2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/3580We trace the evolution of a spherically symmetric density perturbation in the MOdified Newtonian Dynamics (MOND) model. The background cosmological model is a $Λ$-dominated, low-$Ω_b$ Friedmann model with no Cold Dark Matter. We include thermal processes and non-equilibrium chemical evolution of the collapsing gas. We find that the first density perturbations which collapse to form luminous objects have mass $\sim 10^5 M_{\odot}$. The time of the final collapse of these objects depends mainly on the value of the MOND acceleration $a_0$ and also on the baryon density $Ω_b$. For the "standard" value $a_0=1.2\times 10^{-8}$ cm/s$^2$ the collapse starts at redshift $z \sim 160$ for $Ω_b=0.05$ and $z \sim 110$ for $Ω_b=0.02$.12 pages, 7 figures, talk presented at the XXV School of Theoretical Physics, Ustron, Poland, 9-16 Sept. 2001, to appear in Acta Physica Polonica BAstrophysicstext