INSIDE EMBRYO · LEARN AT YOUR OWN PACE
Inside the
IVF laboratory.
Follow the careful work between egg collection and embryo storage. Open each picture to understand what happens, why it matters and what you can ask.
Explore the pathway ↓
FOLLOW THE PICTURES. OPEN THE EXPLANATION.
Where are you in the laboratory journey?
Select any stage to see a short explanation and a question to ask your team.
Jump to a stage
Your pathway, one step at a time.
Follow a common pathway from oocyte retrieval to embryo vitrification. Day 0 is egg collection. Identity checks, witnessing and traceability continue throughout. Egg and sperm preparation can run in parallel. This is patient education, not a laboratory protocol.
DAY 0 · CLINIC TO LABOocyte retrieval (OPU)Explore this stage
The clinical team collects follicular fluid and passes it to the laboratory for egg identification.
Follicle count and egg count are not the same.
Egg and sperm preparation
DAY 0 · OOCYTE PREPARATIONFinding, washing & holding the eggsExplore this stage
The embryologist searches the fluid for cumulus–oocyte complexes, washes them and places them into suitable culture conditions.
Cumulus cells surround the oocyte at collection.
DAY 0 · ALONGSIDE EGG PREPARATIONSperm preparationExplore this stage
The sample is assessed and prepared to obtain sperm for the chosen fertilisation method.
Preparation is adapted to the sample and treatment plan.
These preparations may take place alongside one another.
The selected fertilisation route
ONE FERTILISATION ROUTEConventional IVFExplore this stage
Prepared sperm and eggs are placed together in culture so fertilisation can occur.
This is an alternative to ICSI; the same egg does not routinely undergo both.
ICSI ROUTE · BEFORE INJECTIONDenudation & maturity assessmentExplore this stage
Surrounding cumulus cells are removed so the oocyte can be assessed for maturity before ICSI.
Mature MII oocytes are selected for injection. Not every retrieved egg is mature.
ICSI ROUTE · DAY 0Intracytoplasmic sperm injectionExplore this stage
An embryologist injects a single sperm into a mature oocyte using micromanipulation equipment.
Injection does not guarantee fertilisation.
IVF and ICSI are alternatives. Both routes return to controlled culture.
AFTER IVF OR ICSIControlled incubationExplore this stage
Eggs are returned to controlled culture conditions while the laboratory maintains the environment.
Observation schedules and incubator systems vary between laboratories.
DAY 1 · USUALLY THE NEXT MORNINGFertilisation assessmentExplore this stage
The laboratory checks for signs of fertilisation, including pronuclei. Two pronuclei are a usual observation of normal fertilisation.
This observation is not a chromosome test or a promise of continued development.
USUALLY DAYS 2–3Cleavage-stage cultureExplore this stage
The embryo divides into smaller cells. The team considers cell number, appearance and timing.
Some plans include transfer or freezing at this stage rather than extended culture.
OFTEN AROUND DAY 4Compaction & morulaExplore this stage
Cells become closely packed as the embryo develops towards a morula.
Embryos may progress at different rates or stop developing.
COMMONLY DAYS 5–6 · SOMETIMES LATERBlastocyst assessment & selectionExplore this stage
The team assesses blastocyst expansion, inner cell mass and trophectoderm, alongside developmental timing.
If genetic testing is planned, biopsy is a separate, consented step. It is not routine for everyone.
FOR SUITABLE EMBRYOS · WHEN PLANNEDVitrification & cryostorageExplore this stage
Embryos undergo cryoprotectant exposure and rapid cooling, then remain in identified cryostorage.
Storage does not guarantee survival after warming or a future pregnancy. Follow-up consent and records matter.
The number of eggs collected, eggs fertilised and embryos suitable for use may differ. Your team explains your own results and the next agreed step.
CONTINUE YOUR READING
The latest in IVF Laboratory.
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A LITTLE CLARITY GOES A LONG WAY
You may have heard…
Let’s look at the facts.
Five common misunderstandings about ivf laboratory. Swipe through each one.
01 / IVF Laboratory
An embryo incubator is only a warm cupboard.
Incubation involves controlled conditions, including temperature and gases. Culture media and careful handling also help maintain a suitable environment.
Read supporting guidance →02 / IVF Laboratory
A standard embryo photograph shows its chromosomes.
Appearance under the microscope does not reveal a chromosome count. PGT-A is a separate test of sampled cells, with limitations that need discussion.
Read supporting guidance →03 / IVF Laboratory
Time-lapse imaging guarantees a higher chance of a baby.
Time-lapse records development. Current HFEA guidance does not find improved chances of a baby for most patients from its use as an add-on.
Read supporting guidance →04 / IVF Laboratory
Every egg collected will fertilise.
Collection and fertilisation are separate milestones. Not every collected egg is suitable or will fertilise; the laboratory reports what it observes.
Read supporting guidance →05 / IVF Laboratory
A frozen embryo keeps growing while it is stored.
Cryostorage preserves embryos at very low temperatures; they do not continue developing in storage. The laboratory warms and assesses them when they are needed.
Read supporting guidance →1 of 5
EXPLORE MORE IN THIS CATEGORY
Keep learning about IVF Laboratory.
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CONNECT THE IDEAS
Where would you like to go next?
Embryo Development
Look more closely at the stages described in a laboratory update.
Explore Embryo Development →IVF Journey
Connect laboratory work with appointments, treatment and follow-up.
Explore IVF Journey →Embryology
Build your understanding of reproductive cells and early development.
Explore Embryology →FOR YOUR NEXT CONVERSATION
Leave with a question.
Come back with more clarity.
UNDERSTANDWhich laboratory result are we discussing?
ASKWhen is the next planned assessment?
LOOK AHEADWhich options apply to our embryos?
You can take this one step at a time.
A picture or unfamiliar term can raise more questions. Write them down and ask your fertility team what the observation means in your own cycle.
Sources and notes about this page
- NHS · Egg collection
- Cambridge IVF · Development in the laboratory
- ESHRE · Good practice in IVF laboratories (2015)
- NHS · Fertilisation in the laboratory
- HFEA · ICSI explained
- HFEA · Decisions about embryos
- HFEA · Embryo freezing
- HFEA · What PGT-A examines
- HFEA · Time-lapse imaging and incubation
Educational overview, not a laboratory operating protocol or personal treatment plan. Timings and clinical decisions vary. AI-generated illustrations are approximate, not to scale, and cannot be used to grade embryos or assess a pregnancy.
By Manoj Kumar K, Embryologist · Inside Embryo. Medical disclaimer