Neurulation varies depending on the /organism of focus.
-lecith: pertaining to the yolk
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.
Macrolecithal: For example a chick embryo undergoes neurulation at the same time as gastrulation is occuring at different positions at the embryo.