We all started off as embryos in our mothers' wombs. But, for the young ones of hundreds of sub-fertile couples taking the ART (Assisted Reproductive Technologies) route to parenthood, life begins in a petri dish, under the watchful eyes of an embryologist. The embryologist carefully handles the sperms and eggs from the time of collection, and thereafter either sets the stage for a swayamvara of sorts by mixing the sperms and eggs together — in vitro fertilisation (IVF), or facilitates an arranged match through intra cytoplasmic sperm injection (ICSI) or Intra cytoplasmic morphologically selected sperm injection (IMSI), and incubates them in the lab for fertilisation.
Says Sasikala Natrajamani, scientific director and chief embryologist, Crea Conceptions — Centre for Assisted Reproduction, Chennai: “Embryology looks at the very beginning of life from the one-celled organism — egg or sperm. Embryologists examine fertilisation and track the development of the embryo until it bears a resemblance to its progenitors.”
A long process
Putting the role of the embryologist into context, N. Pandiyan, chief consultant in Andrology and Reproductive Medicine and head of the department of Reproductive Medicine, Chettinad Hospital and Research Institute, Chennai, points out: “IVF is team work, and the success of the IVF programme depends on the infertility specialist who recruits the patient, plans proper stimulation protocol, does proper egg collection and effects appropriate placement of the embryos in the mother's womb. The embryologist who brings the egg and sperm together creates an embryo and assists in embryo transfer. The nursing staff provides the crucial support to the clinician and the embryologist. One cannot forget the pharmaceutical, labware and culture media companies that provide quality material. IVF is like an orchestra — the clinician infertility specialist normally conducts the orchestra, but he is ineffective without the accompanists.”
Says Rajvi Mehta, science director, Trivector Embryology Support Academy, Mumbai: “Embryologists are at the core and heart of all IVF procedures. They set up and maintain the culture laboratory, do the processing of the gametes (eggs and sperms), grow the embryos in the laboratory, and prepare them to be transferred into the uterus.”
Embryo selection
But, how do embryologists select viable embryos? And, what are the conditions necessary for successful implantation? Says Dr. Mehta: “We view the embryos under the microscope and select the ‘best' on the basis of their appearance and rate of development. Implantation is the ‘stage' that baffles the scientists the most. We manage to grow many embryos in the laboratory, but when we transfer these into the uterus not all implant. The failure of implantation may be due to the quality of the egg, sperm, embryo, external culture conditions, the uterine environment, and the hormones to sustain if the implantation occurs.”
Perfect timing
According to Sasikala Natrajamani: “Successful implantation requires the appropriately-timed arrival of a viable embryo into a receptive endometrium. The endometrium exhibits only a short period of receptivity known as the implantation window, and it is important to pinpoint the window of implantation, select the best embryo, and synchronise embryo transfer with the time of optimal endometrial receptivity. Poor embryo quality has also been identified as one of the major causes of implantation failure. However, good embryo quality does not always ensure 100 per cent implantation.”
About the advances in the field, Dr. Rajvi says: “we had ICSILimitations in ‘selecting' the right sperm are now overcome, thanks to new imaging techniques where we can magnify the sperm 6,200 times, enabling a clearer view.”
With awareness on genetic defects high, embryo screening is an important part of the embryologist's work. Says Dr. Natrajamani: “Embryologists have the expertise to identify risk factors for serious genetic conditions within the fertilised embryos, and select the most viable ones for implantation. In women with many miscarriages, couples who are carriers of genetic diseases or couples who have already had a child with a genetic disease, pre-implantation genetic diagnosis is done to distinguish genetically healthy embryos. Before embryo transfer, a single cell is removed from the embryo and studied in a special lab. This allows only genetically normal embryos to be transferred. With the advent of technology, even immature eggs are collected from the mother and matured, which saves the mother from taking as many drugs as she might have to, when mature eggs are collected. Clinical embryologists also work in emerging areas such as stem cell technology where embryonic stem cells are obtained from discarded or donated embryos.”
Saving it for later
Preservation of gametes and embryos for future use is yet another important part of the embryologist's work and is daunting, to say the least.
“Egg cryopreservation is particularly challenging because eggs have high water content, and the freezing process often leads to formation of ice crystals bursting the egg cells. The most common instance of egg cryopreservation have been for women undergoing chemotherapy and wishing to retain their reproductive options post treatment,” points out Dr. Natrajamani.
The very nature of their job requires embryologists to comply with high standards of ethics and quality control and regulations surrounding gamete and embryo handling, besides scrupulous maintenance of records.
After all no life, however young, can be handled lightly.
