Neurulation varies depending on the /organism of focus.
Key terms:
-lecith: pertaining to the yolk
micro: small
meso: moderate
macro: large
Microlecithal: For example an amphioxus embryo undergoes neurulation as a step on it’s own – nothing else is happening except for the neurulation.
Mesolecithal: For example a frog embryo undergoes neurulation after gastrulation as a process on its own. Nothing else is going on EXCEPT the neurulation.
(http://crescentok.com/staff/jaskew/isr/botzo/chordate1(dot)jpg)
Macrolecithal: For example a chick embryo undergoes neurulation at the same time as gastrulation is occuring at different positions at the embryo.
(http://www.mun.ca/biology/desmid/brian/BIOL3530/DEVO_03/ch03f16(dot)jpg)
