[ Eq(Derivative(x1, t), ((-1)*k1*k3*x1/(x1 + k4*(1 + x2/k5 + x6/k6 + x9/k7 + x21/k8 + k78/k9)) + 1*k1*k35*x13*x16/((x13 + k36*(1 + x2/k37 + x1/k38 + x21/k39))*(x16*(1 + x17/k40) + k41*(1 + x17/k42))))/k1),
  Eq(Derivative(x2, t), (2*k1*k3*x1/(x1 + k4*(1 + x2/k5 + x6/k6 + x9/k7 + x21/k8 + k78/k9)) + (-1)*k1*(k10*x2*x16 - k11*x3*x17) + (-1)*k1*k60*x2/(x2*(1 + k61/k81) + k62*(1 + (1 + k61/k81)*(x21/k63 + x4/k64 + x5/k65))))/k1),
  Eq(Derivative(x3, t), (1*k1*(k10*x2*x16 - k11*x3*x17) + (-1)*k1*(k12*x3*k78*k80 - k13*x4*k79*x21))/k1),
  Eq(Derivative(x4, t), (1*k1*(k12*x3*k78*k80 - k13*x4*k79*x21) + (-1)*k1*(k14*x4 - k15*x5) + (-1)*k1*(k16*x5*x4 - k17*x6) + (-1)*k1*(k22*x4*x7 - k23*x11*x8) + (-1)*k1*(k29*x4*x10 - k30*x11*x12) + (-1)*k1*k66*x4/(x4*(1 + k67/k81) + k68*(1 + (1 + k67/k81)*(x21/k69 + x2/k70 + x5/k71))))/k1),
  Eq(Derivative(x5, t), (1*k1*(k14*x4 - k15*x5) + (-1)*k1*(k16*x5*x4 - k17*x6) + (-1)*k1*(k24*x5*x8 - k25*x9) + (-1)*k1*k72*x5/(x5*(1 + k73/k81) + k74*(1 + (1 + k73/k81)*(x21/k75 + x2/k76 + x4/k77))))/k1),
  Eq(Derivative(x6, t), (1*k1*(k16*x5*x4 - k17*x6) + (-1)*k1*k18*x6/(x6 + k19*(1 + x7/k20 + x21/k21)))/k1),
  Eq(Derivative(x7, t), (1*k1*k18*x6/(x6 + k19*(1 + x7/k20 + x21/k21)) + (-1)*k1*(k22*x4*x7 - k23*x11*x8) + (-1)*k1*(k43*x7 - k44*x14))/k1),
  Eq(Derivative(x8, t), (1*k1*(k22*x4*x7 - k23*x11*x8) + (-1)*k1*(k24*x5*x8 - k25*x9))/k1),
  Eq(Derivative(x9, t), (1*k1*(k24*x5*x8 - k25*x9) + (-1)*k1*k26*x9/(x9 + k27*(1 + x21/k28)))/k1),
  Eq(Derivative(x10, t), (1*k1*k26*x9/(x9 + k27*(1 + x21/k28)) + (-1)*k1*(k29*x4*x10 - k30*x11*x12))/k1),
  Eq(Derivative(x11, t), (1*k1*(k22*x4*x7 - k23*x11*x8) + 1*k1*(k29*x4*x10 - k30*x11*x12) + (-1)*k1*(k33*x11 - k34*x13))/k1),
  Eq(Derivative(x12, t), (1*k1*(k29*x4*x10 - k30*x11*x12) + (-1)*k1*(k31*x12 - k32*x13))/k1),
  Eq(Derivative(x13, t), (1*k1*(k31*x12 - k32*x13) + 1*k1*(k33*x11 - k34*x13) + (-1)*k1*k35*x13*x16/((x13 + k36*(1 + x2/k37 + x1/k38 + x21/k39))*(x16*(1 + x17/k40) + k41*(1 + x17/k42))))/k1),
  Eq(Derivative(x14, t), (1*k1*(k43*x7 - k44*x14) + (-1)*k1*(k45*x14 - k46*x15))/k1),
  Eq(Derivative(x15, t), (1*k1*(k45*x14 - k46*x15) + (-1)*k1*k47*x15*x16/((x15 + k48)*(1 + x17/k50)*(x16 + k49*(1 + k49*x21/(k51*x2 + k52*x7 + k53*x6)))) + 1*k1*k54*x21/(x21 + k55*(1 + x15/k56)))/k1),
  Eq(Derivative(x16, t), ((-1)*k1*(k10*x2*x16 - k11*x3*x17) + (-1)*k1*k35*x13*x16/((x13 + k36*(1 + x2/k37 + x1/k38 + x21/k39))*(x16*(1 + x17/k40) + k41*(1 + x17/k42))) + (-1)*k1*k47*x15*x16/((x15 + k48)*(1 + x17/k50)*(x16 + k49*(1 + k49*x21/(k51*x2 + k52*x7 + k53*x6)))) + 1*k1*k57*x17*x21/((x17 + k58)*(x21 + k59)))/k1),
  Eq(Derivative(x18, t), 0),
  Eq(Derivative(x19, t), 0),
  Eq(Derivative(x20, t), 0),
  Eq(Derivative(x22, t), 0) ]