The temperature dependences of the in-plane resistivity _ab(T ) and out-of-plane resistivity _c(T ) in Bi-2212 crystals covering the region from the underdoped to the overdoped regime have been measured. In the underdoped regime, _ab(T ) deviates from a linear temperature dependence below a characteristic temperature T ^*, well above T_c, whose value decreases with increasing hole concentration. For underdoped crystals, _ab(T) shows a typical S-shaped temperature dependence and _ab = ₀^*+exp(-/T ) is satisfactorily obeyed over a much wider temperature range from slightly above T_c up to T ^*. Near the optimal region, the T -linear dependence of _ab(T ) is maintained over a wide temperature interval. In contrast, a power law _ab~Tⁿ (n = 1.5-1.8) is followed in the overdoped regime. As regards the out-of-plane resistivity, on the other hand, _c(T ) for the underdoped Bi₂Sr₂CaCu₂O_y crystals shows a semiconductive behaviour, which is well described by the formula _c = (C₁/T)exp(C₂/T ) + C₃T + C₄. The difference between the temperature dependences of _c(T ) in the overdoped Bi₂Sr₂CaCu₂O_y and Bi_1.85Pb_0.15Sr₂CaCu₂O_{8 +} crystals, with basically the same values of T_c and nearly the same power-law temperature dependences of _ab(T ) (_ab~T ^1.4), reveals that the inter-plane disorder in the form of oxygen vacancies and substituted cations acting as an extra blocking layer plays an important role in out-of-plane transport.