Embryologist Tiny Dictionary for Mastering ICSI

Monash Biotech

May 27th, 2024

This in-depth glossary delves into the world of Intracytoplasmic Sperm Injection (ICSI), providing embryologists with a clear understanding of the essential terminology, procedures, and considerations involved in this advanced fertility technique.

👩‍🔬 Cell & Development 🤱

• Blastocyst:

  A mature embryo (typically 5–6 days post-fertilization) characterized by an inner cell mass (blastocyst inner cell mass, BICM) and a fluid-filled cavity (blastocyst cavity, BC). Blastocyst transfer is a common practice in ICSI cycles.

• Blastocyst Culture:

  Extending embryo development in vitro for several days beyond cleavage stages to reach the blastocyst stage, potentially improving implantation rates.

• Blastocyst Selection:

  Choosing the most viable blastocyst for transfer based on its morphology (appearance) and development stage using established grading systems.

• Cleavage Stage:

  The initial stages of cell division following fertilization, where the zygote undergoes rapid mitotic divisions to form a multicellular embryo (blastomere).

• Cryopreservation:

  The process of freezing and storing sperm, oocytes, or embryos at ultra-low temperatures for future use in assisted reproductive technologies (ART) cycles.

• Embryo:

  A fertilized egg that has undergone cell division and begun to develop into a multicellular organism.

• Gamete Intrafallopian Transfer (GIFT):

  A fertility treatment where oocytes and sperm are placed directly into a fallopian tube, allowing natural fertilization to occur. Not commonly used in conjunction with ICSI.

• Mature Metaphase II Oocyte (MII oocyte):

  An oocyte in its final stage of meiotic maturation, arrested at metaphase II and ready for fertilization.

• Oocyte (Egg):

  The female reproductive cell that fuses with a sperm to form a zygote.

• Oocyte Retrieval:

  The minimally invasive procedure of collecting oocytes from the ovaries, typically guided by transvaginal ultrasound.

• Sperm:

  The male reproductive cell that fertilizes the oocyte.

• Zona Pellucida (ZP):

  The transparent glycoprotein shell surrounding the oocyte, playing a crucial role in sperm-egg interaction and preventing polyspermy (fertilization by multiple sperm).

👩‍⚕️Conditions & Disorders 🧸

• Endometriosis:

  A condition where endometrial tissue grows outside the uterus, potentially impacting fertility by altering the endometrial environment.

• Hysterosalpingography (HSG):

  An X-ray examination to assess the patency and health of the fallopian tubes and uterus. May be performed before ICSI to evaluate potential implantation sites.

• Male Factor Infertility:

  A condition where sperm quality or quantity hinders natural conception. ICSI is often the recommended treatment option in such cases.

• Ovarian Hyperstimulation Syndrome (OHSS):

  A complication of ovarian stimulation medications used in IVF cycles, characterized by enlarged ovaries and fluid buildup in the abdomen.

• Pelvic Inflammatory Disease (PID):

  An infection of the female reproductive organs that can damage fallopian tubes and impact fertility.

• Varicocele:

  An enlargement of the veins in the scrotum, potentially affecting sperm quality.

🐣Fertility Procedures 🐤

• Assisted Hatching Technique:

  A procedure where the zona pellucida is thinned or weakened using lasers or chemicals to facilitate embryo implantation. May be considered for embryos with a thickened zona pellucida.

• Follicle Stimulating Hormone (FSH):

  A pituitary hormone that stimulates the development of follicles in the ovaries, often used in controlled ovarian stimulation (COS) protocols to promote multiple mature oocytes for ICSI.

• Intracytoplasmic Morphologically Selected Sperm Injection (ICSI-MSI):

  A specialized ICSI technique where high magnification and morphological analysis are used to select sperm with normal morphology for injection.

• Intracytoplasmic Round Spermatid Injection (ICSI-ROSI):

  An advanced technique using immature germ cells (round spermatids) retrieved from the testicles for ICSI in cases of severe male factor infertility.

• Intracytoplasmic Sperm Injection (ICSI):

  A form of IVF where a single healthy sperm is directly injected into the cytoplasm of the oocyte using micromanipulation techniques, bypassing the natural process of fertilization.

• In Vitro Fertilization (IVF):

  A broader term encompassing the process of fertilization occurring outside the body. Oocytes are retrieved, fertilized with sperm in a laboratory dish, and viable embryos are transferred back into the uterus.

• Luteinizing Hormone (LH):

  A pituitary hormone that triggers ovulation (oocyte release) from the ovary.

• Ovulation Induction:

  Medications or procedures used to stimulate ovulation in women who do not ovulate naturally. Often used in conjunction with ICSI cycles.

• Percutaneous Epididymal Sperm Aspiration (PESA):

  A surgical procedure to retrieve sperm directly from the epididymis, a coiled structure located above the testes, in cases of blockage preventing sperm from reaching the ejaculate.

• Testicular Sperm Aspiration (TESA):

  A surgical procedure to extract sperm directly from testicular tissue in cases of severe male factor infertility where sperm are absent from the ejaculate.

🔬Semen Analysis & Parameters 🐧

• Agglutination:

  Clumping of sperm cells, potentially hindering their motility and ability to reach the oocyte.

• Motility:

  The ability of sperm to move effectively, essential for reaching and fertilizing the oocyte. Various motility parameters are assessed during semen analysis.

• Oligospermia:

  Low sperm count, a potential indicator of male factor infertility.

• Oligozoospermia:

  Low sperm motility, impacting their ability to reach the oocyte.

• Sperm Washing:

  A technique used to separate sperm from seminal fluid and other cellular debris before ICSI to improve sperm quality and reduce the risk of introducing harmful substances into the oocyte.

🧬 Genetic Testing 👶

• Aneuploidy:

  An abnormal number of chromosomes in an embryo, potentially leading to pregnancy complications or miscarriage.

• Preimplantation Genetic Diagnosis (PGD):

  A diagnostic technique used to analyze embryos for specific genetic conditions before transfer, allowing selection of unaffected embryos for implantation.

• Preimplantation Genetic Screening (PGS):

  A screening technique used to assess the chromosomal makeup of embryos to identify those with a normal number of chromosomes (euploid), potentially increasing implantation and pregnancy rates.

🧫 ICSI Procedure🍼

• Acrosome Reaction:

  A crucial step where enzymes within the sperm head dissolve the zona pellucida, facilitating sperm-egg fusion. This process can be artificially induced during ICSI.

• Microinjection:

  The precise injection of a single sperm cell into the cytoplasm of the oocyte using specialized equipment like micromanipulators and injection needles.

• Micromanipulation:

  The use of specialized instruments under a microscope to handle oocytes, sperm, and embryos during ICSI procedures. This requires a high level of dexterity and technical expertise from the embryologist.

🛎️ ️Additional Considerations 🛎️

• Fertilization Rate:

  The percentage of oocytes injected with sperm that successfully undergo fertilization and begin cell division.

• Embryo Selection:

  Choosing the most viable embryos for transfer based on established criteria, including morphology, cleavage rate, and development stage.

• Embryo Culture:

  Maintaining embryos in a controlled laboratory environment to support their development until the transfer stage.

• Embryo Transfer:

  The process of transferring one or more selected embryos back into the woman’s uterus for potential implantation.

💉Evolving Landscape💉

• ICSI with Testicular Sperm Extraction (TESE-ICSI):

  A combined approach using TESE to retrieve sperm and ICSI for fertilization, offering hope for men with severe male factor infertility.

• ICSI with Artificial Activation Methods:

  Techniques to artificially induce the acrosome reaction in sperm when it fails to occur naturally, potentially improving fertilization rates.

Closing

ICSI is a complex and precise procedure demanding a high level of technical expertise and knowledge from embryologists. A thorough understanding of the scientific principles, underlying conditions, and technical procedures is crucial for successful ICSI outcomes.

This glossary provides a comprehensive foundation for embryologists to navigate the world of ICSI and contribute to achieving optimal results for patients seeking fertility treatment.