Tiered Mentoring Program

Note: Any student chosen for this project will be responsible for providing their own transportation to Northeast Ohio Medical University (NEOMED).

Abstract: As mammalian limbs elongate during skeletal development, some cartilaginous epiphyses can be briefly nourished by blood vessels. This vasculature is not maintained, and mammalian cartilage is classically considered avascular with nourishment provided by diffusion from nearby vessels outside the cartilage. Contrary to most mammals, whales appear to maintain blood vessels within the cartilage of their limb bones. This proposal aims to document the phenotype of blood vessels within the cartilage of whales.  Fixed tissues collected from whales in the Arctic and California will be sectioned and stained to document the extent of blood vessel penetration from an ontogenetic perspective. We expect that by using whales as a case-study, results will add a critical understanding of the mechanisms contributing to a novel cartilage physiology within mammals. 

 Cartilage is essential for the growth and elongation of limb bones. During development, limb bones begin as cartilaginous anlagen and are ultimately replaced by bony tissue. Proliferation and hypertrophy of cartilage cells, called chondrocytes, are the mechanisms that allow for bones to increase their length. Chondrocytes are immersed within a compressible cartilaginous matrix of collagens and proteoglycans and are nourished by diffusion of nutrients through the matrix from nearby vessels outside the cartilaginous tissue.  Cartilage of mammals is classically considered avascular and is unable to regenerate.

 This study will broaden our understanding of the physiology of cartilage by documenting the phenotype and potentially gene expression of the epiphyses of whales from comparative and ontogenetic perspectives. The Cooper Lab at NEOMED has amassed a sample of rare cartilage samples of bowhead, fin, minke, and beluga whales.  These fixed tissues are available for histological processing, sectioning, staining, and image analysis.  If phenotypes can be documented in a reasonable timeframe, the researcher will also collect key comparative data on the gene expression that differentiates the developing whale cartilage from that of terrestrial mammals, including mice and pigs.

The researcher will be trained to participate in every phase of project research, including specimen preparation and analyses. Fixed tissues will be embedded in paraffin wax, sectioned, mounted on slides, and stained to differentiate the vessels, matrix and, chondrocytes. This protocol is already established in the PIs lab.  Using imaging software, images of vessels will be digitized and measured, and form the basis for a quantitative study of vasculature in whales.  Our findings will lay the foundation for future work documenting the novel physiology of whale cartilage.