In the recent “February In focus in HCB” editorial, we highlighted three manuscripts focusing on bone and hard tissues (Taatjes and Roth 2025a). Likewise, in the “March In focus in HCB” editorial (Taatjes and Roth 2025b), we highlighted a comprehensive review on the role of stem cells in cartilage regeneration as a potential therapeutic treatment for osteoarthritis (Ciesla and Tomsia 2025). We continue this trend in the current editorial by highlighting a manuscript by He and colleagues (2025) describing a detailed investigation of vascularization in human osteoarthritic femoral heads in elderly patients using advanced stereological methods. Femoral heads were collected from elderly patients (> 70 years of age) presenting with hip osteoarthritis. The samples were then divided into four groups of osteoarthritis severity based upon X-ray examination using the Kellgren–Lawrence (KL) grading system (Kellgren and Lawrence 1957). Upon surgical removal, the samples were subjected to strict stereological procedures (Howard and Reed 2005), beginning with volume calculations and systematic uniform random sampling for subsampling the femoral head specimens. The randomly selected samples were then embedded in Technovit 9100 New, sectioned, and stained with hematoxylin or eosin and Safranin O/Fast Green, or subjected to immunohistochemical staining for anti-CD34 as a marker for blood vessels. Cartilage degeneration was assessed on slides stained with Safranin O/Fast Green using the Mankin grading score of 0 (normal cartilage) to 14 (severe osteoarthritis) (Pauli et al. 2012). Multiple stereological parameters were then assessed on stained slides, including cartilage volume, subchondral region volume, cartilage thickness, chondrocyte and extracellular matrix volumes, subchondral bone and bone marrow volumes, blood vessel volume, blood vessel surface area, and blood vessel length 1 cm below the subchondral layer of the femoral head. In addition, four samples of different KL grades were subjected to micro-computed tomography (microCT) scanning for overlay onto images obtained for histological analysis. Their very rigorous and voluminous (pun intended) quantitative stereological results comparing the samples in the KL1–KL4 patient groups are presented in several tables, but can be briefly summarized as follows: (1) the higher KL grades correlated with both increased subchondral vascularization and more severe cartilage degeneration; (2) vascularization of the subchondral region in osteoarthritic femoral heads occurred prior to actual cartilage degeneration; (3) blood vessel volume was found to increase from the earliest (KL1) to the latest (KL4) stages of osteoarthritis, while blood vessel surface area and vessel length were greatest in the mid-late and late stages compared to the early and mid-stages; and (4) overlaying the microCT three-dimensional image with the histological slide image allowed a precise and detailed interpretation of the spatial organization of the tissue pathology. The take-home message from this rigorously designed and executed study is that tissue vascularization may be involved in the pathological cartilage degradation symptomatic of osteoarthritis. Moreover, the study once again illustrates the power of a well-designed stereological investigation to provide rigorous quantitative morphological data.