The Scofield Bible Commentary, by Cyrus Ingerson Scofield, [1917], at sacred-texts.com
sheep
The sheep for sacrifice were brought in here.
(See Scofield) - (Joh 5:2).
tower
The towers appear to have been on either side the sheep gate.
Nethinims
That is, Dedicated (persons), probably descendants of the Gibeonites (Sa2 21:1-3) devoted to the service of the Levites. But see (Jos 9:17-21).
Ophel
translated, "tower," (Kg2 5:24); (Ch2 27:3); (Ch2 33:14). Perhaps part of the fort called Millo, (Kg1 9:15); (Ch2 32:5).