The ability to predict the likelihood of a live birth after single fresh embryo transfer is important for treatment planning and managing patient expectation, particularly in their first in vitro fertilization (IVF) cycle. Cryopreservation of supernumerary embryos is often regarded as an important prognostic variable and a surrogate marker of success for several reasons. While previous large studies have examined the association between the number of oocytes retrieved and cleavage-stage embryos available, and the odds of a live birth following a fresh embryo transfer, the relationship between the number of supernumerary blastocysts cryopreserved following a fresh embryo transfer has not been rigorously studied. We performed a retrospective analysis of data collected between 2006 and 2018 for all first time IVF patients with a fresh autologous day 5 single blastocyst transfer. The relationship between the likelihood of a live birth and number of supernumerary blastocysts cryopreserved was assessed according to patient age group. In patients aged <35 years and 35-39 years old, the likelihood of a live birth increased linearly from 0.33 (95%CI:0.31–0.34) to 0.80 (95%CI:0.74–0.86; P<.0001) and 0.30 (95%CI:0.28–0.32) to 0.82 (95%CI:0.73–0.91;P<.0001) between 1-6 blastocysts cryopreserved and then non-linearly to 0.95 (95% CI 0.92–0.97; P<.0001) and 0.96 (95%CI:0.93–0.99; P<.0001) if 10 or more blastocysts were cryopreserved, respectively. When aged 40 years and above, the likelihood of a live birth increased linearly from 0.26 (95%CI:0.19–0.32) to 0.83 (95%CI:0.68–0.97; P<.0001) between 1-4 blastocysts cryopreserved and then non-linearly to 0.99 (95%CI:0.98–0.99; P<.0001) if 10 or more blastocysts were cryopreserved. The present study demonstrated a non-linear relationship between the number of supernumerary blastocysts cryopreserved and the likelihood of a live birth after single blastocyst transfer in the first autologous fresh IVF/ICSI cycle across different age groups.

Hormones must be balanced and dynamically controlled for the Female Reproductive Tract (FRT) to function correctly during the menstrual cycle, pregnancy, and delivery. Gamete selection and successful transfer to the uterus, where it implants and pregnancy occurs, is supported by the mucosal epithelial lining of the FRT ovaries, uterus, cervix, fallopian tubes, and vagina. Successful implantation and placentation in humans and other animals rely on complex interactions between the embryo and a receptive female reproductive system. The FRT's recent breakthroughs in three-dimensional (3D) organoid systems now provide critical experimental models that match the organ's physiological, functional, and anatomical characteristics in vitro. This article summarizes the current state of the art on organoids generated from various parts of the FRT. The current analysis examines recent developments in the creation of organoid models of reproductive organs, as well as their future directions.

Is there any possible synergic effect of fertility outcome between spindle view-assisted intracyto-plasmic sperm injection (SV-ICSI) with or without assisted oocyte activation (AOA) for patients with low fertilization rate history? To explore the answer, a retrospective study was held in our fertility center by reviewing patients receiving SV-ICSI during 2019/03 to 2023/06. Total 47 pa-tients were included, the fertility outcomes of intervention group (AOA-SV-ICSI, 14 patients) and control group (SV-ICSI, 33 patients), such as fertilization rate, blastocyst formation rate and clin-ical pregnancy rate, were analyzed. The blastocyst formation rate between groups was signifi-cantly higher in AOA-SV-ICSI group (p=0.020), but the fertilization rate and clinical pregnancy rate did not reach any statistical significance. This discovery of increased blastocyst formation rate in low fertilization rate patients could possibly help them in getting more usable embryos in fertility treatment.

Trophoblasts are the first cell-type to be specified during embryogenesis, and they are essential for placental morphogenesis and function. Trophoblast stem (TS) cells are the progenitor cells for all trophoblast lineages; control of TS cell differentiation into distinct trophoblast subtypes is not well understood. Mice lacking the transcription factor OVO-like 2 (OVOL2) fail to produce a functioning placenta, and die around embryonic day 10.5, suggesting that OVOL2 may be critical for trophoblast development. Therefore, our objective was to determine the role of OVOL2 in mouse TS cell fate. We found that OVOL2 was highly expressed in mouse placenta and differentiating TS cells. Placentas and TS cells lacking OVOL2 showed poor trophoblast differentiation potential, including increased expression of stem-state associated genes (Eomes, Esrrb, Id2) and decreased levels of differentiation-associated transcripts (Gcm1, Tpbpa, Prl3b1, Syna). Ectopic OVOL2 expression in TS cells elicited precocious differentiation. OVOL2 bound proximate to the gene encoding inhibitor of differentiation 2 (ID2), a dominant negative helix-loop-helix protein, and directly repressed its activity. Overexpression of ID2 was sufficient to reinforce the TS cell stem state. Our findings reveal a critical role of OVOL2 as a regulator of TS cell differentiation and placental development, in-part by coordinating repression of ID2.