Persistence of a functioning bulbus cordis homologue in the turtle heart

• Published in: The American journal of physiology Vol. 201; no. 6; pp. 1109 - 1112
• Main Author: March, Harold W
• Format: Journal Article
• Language: English
• Published: United States 01-12-1961
• Subjects: Animals; Heart - anatomy & histology; Histological Techniques; Humans; Old Medline; Reptiles - anatomy & histology; Turtles; HEART/anatomy and histology; REPTILES/anatomy and histology
• ISSN: 0002-9513; 2163-5773
• DOI: 10.1152/ajplegacy.1961.201.6.1109

1 Department of Medicine, Stanford University School of Medicine, Palo Alto, California
The functional and structural characteristics of a discrete myocardial segment at the base of the turtle ventricle were studied. The study indicates that this segment is a homologue of the primitive bulbus cordis. Cinematographic techniques were utilized to observe the function of this segment. It contracts later than the main ventricular chamber and acts as a sphincter at the base of the pulmonary artery in late systole. It is suggested that this mechanism serves to regulate the normal left-to-right shunt into the lungs through the incomplete ventricular septum and to maintain adequate systemic blood flow. A resemblance between the arrangement in the turtle and that seen in certain cases of human congenital heart disease is briefly discussed.