[ Eq(Derivative(x1, t), (1*k16*k3 + 1*k16*k9*x2 + (-1)*(k6*x1*x6/(1 + k1*x6) + k7*x1*(x4 + x3)/(1 + k2*(x4 + x3))) + (-1)*k16*k4*x1)/k16),
  Eq(Derivative(x2, t), ((-1)*k16*k9*x2 + 1*(k6*x1*x6/(1 + k1*x6) + k7*x1*(x4 + x3)/(1 + k2*(x4 + x3))) + (-1)*k16*k4*x2 + (-1)*k16*k8*k10*x2 + (-1)*k16*(1 - k8)*k10*x2)/k16),
  Eq(Derivative(x3, t), (1*k16*k8*k10*x2 + (-1)*k16*(k4 + k11)*x3 + (-1)*k16*k12*x3)/k16),
  Eq(Derivative(x4, t), (1*k16*(1 - k8)*k10*x2 + (-1)*k16*(k4 + k11)*x4 + (-1)*k16*k13*x4)/k16),
  Eq(Derivative(x5, t), (1*k16*k12*x3 + 1*k16*k13*x4 + (-1)*k16*k4*x5)/k16),
  Eq(Derivative(x6, t), (1*(k15*x4 + k14*x3) + (-1)*k17*k5*x6)/k17) ]