The antibody allowed the isolation of an almost > 95% pure population of osteocytes from calvariae of 18-day-old chicken fetuses

using immunomagnetic separation [2], and the study of characteristics and properties of these osteocytes [4]. Using this antibody it was shown for the first time that isolated see more osteocytes are much more responsive to mechanical load in the form of pulsating fluid flow than osteoblasts or periosteal fibroblasts [5]. Osteocytes are the pivotal cells orchestrating the biomechanical regulation of bone mass and structure for efficient load bearing [5], [6], [7], [8] and [9]. The mechanosensitive osteocytes comprise 90-95% of the whole bone cell population in the adult animal [10]. Within the hard mineralized matrix, osteocyte cell bodies reside

in the spaces called the lacunae. From each osteocyte cell body, approximately 50–60 cell processes originate and radiate through the mineralized matrix via spaces called the canaliculi. Together these structures are called the lacuno-canalicular system (LCS). These cell processes radiate in different directions and form an intricate intercellular network of osteocytes (Fig. 2), which is directly connected to the cells lining the bone surface and cells within the bone marrow [11], [12] and [13]. How the osteocytes sense the mechanical loads on bone and coordinate adaptive alterations in bone mass and architecture is not yet completely understood. However, it is widely accepted that mechanical learn more loads placed on bones as an organ drive a flow of interstitial fluid through the unmineralized Cobimetinib pericellular matrix surrounding osteocytes and their dendritic processes [9] and [14]. This

flow is then thought to somehow activate the osteocytes, which produce signaling molecules that can regulate the activity of the effector cells [15] and [16], the osteoclasts and the osteoblasts, leading to adequate bone mass and architecture [17] (Fig. 3). Over the past two decades theoretical and experimental studies have contributed in delineating the role of osteocytes in mechanosensation and their subsequent biological response. New insights have emerged from an enhanced understanding of the anatomical details of the primary osteocytes [4], [11], [13] and [18], osteocyte isolation [2] and [19], mechanosensation [20], and signal transduction [21], [22], [23] and [24], to name just a few of these advances. Computational models have demonstrated the importance of mechanical loading as a potent and stable regulator of complex biochemical processes involved in maintenance of bone architecture [17]. If osteocytes, acting as the bone mechanosensors, indeed orchestrate the adaptation of bone to mechanical loading, the question arises how this biological action is performed.