使用GnRHa破卵若LH <15代表反應不佳，應施打hCG1000iu提高取卵數量

Fertil Steril. 2016 Aug 1. pii: S0015-0282(16)62481-0. doi: 10.1016/j.fertnstert.2016.07.1068. [Epub ahead of print]

Dual trigger for final oocyte maturation improves the oocyte retrieval rate of suboptimal responders to gonadotropin-releasing hormone agonist.

Lu X1, Hong Q1, Sun L1, Chen Q1, Fu Y1, Ai A1, Lyu Q1, Kuang Y2.

Author information

Abstract

OBJECTIVE:

To identify the risk factors for suboptimal response to GnRH agonist (GnRH-a) trigger and evaluate the effect of hCG on the outcome of patients with suboptimal response to GnRH-a.

DESIGN:

A retrospective data analysis.

SETTING:

A tertiary-care academic medical center.

PATIENT(S):

A total of 8,092 women undergoing 8,970 IVF/intracytoplasmic sperm injection (ICSI) treatment cycles.

INTERVENTION(S):

All women underwent hMG + medroxyprogesterone acetate (MPA)/P treatment cycles during IVF/ICSI, which were triggered using a GnRH-a alone or in combination with hCG (1,000, 2,000, or 5,000 IU). Viable embryos were cryopreserved for later transfer.

MAIN OUTCOME MEASURE(S):

The rates of oocyte retrieval, mature oocytes, fertilization, and the number of oocytes retrieved, mature oocytes, and embryos frozen.

RESULT(S):

In total, 2.71% (243/8,970) of patients exhibited a suboptimal response to GnRH-a. The suboptimal responders (LH ≤15 mIU/mL) had a significantly lower oocyte retrieval rate (48.16% vs. 68.26%), fewer mature oocytes (4.10 vs. 8.29), and fewer frozen embryos (2.32 vs. 3.54) than the appropriate responders. Basal LH levels served as the single most valuable marker for differentiating suboptimal responders with the areas under the receiver operating curve of 0.805. Administering dual trigger (GnRH-a and hCG 1,000, 2,000, 5,000 IU) significantly increased oocyte retrieval rates (60.04% vs. 48.16%; 68.13% vs. 48.16%; and 65.76% vs. 48.16%, respectively) in patients with a suboptimal response.

CONCLUSION(S):

Basal LH level was useful predictor of the suboptimal response to GnRH-a trigger. Administrating dual trigger including 1,000 IU hCG for final oocyte maturation could improve the oocytes retrieval rate of GnRH-a suboptimal responder.

睪丸靜脈曲張併精蟲過少或無精症
施行靜脈曲張修復手術可提高精蟲過少一般取精或無精症TESE取精後施行ICSI後胚胎懷孕率活產率

Fertil Steril. 2016 Aug 12. pii: S0015-0282(16)62523-2. doi: 10.1016/j.fertnstert.2016.07.1093. [Epub ahead of print]

Undergoing varicocele repair before assisted reproduction improves pregnancy rate and live birth rate in azoospermic and oligospermic men with a varicocele: a systematic review and meta-analysis.

Kirby EW1, Wiener LE2, Rajanahally S3, Crowell K4, Coward RM5.

Author information

Abstract

OBJECTIVE:

To evaluate how varicocele repair (VR) impacts pregnancy (PRs) and live birth rates in infertile couples undergoing assisted reproduction wherein the male partner has oligospermia or azoospermia and a history of varicocele.

DESIGN:

Systematic review and meta-analysis.

SETTING:

Not applicable.

PATIENT(S):

Azoospermic and oligospermic males with varicoceles and in couples undergoing assisted reproductive technology (ART) with IUI, IVF, or testicular sperm extraction (TESE) with IVF and intracytoplasmic sperm injection (ICSI).

INTERVENTION(S):

Measurement of PRs, live birth, and sperm extraction rates.

MAIN OUTCOME MEASURE(S):

Odds ratios for the impact of VR on PRs, live birth, and sperm extraction rates for couples undergoing ART.

RESULT(S):

Seven articles involving a total of 1,241 patients were included. Meta-analysis showed that VR improved live birth rates for the oligospermic (odds ratio [OR] = 1.699) and combined oligospermic/azoospermic groups (OR = 1.761). Pregnancy rates were higher in the azoospermic group (OR = 2.336) and combined oligospermic/azoospermic groups (OR = 1.760). Live birth rates were higher for patients undergoing IUI after VR (OR = 8.360). Sperm retrieval rates were higher in persistently azoospermic men after VR (OR = 2.509).

CONCLUSION(S):

Oligospermic and azoospermic patients with clinical varicocele who undergo VR experience improved live birth rates and PRs with IVF or IVF/ICSI. For persistently azoospermic men after VR requiring TESE for IVF/ICSI, VR improves sperm retrieval rates. Therefore, VR should be considered to have substantial benefits for couples with a clinical varicocele even if oligospermia or azoospermia persists after repair and ART is required.

DNA甲基化對於基因調控具重要作用

玻璃化冷凍對會下降卵子或胚胎之DNA甲基化

http://www.ncbi.nlm.nih.gov/pubmed/?term=Liang+Y%2C+Fu+XW%2C+Li+JJ%2C+Yuan+DS%2C+Zhu+SE

Zygote. 2014 May;22(2):138-45. doi: 10.1017/S0967199412000512. Epub 2012 Oct 31.

DNA methylation pattern in mouse oocytes and their in vitro fertilized early embryos: effect of oocyte vitrification.

Abstract

This study was conducted to investigate the pattern of DNA methylation in vitrified-thawed mouse oocytes and their in vitro fertilized early embryos. Firstly, mouse oocytes at metaphase II (MII) stage of meiosis were allocated randomly into three groups: (1) untreated (control); (2) exposed to vitrification solution without being plunged into liquid nitrogen (toxicity); or (3) vitrified by open-pulled straw (OPS) method (vitrification). Oocytes from all three groups were fertilized subsequently in vitro. The level of DNA methylation in the MII oocytes and their early embryos was then examined by immunofluorescence using an anti-5-methylcytosine (anti-5-MeC) monoclonal antibody and fluorescein isothiocyanate (FITC)-conjugated goat anti-mouse IgG. Developmental rates to 2-cell embryos (62.28%) and blastocysts (43.68%) of the vitrified-thawed oocytes were lower (P < 0.01) than those of fresh oocytes (81.47%, 61.99%) and vitrification solution treated (79.20%, 60.04%) oocytes. DNA methylation (as reflected by 5-MeC fluorescence intensity) in the vitrification group was less (P < 0.01) for MII oocyte and 2- to 8-cell stages compared with that in the control and toxicity groups. Accordingly, a reduction in global genomic methylation due to vitrification of MII oocytes may result in compromised in vitro developmental potential in early mouse embryos.

添加2 M L-proline 於VS (15%DMSO+15%EG+0.5M sucrose+20% fetal bovine serum)
可提高卵子玻璃化冷凍解凍存活率88%>94%

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4944144/

Table 1

The development of ICSI oocytes after vitrification and thawing in mouse.

	Fresh group	Proline-free control	Proline group 1	Proline group 2
Survival rate %(n/n)	–	88.4 (557/630)a	94.7 (515/544)b	93.7 (518/553)b
ICSI rate %(n/n)	88.2 (157/178)a	79.0 (184/233)b	80.1 (173/216)b	81.8 (175/214)b
Two pronuclei rate (per oocyte) %(n/n)	94.9 (149/157)a	92.4 (170/184)a	93.6 (162/173)a	93.7 (164/175)a
Two-cell rate (per oocyte) %(n/n)	90.4 (142/157)a	76.1 (140/184)b	80.3 (139/173)b	79.4 (139/175)b
Blastocyst rate (per oocyte) %(n/n)	75.8 (72/95)a	51.4 (54/105)b	54.1 (53/98)b	52.4 (54/103)b
Implantation rate (per two-cell transferred) %(n/n)	80 (32/40)a	52.5 (21/40)b	57.5 (23/40)b	55 (22/40)b
Live birth rate (per two-cell transferred) %(n/n)	60.7 (34/56)a	38.3 (23/60)b	40 (24/60)b	38.6 (22/57)b
Healthy live birth rate %(n/n)	100 (34/34)a	100 (23/23)a	100 (24/24)a	100 (22/22)a
Birth weight (1 day old) (g)	1.70 ± 0.02a	1.77 ± 0.02a	1.74 ± 0.02a	1.76 ± 0.01a
Birth body length (1 day old) (cm)	2.85 ± 0.02a	2.91 ± 0.02a	2.85 ± 0.02a	2.90 ± 0.02a
Sex ratio (female/male)	19/15a	15/8a	9/15a	10/12a

Note: abValues with different superscripts in the same line are significantly different (P < 0.05). The data is shown as Means ± SE.

L-proline(2.00 mol/L)---新一代抗凍劑

可用於VS中，取代部分DMSO, EG
減少其對胚胎或卵毒性

(15% DMSO and 15% EG without L-proline)--->(7.5%DMSO+10%EG+2mg/L L-proline)
oocyte survival rate 89%--->93%

http://www.cmj.org/article.asp?issn=0366-6999;year=2016;volume=129;issue=16;spage=1963;epage=1968;aulast=Zhang

Chin Med J (Engl). 2016 20th Aug;129(16):1963-1968. doi: 10.4103/0366-6999.187846.

Cryobiological Characteristics of L-proline in Mammalian Oocyte Cryopreservation.

Zhang L1, Xue X2, Yan J1, Yan LY3, Jin XH1, Zhu XH1, He ZZ2, Liu J4, Li R3, Qiao J3.

Author information

Abstract

BACKGROUND:

L-proline is a natural, nontoxic cryoprotectant that helps cells and tissues to tolerate freezing in a variety of plants and animals. The use of L-proline in mammalian oocyte cryopreservation is rare. In this study, we explored the cryobiological characteristics of L-proline and evaluated its protective effect in mouse oocyte cryopreservation.

METHODS:

The freezing property of L-proline was detected by Raman spectroscopy and osmometer. Mature oocytes obtained from 8-week-old B6D2F1 mice were vitrified in a solution consisting various concentration of L-proline with a reduced proportion of dimethyl sulfoxide (DMSO) and ethylene glycol (EG), comparing with the control group (15% DMSO and 15% EG without L-proline). The survival rate, 5-methylcytosine (5-mC) expression, fertilization rate, two-cell rate, and blastocyst rate in vitro were assessed by immunofluorescence and in vitro fertilization. Data were analyzed by Chi-square test.

RESULTS:

L-proline can penetrate the oocyte membrane within 1 min. The osmotic pressure of 2.00 mol/L L-proline mixture is similar to that of the control group. The survival rate of the postthawed oocyte in 2.00 mol/L L-proline combining 7.5% DMSO and 10% EG is significantly higher than that of the control group. There is no difference of 5-mC expression between the L-proline combination groups and control. The fertilization rate, two-cell rate, and blastocyst rate in vitro from oocyte vitrified in 2.00 mol/L L-proline combining 7.5% DMSO and 10% EG solution are similar to that of control.

CONCLUSIONS:

It indicated that an appropriate concentration of L-proline can improve the cryopreservation efficiency of mouse oocytes with low concentrations of DMSO and EG, which may be applicable to human oocyte vitrification.

D1->D5    Pyruvate & glucose代謝量逐漸增加

D4->D5    O2消耗量逐漸增加

培養環境會影響胚胎之基因表現epigenome，進而影響胚胎之代謝及分化

Environmental and epigenetic effects upon preimplantation embryo metabolism and development

In vitro fertilization has provided a unique window into the metabolic processes that drive embryonic growth and development from a fertilized ovum to a competent blastocyst. Post-fertilization development is dependent upon a dramatic reshuffling of the parental genomes during meiosis, as well as epigenetic changes that provide a new and autonomous set of instructions to guide cellular differentiation both in the embryo and beyond. Although early literature focused simply on the substrates and culture conditions required for progress through embryonic development, more recent insights lead us to suggest that the surrounding environment can alter the epigenome, which can, in turn, impact upon embryonic metabolism and developmental competence.

IVM後22-24h可去除卵丘細胞加速未成熟卵M1進展至成熟卵M2

Theriogenology. 2016 May 30. pii: S0093-691X(16)30225-4. doi: 10.1016/j.theriogenology.2016.05.024. [Epub ahead of print]

Effect of removing cumulus cells from porcine cumulus-oocyte complexes derived from small and medium follicles during IVM on the apoptotic status and meiotic progression of the oocytes.

Ferré P1, Bui TM1, Wakai T1, Funahashi H2.

Author information

Abstract

The present study was undertaken to examine the apoptotic status and meiotic progression of oocytes from small follicle (SF; 0.5-2 mm in diameter) and medium follicle (MF; 3-6 mm in diameter) when the oocytes were denuded before, during, and after IVM. Cumulus-oocyte complexes (COCs) were collected from SF or MF of prepubertal gilt ovaries. Before or 20 hours after the start of IVM culture, some oocytes were denuded and cultured for IVM. At the end of IVM, apoptotic status and meiotic progression of the oocytes were compared with oocytes matured in the presence of cumulus cells (CCs) by Annexin-V/PI assay and 4',6-Diamidino-2-phenylindole staining. Apoptotic status of the oocytes was only affected by time when the oocytes were denuded. In both oocytes from SF and MF, although the incidence of early and late apoptotic oocytes was significantly higher when the CCs were removed before IVM, the rate was significantly lower when CCs were removed 20 and 44 hours after the start of IVM. The incidence of mature oocytes was significantly affected by both the origin of COCs and time when oocytes were denuded from the COCs. Although the percentage of mature oocytes was higher in MF than SF, maturation rates were significantly higher when oocytes were denuded 20 hours, as compared with 0 and 44 hours after the start of IVM. However, the percentage of mature oocytes with a morphologically normal spindle was significantly higher when oocytes were denuded 44 hours, rather than 22 hours of IVM. In conclusion, removing CCs 20 hours after the start of IVM seems to promote meiotic progression of the oocytes to the metaphase-II stage even when the COCs were collected from SF, although factor(s) from or communication with CCs during IVM may need to obtain a morphologically normal spindle in mature oocytes.

Copyright © 2016 Elsevier Inc. All rights reserved.

雷射打洞冷凍卵子中空透明帶ZP有助於冷凍精子施行IVF

PLoS One. 2014 Mar 11;9(3):e91892. doi: 10.1371/journal.pone.0091892. eCollection 2014.

Laser-assisted in vitro fertilization facilitates fertilization of vitrified-warmed C57BL/6 mouse oocytes with fresh and frozen-thawed spermatozoa, producing live pups.

Woods SE1, Qi P1, Rosalia E1, Chavarria T1, Discua A1, Mkandawire J1, Fox JG1, García A1.

Author information

Abstract

The utility of cryopreserved mouse gametes for reproduction of transgenic mice depends on development of assisted reproductive technologies, including vitrification of unfertilized mouse oocytes. Due to hardening of the zona pellucida, spermatozoa are often unable to penetrate vitrified-warmed (V-W) oocytes. Laser-assisted in vitro fertilization (LAIVF) facilitates fertilization by allowing easier penetration of spermatozoa through a perforation in the zona. We investigated the efficiency of V-W C57BL/6NTac oocytes drilled by the XYClone laser, compared to fresh oocytes. By using DAP213 for cryoprotection, 83% (1,470/1,762) of vitrified oocytes were recovered after warming and 78% were viable. Four groups were evaluated for two-cell embryo and live offspring efficiency: 1) LAIVF using V-W oocytes, 2) LAIVF using fresh oocytes, 3) conventional IVF using V-W oocytes and 4) conventional IVF using fresh oocytes. First, the groups were tested using fresh C57BL/6NTac spermatozoa (74% motile, 15 million/ml). LAIVF markedly improved the two-cell embryo efficiency using both V-W (76%, 229/298) and fresh oocytes (69%, 135/197), compared to conventional IVF (7%, 12/182; 6%, 14/235, respectively). Then, frozen-thawed C57BL/6NTac spermatozoa (35% motile, 15 million/ml) were used and LAIVF was again found to enhance fertilization efficiency, with two-cell embryo rates of 87% (298/343) using V-W oocytes (P<0.05, compared to fresh spermatozoa), and 73% (195/266) using fresh oocytes. Conventional IVF with frozen-thawed spermatozoa using V-W (6%, 10/168) and fresh (5%, 15/323) oocytes produced few two-cell embryos. Although live offspring efficiency following embryo transfer was greater with conventional IVF (35%, 18/51; LAIVF: 6%, 50/784), advantage was seen with LAIVF in live offspring obtained from total oocytes (5%, 50/1,010; conventional IVF: 2%, 18/908). Our results demonstrated that zona-drilled V-W mouse oocytes can be used for IVF procedures using both fresh and frozen-thawed spermatozoa, producing live pups. The ability to cryopreserve mouse gametes for LAIVF may facilitate management of large-scale transgenic mouse production facilities.

卵丘細胞與卵子能量ATP來源，脂質&葡萄糖代謝有關
卵丘細胞會吸收周遭葡萄糖提供卵子能量ATP來源

Theriogenology. 2016 Jun 7. pii: S0093-691X(16)30237-0. doi: 10.1016/j.theriogenology.2016.05.036. [Epub ahead of print]

Relationship between the number of cells surrounding oocytes and energy states of oocytes.

Munakata Y1, Ichinose T1, Ogawa K1, Itami N1, Tasaki H1, Shirasuna K1, Kuwayama T1, Iwata H2.

Author information

Abstract

Lipid content, ATP content, and histone acetylation are thought to reflect the energy state of cells. In addition, the energy state closely associates with growth and developmental ability of oocytes. Oocyte growth is accompanied by active proliferation of the surrounding granulosa cells (GCs), and GCs play a key role in the provision of energy substrates to the oocytes. In the present study, we first examined the relationship among the average number of GCs per follicle, the average number of cumulus cells (CCs) per oocyte, and the average lipid content in oocytes that developed in vivo within individual donor gilts. Second, we validated the relationship between the number of cells surrounding oocytes and the energy states of oocytes by using an IVC system of oocyte granulosa cell complexes (OGCs) derived from early antral follicles. We collected cumulus cells and oocyte complexes (COCs) from antral follicles (3-5 mm in diameter) and found that average lipid content in oocytes significantly correlated with the average number of both GCs/follicle and CCs/oocyte (P < 0.05). In the next series of experiments, we collected OGCs from early antral follicles (0.5-0.7 mm in diameter), and cultured them for 14 days, and then determined the cell number of OGCs, as well as the lipid content, ATP content, and acetylation level of H4K12 in oocytes grown in vitro. In addition, glucose consumption by OGCs was calculated from the sample media collected at Days 13 and 14. The lipid content of oocytes grown in vitro, significantly correlated with the number of cells surrounding the oocytes (P < 0.01) and with the level of glucose consumption by OGCs (P < 0.01). In addition, both ATP content and H4K12 acetylation levels of oocytes grown in vitro significantly correlated with the number of cells surrounding the oocytes (P < 0.05) and glucose consumption by OGCs (P < 0.05). In conclusion, the lipid content of oocytes depends on the number of cells surrounding the oocytes, and glucose uptake by OGCs is crucial for lipid content and ATP content, and H4K12 acetylation in oocytes.

2 step medium vs single medium
針對囊胚形成率，single medium略優於2 step medium

J Assist Reprod Genet. 2016 Aug 5. [Epub ahead of print]

Blastocyst culture using single versus sequential media in clinical IVF: a systematic review and meta-analysis of randomized controlled trials.

Sfontouris IA1,2, Martins WP3, Nastri CO3,4, Viana IG3,4, Navarro PA3, Raine-Fenning N1, van der Poel S5,6, Rienzi L7, Racowsky C8.

Author information

Abstract

PURPOSE:

The purpose of this study was to undertake a review of the available evidence comparing the use of a single medium versus sequential media for embryo culture to the blastocyst stage in clinical IVF.

METHODS:

We searched the Cochrane Central, PubMed, Scopus, ClinicalTrials.gov, Current Controlled Trials and WHO International Clinical Trials Registry Platform to identify randomized controlled trials comparing single versus sequential media for blastocyst culture and ongoing pregnancy rate. Included studies randomized either oocytes/zygotes or women. Eligible oocyte/zygote studies were analyzed to assess the risk difference (RD) and 95 % confidence intervals (CI) between the two media systems; eligible woman-based studies were analyzed to assess the risk ratio (RR) and 95 % CI for clinical pregnancy rate.

RESULTS:

No differences were observed between single and sequential media for either ongoing pregnancy per randomized woman (relative risk (RR) = 0.9, 95 % CI = 0.7 to 1.3, two studies including 246 women, I 2 = 0 %) or clinical pregnancy per randomized woman (RR = 1.0, 95 % CI = 0.7 to 1.4, one study including 100 women); or miscarriage per clinical pregnancy: RR = 1.3, 95 % CI = 0.4 to 4.3, two studies including 246 participants, I 2 = 0 %). Single media use was associated with an increase blastocyst formation per randomized oocyte/zygote (relative distribution (RD) = +0.06, 95 % CI = +0.01 to +0.12, ten studies including 7455 oocytes/zygotes, I 2 = 83 %) but not top/high blastocyst formation (RD = +0.05, 95 % CI = -0.01 to +0.11, five studies including 3879 oocytes/zygotes, I 2 = 93 %). The overall quality of the evidence was very low for all these four outcomes.

CONCLUSIONS:

Although using a single medium for extended culture has some practical advantages and blastocyst formation rates appear to be higher, there is insufficient evidence to recommend either sequential or single-step media as being superior for the culture of embryos to days 5/6. Future studies comparing these two media systems in well-designed trials should be performed.

使用GnRHa破卵可併用低劑量HCG1000 iu以提高取卵率&卵子成熟率

Fertil Steril. 2016 Aug 1. pii: S0015-0282(16)62481-0. doi: 10.1016/j.fertnstert.2016.07.1068. [Epub ahead of print]

Dual trigger for final oocyte maturation improves the oocyte retrieval rate of suboptimal responders to gonadotropin-releasing hormone agonist.

Lu X1, Hong Q1, Sun L1, Chen Q1, Fu Y1, AiAi1, Lyu Q1, Kuang Y2.

Author information

Abstract

OBJECTIVE:

To identify the risk factors for suboptimal response to GnRH agonist (GnRH-a) trigger and evaluate the effect of hCG on the outcome of patients with suboptimal response to GnRH-a.

DESIGN:

A retrospective data analysis.

SETTING:

A tertiary-care academic medical center.

PATIENT(S):

A total of 8,092 women undergoing 8,970 IVF/intracytoplasmic sperm injection (ICSI) treatment cycles.

INTERVENTION(S):

All women underwent hMG + medroxyprogesterone acetate (MPA)/P treatment cycles during IVF/ICSI, which were triggered using a GnRH-a alone or in combination with hCG (1,000, 2,000, or 5,000 IU). Viable embryos were cryopreserved for later transfer.

MAIN OUTCOME MEASURE(S):

The rates of oocyte retrieval, mature oocytes, fertilization, and the number of oocytes retrieved, mature oocytes, and embryos frozen.

RESULT(S):

In total, 2.71% (243/8,970) of patients exhibited a suboptimal response to GnRH-a. The suboptimal responders (LH ≤15 mIU/mL) had a significantly lower oocyte retrieval rate (48.16% vs. 68.26%), fewer mature oocytes (4.10 vs. 8.29), and fewer frozen embryos (2.32 vs. 3.54) than the appropriate responders. Basal LH levels served as the single most valuable marker for differentiating suboptimal responders with the areas under the receiver operating curve of 0.805. Administering dual trigger (GnRH-a and hCG 1,000, 2,000, 5,000 IU) significantly increased oocyte retrieval rates (60.04% vs. 48.16%; 68.13% vs. 48.16%; and 65.76% vs. 48.16%, respectively) in patients with a suboptimal response.

CONCLUSION(S):

Basal LH level was useful predictor of the suboptimal response to GnRH-a trigger. Administrating dual trigger including 1,000 IU hCG for final oocyte maturation could improve the oocytes retrieval rate of GnRH-a suboptimal responder.

冷凍解凍過程會下降M1 成熟為M2之比率
M2比M1更能在冷凍解凍過程後存活

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4917218/

鼠胚研究顯示
M1(未完全成熟)卵子可有效玻璃化冷凍
不管冷凍前IVM或冷凍後IVM均可達不錯囊胚率 (32% or 28%)
(新鮮M2 囊胚率 56%)

PLoS One. 2016 Jun 22;11(6):e0157785. doi: 10.1371/journal.pone.0157785. eCollection 2016.

Production of Live Offspring from Vitrified-Warmed Oocytes Collected at Metaphase I Stage.

Chang CC1, Chang WF2, Xu J3, Cheng AS4, Chang CC2, Nagy ZP1, Yang CC5, Ding ST2,6, Sung LY2,7,8.

Author information

Abstract

Vitrification of matured oocytes is widely adopted in human clinics and animal research laboratories. Cryopreservation of immature oocytes, particularly those at metaphase I (MI), remains a challenge. In the present work, mouse MI oocytes denuded of cumulus cells were vitrified and warmed (V/W) either prior to (V/W-BEFORE-IVM, n = 562) or after (V/W-AFTER-IVM, n = 664) in vitro maturation (IVM). Derivative metaphase II (MII) oocytes were then used for intracytoplasmic sperm injection (ICSI). In the control groups, in vivo matured MII oocytes were used freshly (FRESH-MII, n = 517) or after V/W (MII-V/W, n = 617). In vitro and in vivo developmental competencies were compared among groups. Satisfactory blastocyst rates were achieved in V/W-BEFORE-IVM (27.5%) and V/W-AFTER-IVM (32.4%) groups, albeit as expected still lower than those from fresh-MII (56.1%) or MII-V/W (45.6%) oocytes. Similarly, the term development rates from V/W-BEFORE-IVM and V/W-AFTER-IVM were 12.4% and 16.7% respectively, acceptable but lower than those of the fresh-MII (41.2%) and MII-V/W (23.3%) groups. These data demonstrate that oocytes collected at MI stage are amenable to V/W, which can be performed before or after IVM with acceptable development rates including production of healthy pups. These findings provide useful knowledge to researchers and clinical practitioners for preservation and use of the otherwise discarded MI oocytes.