Theodoret of Cyrus

It is very likely that these words refer to the womb of the Virgin, through which no one enters and from which no one departs other than the only one who is the Lord.

Commentary on Ezekiel 16.44

Augustine of Hippo

What means this closed gate in the House of the Lord, except that Mary is to be ever inviolate? What does it mean that 'no man shall pass through it,' save that Joseph shall not know her? And what is this - 'The Lord alone enters in and goeth out by it' - except that the Holy Ghost shall impregnate her, and that the Lord of angels shall be born of her? And what means this—'it shall be shut for evermore' - but that Mary is a virgin before His Birth, a virgin in His Birth, and a virgin after His Birth?

De Annunt. Dom. iii ↗

Ambrose of Milan

What is that gate of the sanctuary, that outer gate facing the east and remaining closed? Is not Mary the gate through whom the Redeemer entered this world?

Letter 44 ↗

Jerome

For before the Savior assumed a human body and humbled himself, taking on the form of a servant, the Law and the Prophets, and all the knowledge of the Scriptures, were closed, and paradise was closed. But after he hung on the cross, and spoke to the thief, 'Today you will be with me in paradise' (Luke 23:43), immediately the veil of the temple was torn, and everything was opened; and with the veil removed, we say: But we all, with unveiled face, beholding the glory of the Lord, are being transformed into the same image, from glory …

Commentary on Ezekiel ↗