Comparison of present-day and inferred initial stellar densities of typical regions. All seven regions evolve to lower densities away from their initial values. Ranges for the present-day densities are calculated from the total stellar masses and half-mass radii reported in Sect. 3. USco-A is not plotted here as no present-day radius with a given enclosed mass is reported in the literature that could reasonably be compared to the half-mass densities of its initial configuration constrained here. Note that some mass estimates only cover a limited spectral-type range. The filled circles indicate the deduced initial conditions for some Galactic GCs (Marks & Kroupa 2010).