THE MORULA
After the zygote undergoes a few rounds of division, it is known as a morula.
- A morula contains about 10 – 30 cells.
- The morula stage is the final stage prior to the formation of a fluid filled cavity known as the BLASTOCOEL CAVITY.
- Once the cavitation has occurred, we can see the fluid in the cavity between the cells and we call the embryo an early BLASTOCYST.
- Although the morula stage embryos are usually seen on day 4 and the blastocysts are usually seen on day 5, sometimes we have only morulas on day 5.
- In that case, we do not know if the embryos are slower than average because they are weaker, or because they are healthy, but just developing slower than average.
- Transferring morulas on day 5 results in a reasonable pregnancy rate, although it is not as high as the pregnancy rate with blastocyst transfers on day 5.
ASHLEY'S COSMOS 