C
O
 CHOLESTEROL
) 5-PREGNENOLONE
4
2
4
10
1
B
18
19
2
7
8
5
9
10
14
15
16
1
6
B
C
18
12
11
19
7
8
5
9
14
15
16
17
13
C
O
H
3
C
PROGESTERONE
O
6
6
10
9
B
18
19
2
7
8
5
9
10
14
1
C
12
11
13
O
6
10
9
15
17-OH PROGESTERONE
H
3
C
16
 
4
3
  OH