encierran

They delimit and enclose a nucleus endowed with certain factors of its own.

third-person plural present indicative of encerrar

to lock up, to coop up
to lock away, put away, to imprison, to nail (in a prison or mental hospital)
to enclose, to confine, to immure
to contain, to hold, to include, to encapsulate, to entail
to stalemate
to separate (between brackets, commas)
(reflexive) to take over; occupy (a building)
(reflexive) to shut oneself up, to withdraw, to shut away oneself, to shut off oneself, to lock up or lock down oneself, to close off oneself
(reflexive) to shy away