Draw the following diagrams related to human reproduction and label them.

• a) The zygote after the first cleavage division
• b) Morula stage
• c) Blastocyst stage (sectional view)

Here are descriptions of the diagrams related to human reproduction, along with their labels:

Zygote After the First Cleavage Division

The zygote is a single cell formed after the fertilization of an egg by a sperm. After the first cleavage division, it divides into two smaller cells called blastomeres. This stage marks the beginning of embryonic development.

• Zygote: The fertilized egg.
• Blastomeres: The two cells formed after division.

Morula Stage

The morula is a solid ball of cells that forms after several rounds of cleavage divisions. It typically consists of 16 to 32 cells and resembles a mulberry, hence the name "morula." At this stage, the cells are still tightly packed together.

• Morula: The solid mass of cells.
• Cells: Individual cells that are dividing and compacting.

Blastocyst Stage (Sectional View)

The blastocyst stage occurs a few days after the morula stage. It features a hollow structure with an inner cell mass that will develop into the embryo and an outer layer called the trophoblast, which will form part of the placenta.

• Blastocyst: The hollow structure.
• Inner Cell Mass: The group of cells that will become the embryo.
• Trophoblast: The outer layer that helps in implantation.

These stages are crucial in understanding the early development of a human embryo.