Context : In general , studies focused on the Milky Way ’ s structure show a range of values when deriving different Galactic parameters such as radial scalelengths , vertical scaleheights , or local space densities .
Those values are also dependent on the Galactic coordinates under consideration for the corresponding analysis , as a direct consequence of be observing a structure ( Our Galaxy ) , that is far from being as smooth and well-behaved as models usually consider .

Aims : In this paper , we try to find any dependence of the Galactic structural parameters with the Galactic longitude for either the thin disc or the thick disc of the Milky Way , that would indicate to possible inhomogeneities or asymmetries in those Galactic components .

Methods : Galactic model parameters have been estimated for a set of 36 high-latitude fields with Two Micron All Sky Survey ( 2MASS ) photometry .
Possible variations with the Galactic longitude of either the scaleheight and the local space density of these components are explored .

Results : Galactic model parameters for the different fields show that , effectively , they are Galactic longitude-dependent .
The thick disc scaleheight changes from \sim 800 pc at 150 ^ { \circ } < l < 230 ^ { \circ } to \sim 1050 pc at |l| < 30 ^ { \circ } .
A plausible explanation for this finding might be the effect of the flare in this Galactic component that changes the scaleheight ( h _ { z } ) with Galactocentric distance ( R ) following the approximate law : h _ { z } ( R ) = ( 940 \pm 20 ) \times [ 1 - ( 0.12 \pm 0.02 ) ( R - R _ { \odot } ) ] .
The effect of the flare is more stressed in some lines of sight than in others , producing the observed changes in the parameters with the Galactic coordinates used to derive them .

Conclusions :