Embryology Lab

Embryology Lab

The Lab is the key for success!

The lab is a critical part of any IVF process. What sets us apart from other fertility centers is the quality of our labs and our esteemed clinical and research teams. We had one of the best teams in the world build our IVF labs with the best standards for air environment, technologies, and equipments. Our labs, in NYC and CT, are state-of-the-art facilities with every aspect designed to maximize your chances of having a healthy baby. Our expertise and dedication to lab operations continuously produces high pregnancy rates.

Egg Assessment

Following the egg retrieval, our embryologists will look at the eggs and grade them as:



Immature: We usually monitor it for 24 hours to see if it matures in the lab

Mature: Only mature eggs undergo fertilization by IntraCytoplasmic Sperm Injection (ICSI) because immature eggs do not fertilize with sperm and thus cannot produce a healthy embryo


Not good or degenerate


Good mature eggs usually make embryos. Embryo grading is the most commonly used method to assess embryos for potential transfer inside the uterus. During the IVF cycle, embryos are cultured in the lab and are evaluated on an almost daily basis until the day of the embryo transfer. The better the embryos look under the microscope (better grading), the better the chances of having a pregnancy.

The typical development of human embryos is the following:

  • Day 0: This is the day of egg retrieval. Mature eggs will be inseminated with the sperm with or without ICSI. The embryos are usually checked for fertilization but not graded.
  • Day 1: Fertilization assessment. Our Lab will send you an email with how many eggs get fertilized or pending fertilization.
  • Day 2: Embryo is usually 2-4 cells.
  • Day 3: Embryo is usually 6-10 cells and usually is graded on this day! Depending on your treatment plan, our Lab might contact you on this day with an update.
  • Day 4: Embryo is usually 16-32 cells.
  • Day 5-7: Embryo is usually a Blastocyst and usually is graded on this day! This is the developmental stage that occurs prior to implantation inside the uterus. This is the stage when PGT (Preimplantation Genetic Testing) can be done and then they get frozen for possible future use. Depending on your treatment plan, our Lab might contact you on this day with an update.


Zaher Merhi and Marco Mouanness. Intraovarian platelet-rich plasma administration could improve blastocyst euploidy rates in women undergoing in vitro fertilization. Clin Exp Reprod Med. 2022;49:210-214.

Zaher Merhi et al. Embryo quality but not pronuclear score is associated with clinical pregnancy following IVF. J Assist Reprod Genet. 2014;31:279-83. 

Zaher Merhi et al. Male adiposity impairs clinical pregnancy rate by in vitro fertilization without affecting day 3 embryo quality. Obesity. 2013;21:1608-12.

Zaher Merhi et al. Reproductive potential of mature oocytes after conventional ovarian hyperstimulation for in vitro fertilization. Int J Gynaecol Obstet. 2016;133:230-3

Zaher Merhi et al. Gender “tailored” conceptions: should the option of embryo gender selection be available to infertile couples undergoing assisted reproductive technology? J Med Ethics. 2008;34:590-3.