What is the gouge -like space between the nose and the upper lip called?

Cleft
Palate cleft I think.

It's the philtrum but this post is from 2003. That's over four years ago!! :eek:

May be the person didn't know even now ;) or some one else can benefit also.

What is yolk in emryo?explain in detail.
What is its role ?
Please explain mechanism of gastrulation?

what is yolk in emryo?explain in detail.
what is its role ?
please explain mechanism of gastrulation?

Gulia
This should be posted in a separate thread, since it's a new question.
Also, it sounds like a test or homework question. We can help you, but won't do it for you. I will help you if you start working on these questions yourself.

How do you think the yolk would be useful to a chick embryo?
Hint: the yolk is high in fat and protein.

Try to answer and I will give you feedback.