Question

Is the embryo formed after the 16-celled embryo (morula) known as Blastocyst? Once it is attached to the endometrium is it called something else?

Answer 1

• Blastocyst differs from morula. The blastocyst develops from the morula.
• The zygote first divides into two identical cells (blastomeres). They continue to subdivide once every 12 to 20 hours as the zygote slowly passes down the fallopian tubes. It develops into a morula and blastocyst. About 3 days after conception the zygote consists of about 16 cells and is called a 16 cell. Morulla is a solid ball of about 16 undifferentiated, spherical cells within the zona pellucid.
• Around 5 days after conception a cavity appears in the center of the morula. The grouping of cells is now called a blastocyst.
• The blastocyst has fully attached itself to endometrium. When the blastocyst implants itself in the inner wall of the uterus it is termed as start of pregnancy.