T3 Respiratory Developmental Tutorial

Question 1

Explain the terms “totipotent” and “pluripotent”.

Answer 1

Both refer to the potential of cells.

Totipotent means a cell has not begun differentiating and has the potential to develop into any other cell.

Pluripotent refers to a cell that has begun to differentiate but still has options for the future.

Question 2

Describe the hypoblast and epiblast

Answer 2

The hypoblast and epiblast are bilaminar embryonic discs that develop around day 8 of fertilisation.

The hypoblast gives rise to the endoderm and the epiblast gives rise to the ectoderm (skin).

Question 3

Explain gastrulation

Answer 3

Around day 15, gastrulation takes place. This is the formation of three distinct layers:

• ectoderm
• mesoderm
• endoderm

The ectoderm forms the primitive node and the cells move in and ‘sink’ between ectoderm and endoderm, forming the mesoderm.