Partial failure to completely reabsorb the septum after Mullerian duct fusion results in the structure known as subseptae.

• A. Septae
• B. Subseptae
• C. Unicornuate
• D. Didelphys

Answer: (B)

Subseptae describe a partial persistence of the midline septum inside the uterus after Müllerian duct fusion. During development, the two ducts fuse to form the uterus and the intervening septum is normally reabsorbed to create a single cavity. If this resorption halts partway, a residual partial septum remains within the cavity, giving subseptae. This is different from a full septum, which would indicate the septum extended all the way through the cavity from fundus to cervix. If fusion fails entirely, you’d see a didelphys uterus with two separate cavities, and if one duct doesn’t develop, a unicornuate uterus results. So subseptae specifically reflect incomplete resorption after fusion, producing a partial internal septum.