I. INTRODUCTION The question of how the electronic structure of high- T$_{c}$ cuprates evolves from the Mott insulator to the superconductor with hole doping is one of the most fundamental and im- portant issues in condensed matter physics. This subject has been extensively investigated experimentally and theoretically, but still remains highly controversial. Previous angle- resolved photoemission spectroscopy (ARPES) studies have revealed two different cases. In underdoped La$_{2}$$_{−}$$_{x}$Sr$_{x}$CuO$_{4}$ (LSCO), a “two-component” electronic structure has been ob- served, that is, upon hole doping “in-gap” states appears primarily well ( ∼ 0.4 eV) above the lower Hubbard band (LHB), the chemical potential does not shift and spectral weight is transferred from the LHB to the in-gap states for further hole doping within the un- derdoped region $^{1–3}$. Already in the lightly-doped region, a weak quasi-particle (QP) peak crosses the Fermi level ( E$_{F}$ ) in the (0,0)-( π, π ) nodal direction and is responsible for the metallic transport $^{2}$. ARPES spectra of underdoped Ca$_{2}$$_{−}$$_{x}$Na$_{x}$CuO$_{2}$Cl$_{2}$ (Na-CCOC) 4 and Bi$_{2}$Sr$_{2}$$_{−}$$_{x}$La$_{x}$CuO$_{6+}$$_{δ}$ (Bi2201) $^{5}$, on the other hand, show that upon hole doping the chemical potential moves to the top of the LHB and continues to shift downward for further hole doping. As for the Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+}$$_{δ}$ (Bi2212) family, the apparently smooth evolution of ARPES spectra in the ( π, 0) region in a combined plot of undoped Ca$_{2}$CuO$_{2}$Cl$_{2}$ (CCOC) and un- derdoped Bi2212 implies that a behaviour similar to Na-CCOC is expected for Bi2212 $^{6}$. A core-level photoemission study of Bi2212 has indeed shown that the chemical poten- tial is shifted with doping in underdoped samples 7 unlike LSCO. Recently, a momentum distribution curve (MDC) analysis of Bi2201 5 and underdoped Na-CCOC 8 have revealed the existence of an additional QP band just above the LHB crossing E$_{F}$ . Here, strong electron-phonon interaction has been proposed to result in the dressed coherent QP band accompanied by a high-energy incoherent (Frank-Condon type) feature. Yet, the different behavior of the chemical potential shift and the LHB-QP energy separation between LSCO and Na-CCOC or Bi2201 remains to be explained. In order to see what makes those dif- ferences between the different families in the evolution of the electronic structure from the Mott insulator to the superconductor, we have performed detailed APRPES measurements of lightly-doped Bi2212. 2