Fig. 3
From: Morphological variations of the interatrial septum and potential implications in equine cardiology
Adapted from Holda et al., 20181,2.
Schematic overview of the interatrial septum in the heart. (A) General illustration of the interatrial septum formed by the fusion of the embryonic septum primum and secundum. (B–I) Different morphological presentations of the interatrial septum and their comparative prevalence among species: equine (Eq), human (Hu), porcine (Por), and ovine (Ov). (B) Smooth septum on both the right and left sides; (C) patent foramen ovale (PFO); (D) single left-sided septal pouch (LSP); (E) single right-sided septal pouch (RSP), the most common presentation in horses; (F) double septal pouch (DSP); (G) Double sided septal pouch with the presence of a left-sided septal ridge (LSR); (H) right-sided septal pouch coexisting with a left-sided septal ridge; (I) left-sided septal ridge. LA, left atrium; RA, right atrium.
