diff --git a/src/core.c b/src/core.c
index f27576c..5dd3d55 100644
--- a/src/core.c
+++ b/src/core.c
@@ -141,12 +141,8 @@ void manage_mutation(struct game *current_game, const int mutation_menu)
         
         // Manage input
         if (key == KEY_EXIT) end = 1;
-        if (key == KEY_EXE && table[c.y][c.x] != 15 && table[c.y][c.x] != 0)
-        {
-            mutation_selected(c, mutation_menu, table);
-            getkey();
-        }
-        
+        if (key == KEY_EXE && table[c.y][c.x] != 15 && table[c.y][c.x] != 0) mutation_buy(current_game, c, mutation_menu, table);
+                    
         if (key == KEY_LEFT && c.x > 0) c.x--;
         if (key == KEY_RIGHT && c.x < 7) c.x++;
         if (key == KEY_UP && c.y > 0) c.y--;
@@ -154,3 +150,25 @@ void manage_mutation(struct game *current_game, const int mutation_menu)
     }
     if (t >= 0) timer_stop(t);
 }
+
+
+void mutation_buy(struct game *current_game, const struct cursor c, const int mutation_menu, const int table[4][8])
+{
+    int button_selected = 0, end = 0;
+    int key = 0;
+
+    while (!end)
+    {
+        mutation_selected(c, mutation_menu, table, button_selected);
+        key = getkey().key;
+
+        if (key == KEY_DOWN || key == KEY_UP) button_selected = (button_selected + 1) % 2;
+        if (key == KEY_EXIT) end = 1;
+        if (key == KEY_EXE)
+        {
+            if (!button_selected) end = 1;
+            // else evolution
+        }
+
+    }
+}
diff --git a/src/core.h b/src/core.h
index b6e9545..71e66a8 100644
--- a/src/core.h
+++ b/src/core.h
@@ -76,7 +76,10 @@ int rtc_key(void);
 // callback_timer : basic timer
 int callback_tick(volatile int *tick);
 
-// manage_mutation : an independant sub-programm which allow to select, buy and see the mutations.
-void manage_mutation(struct game *current_game, const int mutation_menu);
+// manage_mutation : an independant sub-programm which allow to select and see the mutations.
+void mutation_select(struct game *current_game, const int mutation_menu);
+
+// mutation_buy : UI interface to buy mutations and see informations on them
+void mutation_buy(struct game *current_game, const struct cursor c, const int mutation_menu, const int table[4][8])
 
 #endif /* _PLAGUE_CORE_H */
\ No newline at end of file
diff --git a/src/display_engine.c b/src/display_engine.c
index 98e4cc9..7280944 100644
--- a/src/display_engine.c
+++ b/src/display_engine.c
@@ -99,7 +99,7 @@ void display_mutation(const int table[4][8], const struct cursor c, const int mu
 }
 
 
-void mutation_selected(const struct cursor c, const int mutation_menu, const int table[4][8])
+void mutation_selected(const struct cursor c, const int mutation_menu, const int table[4][8], const int button_selected)
 {
     extern const bopti_image_t img_mutations;
     const int id = table[c.y][c.x];
@@ -135,7 +135,10 @@ void mutation_selected(const struct cursor c, const int mutation_menu, const int
     dprint(81, 41, C_BLACK, "%d", mutation_data->contagion);
     dprint(81, 49, C_BLACK, "%d", mutation_data->lethality);
     dprint(81, 57, C_BLACK, "%d", mutation_data->severity);
-    
+
+    if (button_selected) drect(81, 2, 123, 8, C_INVERT);
+    else drect(81, 12, 123, 18, C_INVERT);
+
     dupdate();
 
 
diff --git a/src/display_engine.h b/src/display_engine.h
index 23898a9..21670df 100644
--- a/src/display_engine.h
+++ b/src/display_engine.h
@@ -12,7 +12,7 @@ void display_foreground(const int background, const struct game *current_game);
 // display_mutation : display the mutation selection screen
 void display_mutation(const int table[4][8], const struct cursor c, const int mutation_menu);
 
-// mutation_selected : display the mutation shop
-void mutation_selected(const struct cursor c, const int mutation_menu, const int table[4][8]);
+// mutation_selected : display the mutation's informations screen
+void mutation_selected(const struct cursor c, const int mutation_menu, const int table[4][8], const int button_selected);
 
 #endif /* _PLAGUE_DISPLAY_ENGINE_H */
\ No newline at end of file