collagenous

https://doi.org/10.1351/goldbook.10544

Rich in the fibrous connective tissue protein, collagen.

Source:
PAC, 2016, 88, 713. 'Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)' on page 738 (https://doi.org/10.1515/pac-2015-1202)