Ques. 1AIPMT 2003
During embryonic development, the establishment of polarity along anterior/posterior, dorsal/ventral or medial/lateral axis is called:
- Organizer phenomena
- Pattern formation
- Axis formation
- Anamorphosis
Answer
(1) Organizer phenomena
Solution
The organizer is a specialised region of the early embryo (e.g. the dorsal lip of the blastopore, Spemann's organizer) that induces and directs the development of the surrounding undifferentiated tissue.
∴ The organizer sets up the main body axes of the embryo — anterior/posterior, dorsal/ventral and medial/lateral — and this establishment of polarity is called organizer phenomena.
Anamorphosis is development in which segments are added after hatching, so it is not related to axis polarity.
Answer: (1)