The Eggs That Poke!

Eggschain Team 0

The objective of writing this article is to illustrate one of the many interesting aspects of egg-freezing and/or In-Vitro Fertilization (IVF). In this article, we will focus on the unusual sensations certain women might feel during the last 36 hours prior to the extraction, or retrieval, of eggs from the ovaries. This procedure is performed for the purpose of either freezing the collected eggs, which can allow patients to better control the timing of pregnancies, or proceed with IVF to obtain developing embryos.

36 hours prior to the extraction of the eggs, the patient’s physician or coordinating nurse will ask the patient to inject a “trigger shot”. The purpose of this trigger shot is to induce the eggs to undergo final maturation process, in preparation for extraction, or in the natural course of reproduction for ovulation.  Prior to this, eggs have been growing within their follicles and storing the necessary biomolecules to be used during early embryonic growth. After attaining the prerequisite follicle size, as denoted by ultrasound determination, the egg maintains a large nucleus (i.e. the ‘command center’ of the cell and houses DNA) which can be visualized under a microscope, but is not yet ready for fertilization by a sperm.

In order for the egg to mature and become chromosomally competent for fertilization (this process is called maturation), a shot of HCG (human chorionic gonadotrophin) is administered in order for the eggs to become chromosomally ready, so that it can receive sperm shortly after. During the process of maturation, the below occurs:

  • Structure protein is changed.
  • The structure of the nucleus breaks down.
  • The chromosome in the eggs undergo a structure change.
  • Membranes of the cell completely change.

Receiving the sperm can potentially occur naturally through intercourse or can potentially occur years later, post freezing in a liquid nitrogen tank, and post thawing/unfreezing when the patient is ready to conceive a baby herself or through a surrogate.

This maturation process, said in a more scientific manner, is the below:

“In order for the egg to mature and become chromosomally competent for fertilization (haploid), a shot of HCG (human chorionic gonadotrophin) is administered in order to induce germinal vesicle break down (GVBD) and the final round of maturation which produces a polarbody containing meiotically dividing chromosomes as well as cytoplasmic enzymatic activity and membrane modifications which isolates the egg from other follicular cells and thus create the egg-cumulus complex.”

The above is a lot to accomplish within 36 hours and it’s not surprising therefore that all this cellular activity may elicit sensations which may come to the attention of the individual undergoing this procedure. In this phase, larger and still growing follicles can potentially press on the nerve endings on the ovaries.

These sensations occurring during the 36 hours following the trigger shot may include the individual feeling that their eggs (still within ovarian follicles) are flipping, twitching, rotating, dancing, or even poking”! It is almost as though the eggs are getting ready to come out of the follicles. Of course, some may not feel anything at all.

All of the above sensations may indicate that eggs or entire follicles are very active during this maturation phase. The poking sensation is accompanied by slight pain on the level of 1-1.5 out of 10, on the scale of 0-10. 0 being no pain at all, and 10 being the most severe pain one has experienced in their lives. In this case, the sensation is noticeable, but it is not unduly painful.

We do not want to attribute these unusual sensations to any particular phase of the maturing process but to document that they may occur and be noticeable to a given individual. It is worth repeating that some women may not feel any sensation at all and their eggs could still potentially mature for extraction after the period of 36 hours.

It is also worth noting that eggs are single cell entities. Therefore, just like any other cells elsewhere in the human body, it performs very limited function on their own. So, an egg is not a complex being that can perform complex functions on its own, but is simply a component that contributes to process of reproduction.

The editors will write more about different aspects of egg freezing and IVF as well as related topics in the future.


This does not constitute medical advice. Please consult your doctor for your specific situation. Lifestyle choices are individuals’ choices.

It is written by Eggschain editors, scientifically reviewed by Dr. Kenneth Drury, PhD, HCLD, who holds a Post-Doc in Molecular Function of Maturation Promoting Factor from University of California Berkeley, and medically reviewed by Hugh Taylor, MD, the Anita O’Keeffe Young Professor and Chair, Department of Obstetrics Gynecology and Reproductive Sciences at Yale School of Medicine and Chief of Obstetrics and Gynecology at Yale-New Haven Hospital. He is also Professor of Molecular, Cellular and Developmental biology at Yale University.

Categories: Uncategorized