In order to perform an assisted reproduction procedure, it is necessary to retrieve the gametes (eggs and sperm cells) from the ovaries and testicles respectively. The eggs are retrieved from the ovaries during a procedure called follicular aspiration.
Sperm cells are retrieved from the semen usually obtained by masturbation; however, they can also be directly retrieved from the testes, by means of a direct or surgically-guided puncture.
The eggs (female gametes) are born with the woman’s ovaries. No new eggs are produced throughout life. In her first menstruation, a woman has, approximately, 400,000 eggs in her ovaries. Each egg is contained within a microscopic cell structure called follicle. When the woman begins her reproductive life with her first menstruation, a complex system of hormonal signals is set in motion from the Hypothalamus and the Pituitary glands, situated at the base of the brain, which sends signals to the ovary. Consequently, the ovary starts a process of maturation of several follicles in each menstrual cycle. However, in general, only one of them completes its maturation and releases the egg in a process known as ovulation. The remaining follicles that accompanied the dominant one, which was ovulated, are reabsorbed, and the same occurs with the eggs contained inside. Therefore, in each menstrual cycle a follicle matures with its egg and at least 5 to 10 additional follicles are lost (reabsorbed) including their eggs.
The developing follicle can be seen by ultrasound as a small sac with fluid inside, observable when its size is approximately 3 mm. Once maturation is complete (around days 12 to 14 of the menstrual cycle), the size of the follicle can reach 2 centimeters, and is easily identified by vaginal ultrasound.
The first aim when the woman is preparing for in vitro fertilization is to hormonally stimulate the ovaries, so that several follicles can complete their maturation together with the dominant follicle, and therefore retrieve several mature eggs. This is achieved with injections that resemble the hormones with which the Pituitary naturally stimulates the ovaries. In this way, as the hormonal stimulus on the ovaries increases, several follicles mature, instead of only one.
Both ultrasound observation of the ovaries and hormonal markers make it possible to identify when follicles are ready to retrieve mature eggs. When this happens, “follicular aspiration” is programmed.
A follicular aspiration consists of the retrieval of eggs from the ovaries, by means of ultrasound guided follicular punction and fluid aspiration (VIDEO). The eggs thus obtained are kept in culture media, in incubators waiting for an In Vitro Fertilization (IVF), or an Intracytoplasmic Sperm Injection (ICSI), or to be frozen for future use.
Sperm production is a continuum (unlike the egg, which is produced only once a month). Therefore, sperm cells can be obtained at any time. Usually, sperm cells are recovered from semen which is generated by masturbation on the same day of egg retrieval. Once semen is obtained, sperm cells are extracted from the semen by means of laboratory techniques and suspended in culture media, which resembles the fluid of the Fallopian tube, where fertilization naturally takes place.
In special conditions, sperm cells can be directly retrieved from the testes (where they are produced), or from a duct, called epididymis. Both procedures are invasive and require either a direct puncture or a small surgery, where the sperm-producing ducts are visualized, and the sperm cells are retrieved from them. In this case, the sperm cells must be injected into the egg (ICSI is always required, as it will be seen later).
The Latin American Registry of Assisted Reproduction (RLA) thanks the 204 institutions accredited by REDLARA which, every year, report their data to RLA.
This voluntary and rigorous contribution makes it possible to generate a powerful database, which helps doctors and patients take decisions based on the best existing regional evidence.
This educational portal is the result of a collaborative activity between the Latin American Network of Assisted Reproduction (REDLARA), and University Diego Portales from Chile, which allow the link between the reproductive science and technology advances with the needs of people suffering from infertility and other forms of reproductive impairments.
We thank Dr. Ariel Ahumanda and Dr. Gustavo Martínez from Argentina for: images and videos of spontaneous in vitro fertilization, ICSI and PGT,
Dr. Roger Molinas from Paraguay for: videos of follicular aspiration and embryo transfer,
Dr. Javier Crosby from Chile for: images of different stages of in vitro embryo development,
Dr. Yasuyuki Mio from Japan for his video of in vitro embryo development.
We especially thank the industry for providing the financial support, which is so necessary to keep the Latin American registry as a pillar of this international cooperation, which today includes 16 countries and more than 200 collaborative institutions, from Mexico in the north to Chile in the far south.
