Presence of the annular ridge and location of the coronary sinus ostium as morphological features of the right atrium and interatrial septum in healthy common marmosets (<i>Callithrix jacchus</i>)

Abstract

To effectively use a common marmoset (Callithrix jacchus) as an experimental animal species, it is critical to establish a normal characteristics and morphology of the organs of the common marmoset. Although gross morphology of the common marmoset heart is reportedly the same as that of humans, little information is available regarding detailed morphology of the right atrium and the interatrial septum. Heart specimens were collected from three male and 10 female marmosets aged 9 to 65 months to determine the morphological features of the right atrium and the interatrial septum. Ten specimens were evaluated morphologically with a stereoscopic microscope in accordance with preparation and investigation methods designed to facilitate evaluation. Three specimens were histologically evaluated after being stained with hematoxylin-eosin, Elastica van Gieson and periodic acid Schiff. An annular ridge that is not present in the human heart was present in the right atrium and the interatrial septum of the common marmoset hearts. Tissue structure of the annular ridge was similar to atrial myocardial fibers. Furthermore, location of the coronary sinus ostium was different to that in humans. Present findings were used to create a schematic view of the annular ridge in the common marmoset heart. In the common marmoset heart, the annular ridge may function as a valve of the superior vena cava ostium, inferior vena cava ostium, and coronary sinus ostium. Present study provides morphological evidence that common marmosets have a valve-like structure in the right atrium.

Functional Cardiovascular Characterization of the Common Marmoset (Callithrix jacchus)

“…The use of NHPs like common marmosets raises some ethical concerns [ 36 ] and they have, in general, a lower availability than small rodents for research. Additionally, the common marmoset differs from the human situation with regard to its higher heart rate and slight differences in cardiac anatomy [ 37 ]. The facts that the possibilities for genetic modifications are currently not yet as advanced as for rodent species and that there are fewer amounts of available cross-reacting antibodies did limit their broader use in comparison to other animal species in the past [ 38 , 39 ].…”