Thaum siv vuam hlau vuam, vuam viav vias viav vias viav vias, vuam hlau txuas yog elongated uniformly, thiab cov txheej txheem vuam ruaj khov. Qhov zoo ntawm weld yuav luag tsis cuam tshuam los ntawm lwm qhov sab nraud, uas txo qhov yuav tsum tau ua ntawm cov tshuab vuam ntawm cov neeg ua haujlwm, yog li ntawd lub vuam zoo yog ruaj khov. Tsis tsuas yog cov kev tsim tawm ntawm kev ua haujlwm ntawm lub vuam tsoo tshuab tau zoo tuaj ntxiv, tab sis kuj tseem muaj qhov zoo ntawm cov hlau txuas tau zoo dua, thiab lub vuam vuam vuam txo.
