Ever wondered what actually exists in our skull bone and also in brain ?! We probably can’t even detect and analyse that things due to it’s complex structure and also the most sensitive element of our body. But it’s not just alone part of the body that comprise bone related tissues as we have same structural knowledge of other bones also.
Actually we have bone marrow, the spongy tissue inside most of our bones, produces red blood cells as well as immune cells that help fight off infections and heal injuries. Also the new study of brain and skull bone has something to say about that.
“We always thought that immune cells from our arms and legs traveled via blood to damaged brain tissue. These findings suggest that immune cells may instead be taking a shortcut to rapidly arrive at areas of inflammation,” said Francesca Bosetti, Ph.D., program director at the NIH’s National Institute of Neurological Disorders and Stroke (NINDS), which provided funding for the study. “Inflammation plays a critical role in many brain disorders and it is possible that the newly described channels may be important in a number of conditions. The discovery of these channels opens up many new avenues of research.”
Using state-of-the-art tools and cell-specific dyes in mice, Matthias Nahrendorf, M.D., Ph.D., professor at Harvard Medical School and Massachusetts General Hospital in Boston, and his colleagues were able to distinguish whether immune cells traveling to brain tissue damaged by stroke or meningitis, came from bone marrow in the skull or the tibia, a large legbone. In this study, the researchers focused on neutrophils, a particular type of immune cell, which are among the first to arrive at an injury site.
During the observation Dr. Nahrendorf’s aslso discovered that six hours after stroke, there were fewer neutrophils in the skull bone marrow than in the tibia bone marrow, suggesting that the skull marrow released many more cells to the injury site. These findings indicate that bone marrow throughout the body does not uniformly contribute immune cells to help injured or infected tissue and suggests that the injured brain and skull bone marrow may “communicate” in some way that results in a direct response from adjacent leukocytes.
ABOUT BRAIN STRUCTURE
The adult human brain weighs on average about 1.2–1.4 kg (2.6–3.1 lb) which is about 2% of the total body weight, with a volume of around 1260 cm3 in men and 1130 cm3 in women, although there is substantial individual variation.Neurological differences between the sexes have not been shown to correlate in any simple way with IQ or other measures of cognitive performance.
The cerebrum, consisting of the cerebral hemispheres, forms the largest part of the brain and is situated above the other brain structures.The outer region of the hemispheres, the cerebral cortex, is grey matter, consisting of cortical layers of neurons. Each hemisphere is divided into four main lobes, although Terminologia Anatomica (1998) and Terminologia Neuroanatomica (2017) also include a limbic lobe and treat the insular cortex as a lobe.
The cerebrum is the largest part of the human brain, and is divided into nearly symmetrical left and right hemispheres by a deep groove, the longitudinal fissure. The outer part of the cerebrum is the cerebral cortex, made up of grey matter arranged in layers. It is 2 to 4 millimetres (0.079 to 0.157 in) thick, and deeply folded to give a convoluted appearance. Beneath the cortex is the white matter of the brain. The largest part of the cerebral cortex is the neocortex, which has six neuronal layers. The rest of the cortex is of allocortex, which has three or four layers. The hemispheres are connected by five commissures that span the longitudinal fissure, the largest of these is the corpus callosum.
HUMAN SKULL STRUCTURE
The human skull is the bony structure that forms the head in the human skeleton. It supports the structures of the face and forms a cavity for the brain. Like the skulls of other vertebrates, it protects the brain from injury.
The skull consists of two parts, of different embryological origin—the neurocranium and the facial skeleton (also called the membraneous viscerocranium). The neurocranium (or braincase) forms the protective cranial cavity that surrounds and houses the brain and brainstem. The upper areas of the cranial bones form the calvaria (skullcap). The membranous viscerocranium includes the mandible.
Except for the mandible, all of the bones of the skull are joined together by sutures—synarthrodial (immovable) joints formed by bony ossification, with Sharpey’s fibres permitting some flexibility. Sometimes there can be extra bone pieces within the suture known as wormian bones or sutural boneseg.Lambda bone.
The human skull is generally considered to consist of twenty-two bones—eight cranial bones and fourteen facial skeleton bones. In the neurocranium these are the occipital bone, two temporal bones, two parietal bones, the sphenoid, ethmoid and frontal bones.
The bones of the facial skeleton(14) are the vomer, two nasal conchae, two nasal bones, two maxilla, the mandible, two palatine bones, two zygomatic bones, and two lacrimal bones. Some sources count a paired bone as one, or the maxilla as having two bones (as its parts); some sources include the hyoid bone or the three ossicles of the middle ear but the overall general consensus of the number of bones in the human skull is the stated twenty-two.
MORE ABOUT THE DISCOVERY
“We started examining the skull very carefully, looking at it from all angles, trying to figure out how neutrophils are getting to the brain,” said Dr. Nahrendorf. “Unexpectedly, we discovered tiny channels that connected the marrow directly with the outer lining of the brain.”
Advanced imaging techniques made possible the researchers watched neutrophils moving through the channels. Blood normally flowed through the channels from the skull’s interior to the bone marrow, but after a stroke, neutrophils were seen moving in the opposite direction to get to damaged tissue.
Dr. Nahrendorf’s team detected the channels throughout the skull as well as in the tibia, which led them to search for similar features in the human skull. Detailed imaging of human skull samples obtained from surgery uncovered the presence of the channels. The channels in the human skull were five times larger in diameter compared to those found in mice. In human and mouse skulls, the channels were found in the both in the inner and outer layers of bone.
Future research will seek to identify the other types of cells that travel through the newly discovered tunnels and the role these structures play in health and disease.But this is quite enough to get most out of cell structure residing in our skull bone and brain.
SOURCE – sciencedaily