Intrinsic Iron May Have Promoted Ancient Nervous Tissue Fossilization

In the CNS, neurogenesis, the birth of new neurons from stem cells, is limited to the hippocampus in adults. In other regions of the brain and spinal cord, neurogenesis is almost non-existent due to inhibitory influences from neuroglia, especially oligodendrocytes, and the absence of growth-stimulating cues. The myelin produced by oligodendrocytes in the CNS inhibits neuronal regeneration. Furthermore, astrocytes proliferate rapidly after neuronal damage, forming scar tissue that physically...

Necrosis is considered as an “accidental” or unexpected form of cell death that ends in cell lysis. The first noticeable mention of “necrosis” was in 1859 when Rudolf Virchow used this term to describe advanced tissue breakdown in his compilation titled “Cell Pathology”.
Morphological Manifestations of Necrosis
Necrotic cells show different types of morphological appearance depending on the type of tissue and infection. In coagulative necrosis, cells become...

The fossil record documents only a small fraction of all organisms that have ever inhabited Earth. Fossilization is a rare process, and most organisms never become fossils. Moreover, the fossil record only exhibits fossils that have been discovered. Nevertheless, sedimentary rock fossils of long-lived, abundant, hard-bodied organisms dominate the fossil record. These fossils offer valuable information, such as an organism's physical form, behavior, and age. Studying the fossil record helps...

Essential proteins such as insulin or low-density lipoprotein (LDL) and micronutrients such as iron enter a eukaryotic cell through receptor-mediated endocytosis. Subsequently, the early endosomes fuse with the vesicles containing such receptor-ligand complexes and play a vital role in sorting the incoming ligands and receptors. While the ligands are either degraded inside the vesicle or released into the cytosol, their receptors are returned to the plasma membrane for further rounds of...

Glia, or neuroglia, are vital support cells that assist neurons in their functions. The term "glia" originates from the Greek word for "glue," reflecting their role in holding the nervous system together. These cells can be categorized into six types: four in the central nervous system (CNS) and two in the peripheral nervous system (PNS).
The CNS glial cell includes the astrocytes, the oligodendrocytes, the microglia, and the ependymal cells.
Astrocytes are star-shaped glial...

Bones are dynamic organs that require a rich supply of oxygen and nutrients. Around 5% to 10% of the cardiac output supplies blood to the bones. A typical long bone has three main sources: the nutrient artery, the metaphyseal and epiphyseal arteries, and the periosteal arteries.
Nutrient Artery
The nutrient artery is the main blood vessel that enters the diaphysis via the nutrient foramen. While most long bones have only one nutrient foramen, large bones, such as the femur, may have two. This...