Number of dopaminergic neurons in VTA
Approximately, 250000-440000 neurons in Humans (Rice et al., 2016). 


  The substantia nigra/ventral tegmental area (SN/VTA) complex is a
  heterogeneous collection of dopaminergic cell groups that extends from
  diencephalic to mesencephalic territories in many vertebrates,
  including rodents, non-human primates, and humans (Puelles and Verney
  1998; see as reviews Smits et al. 2006; Smidt and Burbach 2007; Smits
  et al. 2013). The SN/VTA contains the largest number of dopaminergic
  neurons in the brain (see as reviews van Domburg and ten Donkelaar
  1991; Haber and Fudge 1997; Nieuwenhuys et al. 2008), with average
  estimates ranging in most studies from approximately 250,000 –
  440,000 dopaminergic neurons within the complex (Bogerts et al.
  1983; Hirsch et al. 1988; van Domburg and ten Donkelaar 1991; Damier
  et al. 1999a; Kubis et al. 2000).