism of action, and importance of androgens in folliculogenesis. Additionally, the main results of in vitro culture of ovarian cells in the presence of these hormones were emphasized.Review: Folliculogenesis begins in prenatal life in most of species and can be defined as the process of formation, follicular growth, and oocyte maturation. Preantral follicles represent 95% of the follicular population and assisted reproductive technologies have been developed (e.g., Manipulation of Oocytes Enclosed in Preantral Follicles - MOEPF) in order to avoid the great follicle loss that occurs naturally in vivo by atresia. The MOEPF aim to obtain a large number of competent oocytes from preantral follicles and then subject to in vitro maturation, fertilization, and culture for embryo production. However, the development of an efficient medium to ensure the follicular survival and oocyte maturation is the major challenge of this biotechnology. To achieve the success on in vitro culture, the effects of substances as androgens on follicular development have been evaluated. Androgens are steroid hormones produced in theca cells (TC) that are fundamental for follicular growth. These cells provide all the androgens required by the developing follicles for conversion into estrogens by the granulosa cells (GC). Androgens receptors (AR) are localized in cell cytoplasm of all follicular categories, being more expressed in preantral follicles. The androgen pathway initiates through its connection to its receptor, making a complex androgen-AR, that in the nucleus helps on the process of gene transcription related with follicular survival. This mechanism is androgen receptor genomic activity. In addition to genomic action, there is an androgen receptor non-genomic activity. This occurs through activation of AR and its interaction with different signaling molecules located on the cell membrane, triggering events that aid in the follicular development. Regardless of the androgens actions, ovarian cells of several species subjected to in vitro culture have shown the importance of these hormones on the follicle development. Recent studies demonstrated that androgens addition on the culture medium stimulated the activation of preantral follicles (bovine and caprine), antrum formation (swine), survival (non-primate), and oocyte maturation (antral follicles; bovine). Also, some studies suggest that the addition of these hormones on in vitro culture is dose-dependent and species-specific.Conclusion: This review shows the role of androgens in different stages of follicular development and its action as a substrate for steroidogenesis and transcription of genes related to follicular survival and oocyte maturation. However, when these hormones should be added during in vitro follicular culture and which concentration is required remains unclear, being necessary more studies to elucidate these aspects.

202 EFFECTS OF ASCORBIC ACID ON IN VITRO CULTURE OF CATTLE PREANTRAL FOLLICLES

2010 ◽  
Vol 22 (1) ◽  
pp. 259
Author(s):  
E. R. Andrade ◽  
R. van den Hurk ◽  
L. A. Lisboa ◽  
M. F. Hertel ◽  
F. A. Melo-Sterza ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
In Vitro Culture ◽  
Ovarian Tissue ◽  
Immunohistochemical Analysis ◽  
Development Stage ◽  
Nuclear Antigen ◽  
Primordial Follicles ◽  
Preantral Follicles ◽  
Ovarian Cortex

The mechanisms that regulate the gradual exit of ovarian follicles from the nongrowing, primordial pool are poorly understood. The objective of this study was to evaluate the effects of adding ascorbic acid to the media for in vitro culture of cattle ovarian fragments and to determine the effects of this addition on the growth activation and viability of preantral follicles. The ovarian cortex was divided into small fragments; 1 fragment was immediately fixed in Bouin’s solution (control). The other fragments were cultured for 2, 4, 6, or 8 days on culture plates in minimum essential medium (MEM) supplemented with insulin-transferrin-selenium (ITS), pyruvate, glutamine, hypoxantine, BSA, and antibiotics (MEM+) or in MEM+ plus ascorbic acid (5, 25, 50, 100, or 200 μg mL-1). Ovarian tissue was processed for classical histology, TEM, and immunohistochemical demonstration of proliferating cell nuclear antigen (PCNA). Preantral follicles were classified according to their development stage (primordial, intermediate, primary, and secondary) and on the basis of morphological features (normal or degenerated). Pair-wise comparisons were done using Tukey’s procedure. Chi-square test was used to compare percentages of follicles with PCNA-positive granulosa cells. All analyses were done with Statistical Analysis System (SAS Institute, Cary, NC, USA); P ≤ 0.05 was considered significant. Compared with control fragments, the percentage of primordial follicles was reduced (P ≤ 0.05) and the percentage of growing follicles was increased (P ≤ 0.05) in cultured cortical fragments, independent of the tested medium or incubation time. Furthermore, compared with control tissue, culture of ovarian cortex for 8 days reduced the percentages of healthy, viable follicles (P ≤0.05), but not when cultures were supplemented with 25, 50, and 100 μg mL-1 of ascorbic acid. Ultrastructural and immunohistochemical analysis of ovarian cortical fragments cultured for 8 days, however, showed the integrity and viability of follicles only when fragments were cultured in the presence of 50 μg mL-1 of ascorbic acid. In conclusion, this study demonstrated that addition of ascorbic acid to MEM at a concentration of 50 μg mL-1 not only stimulates the activation and subsequent growth of cattle primordial follicles that are cultured in vitro for 8 days but also safeguards the viability of these preantral follicles. E. R. Andrade and A. A. Alfieri are recipients of the PRODOC/CAPES fellowship.

160 COMPARATIVE STUDY OF IN VITRO CULTURE MEDIA AND ASSISTED HATCHING TECHNIQUES ON MOUSE EMBRYOS

2017 ◽  
Vol 29 (1) ◽  
pp. 188
Author(s):  
N. C. Negota ◽  
L. P. Nethenzheni ◽  
M. L. Mphaphathi ◽  
D. M. Barry ◽  
T. L. Nedambale
Keyword(s):  
In Vitro Culture ◽  
Chorionic Gonadotropin ◽  
Culture Medium ◽  
Culture Media ◽  
Assisted Hatching ◽  
Hatching Rate ◽  
Significant Difference ◽  
Equine Chorionic Gonadotropin ◽  
F1 Generation

The in vitro culture media and assisted hatching techniques remain challenging obstacles to be utilised widely. Mechanical, chemical, enzymatic thinning, and laser-assisted techniques have been used previously but information is still lacking on its application in livestock. The aim of this study was to compare the effect of 2 in vitro culture media (Hamster F10 and TMC-199) and 4 (mechanical, chemical, enzymatic, and laser) assisted hatching techniques on blastocyst formation and hatching rate using murine embryos as a model. The C57/b and Balb/c breeds were raised until they reached maturity and bred naturally to produce F1 generation. The light in the breeding house was controlled at 14 h light and 10 h dark. Feed and water were provided ad libitum for the mice. Superovulation of females were stimulated using equine chorionic gonadotropin and human chorionic gonadotropin. The F1 generation was used for the collection of the 400 blastocysts and randomly allocated into 4 assisted hatching techniques. Blastocysts were paired into a group of 10 and replicated 4 times for each assisted hatching technique. The general linear model of SAS version 9.4 (SAS Institute Inc., Cary, NC, USA) was used to analyse the data. Assisted hatching techniques of laser, mechanical, enzymatic, and chemical yielded 46.9 ± 37.1, 51.1 ± 40.2, 39.1 ± 35.8, and 33.3 ± 4.5%, respectively, under in vitro culture of Hamster F10. The TCM-199, laser, mechanical, enzymatic, and chemical assisted hatching techniques yielded 56.3 ± 43.3, 52.6 ± 35.5, 49.2 ± 37.5, and 33.9 ± 35.5%, respectively, with a significant difference. There was no significant difference observed in assisted hatching techniques and Hamster F10 culture medium. However, the hatching rate of embryos for all techniques was higher when in vitro cultured in TCM than cultured in Hamster F10. Hatching rate of blastocysts increased from chemical, enzymatic, mechanical, and laser with response to Hamster F10 and TCM; thus, laser is a suitable assisted hatching technique with TCM-199.

Effect of Pyruvate and Lactic Acid on the Development of Porcine Embryos

2011 ◽  
Vol 343-344 ◽  
pp. 611-617
Author(s):  
Bo Fu ◽  
Di Liu ◽  
Hong Ma ◽  
Zhong Qiu Li ◽  
Liang Wang ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Experimental Design ◽  
In Vitro Culture ◽  
Culture System ◽  
Culture Medium ◽  
Parthenogenetic Embryos

This study aimed to investigate the effects of pyruvate and lactic acid on the earlier development of porcine embryos. 5.56 mmol/L glucose in culture medium (NCSU-23) was replaced with 0.2 mmol/L pyruvate and 5.7 mmol/L lactic acid, namely mNCSU-23. Parthenogenetic embryos and nuclear transferred embryos were transferred into NCSU-23 or mNCSU-23 medium according to the experimental design. Parthenogenetic embryos and nuclear transferred embryos were evaluated for the numbers of 5-8 cells stage on Day 2. Blastocyst rates and the numbers of nuclei in the blastocyst were determined on Day 6. From the results, we observed a higher proportion of the embryos reaching 5-8 cells stage at 48h post-activation in mNCSU/NCSU treatment than control during the first part of in vitro culture(IVC) (P < 0.05). In addition, we also observed that the rates of blastocysts formation in mNCSU/NCSU treatments on Day 6 were significantly higher than other treatments, with mNCSU-23/mNCSU-23 treatment having the lowest rates of blastocysts formation on Day 6 (P < 0.05). Our results have demonstrated that replacing glucose with pyruvate and lactic acid during the first part of IVC may be beneficial to the development of the porcine embryos and stepwise culture system(mNCSU-23/NCSU-23) was optimal.

Effect of LH and Estradiol-17β Supplementation at Different Time Points on In vitro Development of Preantral Follicles in Sheep

2020 ◽  
Author(s):  
L.S.S. Varaprasad Reddy ◽  
B.R. Naik ◽  
A.V.N. Sivakumar ◽  
B. Punyakumari ◽  
J. Suresh
Keyword(s):  
In Vitro Maturation ◽  
Culture Medium ◽  
Follicular Development ◽  
Standard Medium ◽  
In Vitro Development ◽  
Preantral Follicles ◽  
Time Points ◽  
Vitro Development ◽  
Estradiol 17Β

Background: Ovarian follicular development and growth are controlled by many hormones and growth factors. Despite the fact that LH and estradiol-17β have been utilized for the in vitro culture of preantral follicles yet, the suitable time points of supplementation of LH and estradiol-17β is not known. Therefore this study aimed to investigate the influence of addition of LH and estradiol-17β at different time points on in vitro development of preantral follicles (PFs’) in sheep. Method: Preantral follicles isolated from the ovarian cortical slices using micro dissection method were cultured for six days in Bicarbonate buffered Tissue culture medium 199B (TCM 199B) or in a standard culture medium supplemented with LH (2 μg/ml) and estradiol-17β (5 ng/ml) at different points during the culture period. COCs isolated from the follicles at the end of six day culture in different treatments were subjected to in vitro maturation for additional 24h. Result: Supplementation of LH and estradiol-17β during last two days of the culture supported better proportion of PFs’ exhibiting growth whereas supplementation of LH and estradiol-17β during first two days of the culture supported better average increase in diameter and proportion of PFs’ exhibiting antrum formation at the end of six day culture. Further the oocytes in COCs isolated at the end of culture in these treatments and subsequently subjected to in vitro maturation (IVM) for 24hr developed at a higher frequency to MII (metaphase II) stage. Supplementation of LH and estradiol-17β to TCM 199B culture medium in early stages followed by standard medium alone in later stages supports better development of PFs’ in vitro. Following supplementation with LH and estradiol-17β for the first two days culture of PFs’ in standard medium appears to be advantageous for the development of preantral follicles in vitro.

Bovine dominant follicular fluid promotes the in vitro development of goat preantral follicles

2012 ◽  
Vol 24 (3) ◽  
pp. 490 ◽  
Author(s):  
A. B. G. Duarte ◽  
V. R. Araújo ◽  
R. N. Chaves ◽  
G. M. Silva ◽  
D. M. Magalhães-Padilha ◽  
...  
Keyword(s):  
Follicular Fluid ◽  
Culture Medium ◽  
Follicular Development ◽  
Ultrastructural Analysis ◽  
In Vitro Development ◽  
Preantral Follicles ◽  
Nuclear Membranes ◽  
Vitro Development ◽  
First Time

The aim of this study was to evaluate the effect of follicular fluid collected from bovine dominant follicles (bFF) on the in vitro development of goat preantral follicles and determine the best time to add this supplement to the culture medium. The preantral follicles were isolated and randomly distributed into four treatments in absence (control) or presence of 10% of bFF added on Days 0 (FF0–18), 6 (FF6–18) or 12 (FF12–18) of culture onwards. After 18 days, follicular development was assessed based on follicular survival, antral cavity formation, increased follicular diameter as well as fully grown oocyte (>110 μm) viability and meiosis resumption. The oocytes from the cultured follicles were in vitro-matured and processed for fluorescence or ultrastructural analysis. The results showed that on Day 18 the treatment FF0–18 had a significantly higher (P < 0.05) survival than control and FF12–18, but not FF6–18. The addition of bFF at the beginning of culture (FF0–18 and FF6–18) promoted a high percentage of follicular growth, meiosis resumption and early antrum formation. Moreover, this study described for the first time the ultrastructural analysis of caprine oocytes grown in vitro. This evaluation revealed that in the presence of bFF on (FF0–18) the in vitro-grown oocytes presented normal organelle distribution and well-defined, intact plasma and nuclear membranes. In conclusion, bFF originating from dominant follicles maintain the survival and promote the in vitro growth of goat preantral follicles when added at the beginning of culture.

scholarly journals Extract of Amburana cearensis maintains the survival of ovine preantral follicles during long-term ovarian tissue transport and promotes primordial follicle activation after in vitro culture

2018 ◽  
Vol 39 (5) ◽  
pp. 2001
Author(s):  
Vanúzia Gonçalves Menezes ◽  
Ricássio De Sousa Barberino ◽  
Bruna Bortoloni Gouveia ◽  
Rodrigo José de Souza Gonçalves ◽  
Jackson Roberto Guedes da Silva Almeida ◽  
...  
Keyword(s):  
In Vitro Culture ◽  
Culture Medium ◽  
Ovarian Tissue ◽  
Primordial Follicle ◽  
Chi Square ◽  
Preantral Follicles ◽  
Primordial Follicle Activation ◽  
Chi Square Test

This study evaluated the effect of Amburana cearensis extract as a preservation or culture medium for ovine ovarian tissue. Ovarian fragments were fixed in 4% buffered formaldehyde for 18 h (fresh control), stored in Minimal Essential Medium (MEM) or in A. cearensis extract (0.1; 0.2 or 0.4 mg/mL) at a temperature of 4ºC for 6, 12 or 24 h (preservation - experiment 1) or cultured for 7 days in ?-MEM+ or in A. cearensis extract without (0.1; 0.2 or 0.4 mg/mL) or with supplements (0.1+ ; 0.2+ or 0.4+ mg/ mL; experiment 2). The percentages of morphologically normal follicles and follicular activation were submitted to analysis of variance (ANOVA) and Tukey´s test. The values of TUNEL-positive cells were submitted to Chi-square test (P < 0.05). The storage of fragments for 6 h in MEM showed higher percentages of normal follicles (62%) and a lower rate of TUNEL positive cells (36.17%) compared to other treatments (normal follicles: 46%; 43% and 52%; TUNEL positive cells: 58.57%; 55.30% and 55.63% for Amb 0.1; Amb 0.2 and Amb 0.4 mg/mL, respectively). However, after 12 or 24 h, MEM (12 h: 48%; 24 h: 45%) and Amb 0.2 mg/mL (12 h: 37%; 24 h: 39%) showed similar percentages of normal follicles and TUNEL positive cells (MEM - 12 h: 43.26%; 24 h: 58%; Amb 0.2 mg/mL - 12 h: 50%; 24 h: 61%). After culture, ?-MEM+ recorded a higher percentage of normal follicles (58.25%) than A. cearensis treatments (32.8%; 25.4% and 34.2% for Amb 0.1; Amb 0.2 and Amb 0.4 mg/mL, and 22.25%; 20.0% and 36.6% for Amb 0.1+ ; Amb 0.2+ and Amb 0.4+ mg/mL, respectively) (P < 0.05). Follicular activation increased in all treatments (52.5%; 36.73%; 54.05%; 47.5% and 58.19% for ?-MEM+ ; Amb 0.1; Amb 0.1+ ; Amb 0.2+ and Amb 0.4+ mg/mL, respectively) compared to the fresh control (11.65%), except for Amb 0.2 mg/mL (23.69%) and Amb 0.4 mg/mL (28.85%) (P > 0.05). Moreover, after in vitro culture, A. cearensis at a concentration of 0.1 mg/mL maintained the percentage of TUNEL positive cells (30.0%) in a way that is similar to that observed in the fresh control (22%) (P > 0.05). In conclusion, ovine preantral follicles can be preserved at 4°C in MEM for 6 h. For longer periods of preservation (24 h), MEM and 0.2 mg/mL A. cearensis are recommended. Moreover, after in vitro culture, A. cearensis extract (0.1 mg/mL) showed higher activation and lower DNA fragmentation in ovine preantral follicles.

scholarly journals 2POSTHATCHING DEVELOPMENT SYSTEM: A NOVEL IN VITRO CULTURE OF BOVINE EMBRYOS

2004 ◽  
Vol 16 (2) ◽  
pp. 123 ◽  
Author(s):  
D.O. Brandão ◽  
G. Vajta ◽  
P. Maddox-Hyttel ◽  
D. Stringfellow ◽  
P. Lövendahl ◽  
...  
Keyword(s):  
In Vitro Culture ◽  
Bovine Serum ◽  
Culture System ◽  
Culture Medium ◽  
Inner Cell Mass ◽  
Fetal Bovine Serum ◽  
Cell Mass ◽  
Embryo Morphology ◽  
Fetal Bovine

Although high blastocyst rates can be achieved in somatic cell nuclear transfer, abortions and developmental abnormalities still hamper advancement. Reliable and practical methods to evaluate early embryonic development and differentiation are required to understand and overcome the problem. Our aim was to establish an in vitro culture system for monitoring posthatching development (PHD). Slaughterhouse-derived bovine oocytes were matured in vitro, fertilized (Day 0) and cultured (Holm et al., 1999, Theriogenology, 52, 683–700). On Day 8, degenerated embryos were removed from each well and 400L of modified culture medium (SOFaaci plus 0.5% glucose and 10% fetal bovine serum) were added. At Day 11, hatched blastocysts were selected by scoring them as Quality 1 (Q1: &gt;1.0mm, clear trophoblast, compact inner cell mass), Quality 2 (Q2: 0.5mm, dark spots in the trophoblast, less compact inner cell mass), or Quality 3 (Q3: &lt;0.5mm, many dark spots in the trophoblast, spread inner cell mass). The resulting 304 blastocysts in 12 replicates were then loaded into 15mm×1.2 gel tunnels of 2.4% agarose in PBS, supplemented with either 5% (Agar5) or 10% (Agar10) fetal bovine serum, covered with the modified culture medium, and then incubated at 38.5°C in 5% CO2, 5% O2, 90% N2. Embryo morphology and length were evaluated using a stereomicroscope on Days 12, 13, 14 and 15. On Day 14, 75 embryos were removed, biopsed (1mm) for sex determination of each embryo, and processed for light and transmission electron microscopy. Qualitative and quantitative data were analyzed by χ2 test and GLM procedure of SAS, respectively, with P level of 0.05. A total of 170 embryos (56% of total) initiated elongation. This percentage was higher (LSmeansSD, n=12; P&lt;0.05) in Agar10 v. Agar5 in both Q1 (889 v. 637), Q2 (667 v. 485) and Q3 embryos (529 v. 278). Mean embryo length (mm; LSmeansSEM) on Day 13 was higher (P&lt;0.05) in Q1 (2.10.2, n=49) and Q2 (1.71.4, n=98) than Q3 (1.20.3, n=23). On Day 14, Q1 embryos (3.50.2) were longer (P&lt;0.01) than Q2 and Q3 embryos (2.70.1 and 2.00.3). On Day 15, Q1, Q2 and Q3 embryos (4.40.5, n=24, 4.00.3, n=45 and 2.90.6, n=14, respectively) had similar length, probably influenced by the low number of Q3 embryos. The percentage of males was higher (P&lt;0.001) in Q1 (95%; n=40), but similar in Q2 (39%; n=26) and Q3 (71%; n=7). Light microscopy confirmed hypoblast and epiblast formation. Ultrastructural analysis revealed that the latter had penetrated the trophoblast (Rauber’s layer), forming an embryonic disc including many degenerative cells. In conclusion, this culture system represents the first model for rapid growth, elongation, and initial differentiation of bovine posthatching embryos.

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