Regression of Bone‐Marrow Haemopoiesis from the Terminal Digits in the Foetus and Infant

Estimating the whole bone-marrow asset in humans by a computational approach to integrated PET/CT imaging

“…The application of the method to the most normal population undergoing a whole-body PET/CT scan (subjects with a history of first stage melanoma [42], with no evidence of local or remote disease, and documented absence of relapse over at least 2 years) aimed to build up a reference database for use as a standard by different centres. Although BM evolution in children was not assessed [43], our analysis confirms that active "red" BM does not occupy the whole available space in adults and displays a further progressive slow reduction into old age, starting from the appendicular bones [8][9][10][11]44].…”

Marrow Adipose Tissue: Trimming the Fat

“…The ‘red’ marrow in regions including the lumbar/thoracic vertebrae, proximal limb skeleton, hip and ribs contains the majority of the hematopoietic cells, but can still retain a high volumetric proportion of adipocytes [2,6], known as regulated MAT ( rMAT) (Box 1). Historic observations in rabbits [7] and humans [3,8] and recent work in mice [5] and rabbits [4] support the concept that MAT undergoes differential development and regulation depending on where it is located in the skeleton [5]. …”

“…Combined, this would predict 1142+/−410 cm 3 of total MAT, equivalent to 1.03+/−0.37 kg (fat density = 0.9 g/cm 3 ). Indirect MRI-based techniques concur, revealing that the amount of total MAT in the skeleton of an average size human is ~ 1.35 kg (ranging from 0.5 to 3 kg) [8,10,11], accounting for approximately 8% of total fat mass. Depending on peripheral fat volume, this proportion can range from as low as 1% to as high as ~ 30% [2,12].…”

“…humans > rabbits > rats > mice) [2]. Mice have a significantly reduced proportion of MAT in areas of red marrow, as quantified in three-dimensions using osmium tetroxide staining combined with micro-computed tomography [5,8,12,13]. For example, 12-week-old C57Bl/6J (B6) male mice have on average 0.7% MAT by volume in the bone marrow of the tibial diaphysis [5].…”

Use of Osmium Tetroxide Staining with Microcomputerized Tomography to Visualize and Quantify Bone Marrow Adipose Tissue In Vivo

“…In addition, it is now known that this same BM, in addition to being hematopoietic, is also osteogenic. MAT infiltration accelerates shortly after birth in the distal portions of the appendicular skeleton before developing in more proximal areas (Emery & Follett, 1964). For example, in humans the BM of the middle phalanges of the toes is completely converted to MAT by 12 months of age (Emery & Follett, 1964).…”