How to enumerate all the users in Active Directory

I wrote following C# code to enumerate all the employess and it is working fine. Now i want to filter the users by OU name.  Is there a way by which i can filter by OU.

 using (var context = new PrincipalContext(ContextType.Domain, "mydomainname.net"))
            {
                using (var searcher = new PrincipalSearcher(new UserPrincipal(context)))
                {
                    foreach (var result in searcher.FindAll())
                    {
                        DirectoryEntry de = result.GetUnderlyingObject() as DirectoryEntry;
                        Console.WriteLine("First Name: " + de.Properties["givenName"].Value);
                        Console.WriteLine("Last Name : " + de.Properties["sn"].Value);
                        Console.WriteLine("SAM account name   : " + de.Properties["samAccountName"].Value);
                        Console.WriteLine("User principal name: " + de.Properties["userPrincipalName"].Value);
                        Console.WriteLine();
                    }
                }
            }
            Console.ReadLine();