由产后上皮原生细胞启动的功能性胸腺的形成

Stem cells are undifferentiated cells that divide and produce more stem cells or progenitor cells that differentiate into mature, specialized cell types. All the cells in the body are generated from stem cells in the early embryo, but small populations of stem cells are also present in many adult tissues including the bone marrow, brain, skin, and gut. These adult stem cells typically produce the various cell types found in that tissue—to replace cells that are damaged or to continuously renew...

De novo myogenesis, or the formation of muscle fibers, begins during the early embryonic stages. The skeletal muscle is formed from somites– blocks of embryonic cell layers. The somites are further divided into dermatomes, myotomes, sclerotomes, and syndetomes. Among these, the myotomes give rise to muscle fibers.
Muscle progenitor cells (MPCs) are formed from the myotomes. MPCs express genes that encode the transcription factors Pax3 and Pax7. Along with Pax 3/7, other transcription factors...

The development of all multicellular organisms starts with the fusion of haploid cells called sperm and egg to form a diploid zygote. A zygote is a totipotent cell that can develop into a complete organism. The zygote undergoes cell division or cleavage to form an 8-cell mass. Until this stage, the cells are spherical, loosely attached, and remain totipotent. Totipotent cells are capable of developing both the embryonic and the extraembryonic tissues. However, as they continue to divide, they...

The skin is divided into epidermis, dermis, and hypodermis, the skin's outermost, middle, and inner layers. The human epidermal layer regularly undergoes renewal, where old, dead cells are replaced by new cells. Epidermal stem cells or EpiSCs divide and differentiate to restore the lost cells. For the renewal process, some EpiSCs continuously self-renew. In contrast, few others differentiate into transit-amplifying cells, which later form prickle or spinous cells, followed by granular cells,...

A hair follicle or HF is a small part of the skin that produces the hair shaft. Paul Gerson Unna was the first to observe a bulge in the human hair follicle's outer root sheath (ORS). The bulge is present between the sebaceous gland and the arrector pili muscle and is the niche for hair follicle stem cells (HFSCs). The bulge is also a niche for melanocyte stem cells, and their loss results in graying of hair. The HFSCs express Sox9 and Lhx2, which help them maintain stemness and prevent...

The liver is an important organ in vertebrates that plays an essential role in metabolism. It is also responsible for storing and redistributing nutrients such as carbohydrates, fats, and vitamins in the body. Additionally, the liver releases bile salts which are critical for digesting food and eliminating toxic metabolites from the body.
Cells of Liver
The liver comprises four major types of cells— hepatocytes, stellate, Kupffer, and sinusoidal endothelial cells. The hepatocytes are large...