Chimpanzees Heart

Some Chimpanzees Have Tiny Bone in Their Heart

A team of researchers in the UK has discovered that some individuals of the common chimpanzee (Pan troglodytes), particularly those affected by myocardial fibrosis, have a rare small bone called os cordis in their heart.

High-resolution microCT image of the chimpanzee’s os cordis. Image credit: Moittié et al, doi: 10.1038/s41598-020-66345-7.

The presence of an os cordis is a regular finding in large ruminants such as cattle, ox, water buffalos and sheep. Otters and camels sometimes have this bone too. But this is the first time that the os cordis has been discovered in a great ape.

Cartilage (cartilago cordis) can also be present within the cardiac skeleton of individuals of other animal species such as horses, pigs, dogs, cats, mice, rats, snakes, white rhinoceros and Syrian hamsters.

Although the exact localization, size and number of the os cordis varies, in all species it lies within a band of fibrous tissue called trigonum fibrosum.

Its function is unclear but it is believed to serve as a pivot and anchoring support for the heart valves.

“The discovery of a new bone in a new species is a rare event, especially in chimps which have such similar anatomy to people,” said study’s senior author Dr. Catrin Rutland, a researcher in the School of Veterinary Medicine and Science at the University of Nottingham.

“It raises the question as to whether some people could have an os cordis too.”

Dr. Rutland and colleagues compared the structure and morphology of 16 hearts from chimpanzees which were either healthy or affected by myocardial fibrosis, a type of heart disease found in chimps and people.

To study the organs, the researchers used X-ray microtomography (microCT), a non-destructive X-ray imaging technique that produces 3D images from 2D trans-axial projections.

They found the os cordis bones, measuring a few millimeters in size, and cartilago cordis in four hearts. Their presence was not associated with age nor with sex.

“Looking for ways to help chimps with heart disease is essential,” said first author Dr. Sophie Moittié, from the School of Veterinary Medicine and Science at the University of Nottingham and Twycross Zoo.

“Understanding what is happening to their hearts helps us manage their health.”

“This research has brought together researchers and veterinary professionals, working on a common aim to advance chimpanzee health and conservation,” Dr. Rutland said.

The discovery is described in a paper published in the journal Scientific Reports.

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S. Moittié et al. 2020. Discovery of os cordis in the cardiac skeleton of chimpanzees (Pan troglodytes). Sci Rep 10, 9417; doi: 10.1038/s41598-020-66345-7