Vasculature in the context of "Bone marrow"

Intracranial pressure (ICP) is the pressure exerted by fluids such as cerebrospinal fluid (CSF) inside the skull and on the brain tissue. ICP is measured in millimeters of mercury (mmHg) and at rest, is normally 7–15 mmHg for a supine adult. This equals to 9–20 cmH₂O, which is a common scale used in lumbar punctures. The body has various mechanisms by which it keeps the ICP stable, with CSF pressures varying by about 1 mmHg in normal adults through shifts in production and absorption of CSF.

Changes in ICP are attributed to volume changes in one or more of the constituents contained in the cranium. CSF pressure has been shown to be influenced by abrupt changes in intrathoracic pressure during coughing (which is induced by contraction of the diaphragm and abdominal wall muscles, the latter of which also increases intra-abdominal pressure), the valsalva maneuver, and communication with the vasculature (venous and arterial systems).

Ex vivo (Latin for 'out of the living') refers to biological studies involving tissues, organs, or cells maintained outside their native organism under controlled laboratory conditions. By carefully managing factors such as temperature, oxygenation, nutrient delivery, and perfusing a nutrient solution through the tissue's vasculature, researchers sustain function long enough to conduct experiments that would be difficult or unethical in a living body. Ex vivo models occupy a middle ground between in vitro (lit. 'in the glass') models, which typically use isolated cells, and in vivo (lit. 'in the living') studies conducted inside living organisms.

Ex vivo platforms support pharmacologic screening, toxicology testing, transplant evaluation, developmental biology, and investigations of disease-mechanism research across medicine and biology, from cardiology and neuroscience to dermatology and orthopedics. Because they often use human tissues obtained from clinical procedures or biobanks, they can reduce reliance on live-animal experimentation; their utility, however, is limited by finite viability, incomplete systemic integration, and post-mortem biochemical changes that accumulate over time. The earliest perfusion studies were conducted in the mid-19th century, and subsequent advances in sterilization, imaging, and microfluidics have facilitated broader adoption into the 20th and 21st centuries. Regulatory oversight depends on specimen origin: human ex vivo research is subject to informed consent, whereas animal-derived models fall under institutional animal care guidelines.

The pharyngeal arches, also known as visceral arches, are transient structures seen in the embryonic development of humans and other vertebrates, that are recognisable precursors for many structures. In fish, the arches support the gills and are known as the branchial arches, or gill arches.

In the human embryo, the arches are first seen during the fourth week of development. They appear as a series of outpouchings of mesoderm on both sides of the developing pharynx. The vasculature of the pharyngeal arches are the aortic arches that arise from the aortic sac.