If by "consistency," you mean whether it's red cellular marrow vs yellow fatty

If by "consistency," you mean whether it's red cellular marrow vs yellow fatty marrow, the latter naturally increases over time. There is a predictable pattern of distribution of the decrease in red marrow over time. Diagrams of such are available, such as the following: The 1st demonstrates the typical distribution of red cellular marrow (i.e. that capable of generating blood elements,) in an Infant and an Adult. To its right is a schematic of an adult left femur demonstrating the two types of normal marrow. The 3rd & 4th schematics demonstrate the conversion of red marrow to yellow fatty marrow over time. Bone marrow stem cells The bone marrow contains two types of stem cells, mesenchymal and hematopoietic. Red bone marrow consists of a delicate, highly vascular fibrous tissue containing hematopoietic stem cells. These are blood-forming stem cells. Yellow bone marrow contains mesenchymal stem cells, also known as marrow stromal cells. These produce fat, cartilage, and bone.4 Bone marrow timeline Before birth, bone marrow first develops in the clavicle toward the end of fetal development. It becomes active about 3 weeks later. Bone marrow takes over from the liver as the major hematopoietic organ at 32 to 36 weeks' gestation. Bone marrow remains red until around the age of 7 years, as the need for new continuous blood formation is high. As the body ages, the red marrow is gradually replaced by yellow fat tissue. Adults have an average of about 2.6 kg (5.7 lbs) of bone marrow, about half of which is red.3 In adults, the highest concentration of red marrow is in the bones of the vertebrae, hips (ilium), breastbone (sternum), ribs, skull and at the metaphyseal and epiphyseal ends of the long bones of the arm (humerus) and leg (femur and tibia). All other cancellous, or spongy, bones and central cavities of the long bones are filled with yellow marrow. Introduction Gelatinous tissue found in the inner spaces of bone that contains progenitor cells and stromal cells Types of bone marrow red marrow hematopoietic tissue composition 40% water 40% fat 20% protein yellow marrow fatty tissue composition 15% water 80% fat 5% protein Function primary function of hematopoiesis controls the inner diameter of bone Red Bone Marrow Location most commonly found in flat bones ribs, ilium, sternum, vertebrae, skull epiphysis/metaphysis of long bone (children only) Function contains mesenchymal stem cells and hematopoietic stem cells red marrow slowly changes to yellow marrow with age Yellow Bone Marrow Location most commonly found in diaphysis or shaft of long bones femur, humerus, tibia Function contains mostly fat cells may revert to red bone marrow if there is an increased demand for red blood cells (e.g. trauma) Bone Marrow Examination Biopsy location anterior or posterior iliac crest sternum tibia indications malignancies (most common) multiple myeloma, lymphoma, leukemia, metastatic disease infection TB (rare) technique needle/trochar biopsy open surgical biopsy Clinical Aspects of Cell Therapy Bone Marrow Aspirate applications in orthopedic surgery fracture union/non-union osteonecrosis mesenchymal tissue engineering (e.g., bone, ligaments, cartilage) uploads/s3/ trigger-guide.pdf

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