Sweet secret of the multicellular life

The concept of a cell started with microscopic observations of dead cork tissue by Robert Hooke in 1665. Hooke coined the term "cell" based on the resemblance of the small subdivisions in the cork to the rooms that monks inhabited, called cells. About ten years later, Antonie van Leeuwenhoek became the first person to observe the living and moving cells under a microscope. In the century that followed, the theory that cells represented the basic unit of life developed.
Multicellular organisms...

Exocrine glands are classified as unicellular and multicellular. The unicellular glands are scattered single cells, such as goblet cells, found in the mucous membranes of the small and large intestines. On the other hand, multicellular exocrine glands develop as secretory sheets, like the internal lining of the abdomen or chest. Such secretory sheets release their secretions directly into the lumen of these organs. In addition, some multicellular glands have deep-seated secretory units to...

The origin of life on Earth is a complex and enigmatic event rooted in ancient biochemical processes and geological conditions. Experimental evidence supports the hypothesis that life began with the spontaneous formation of organic molecules such as RNA nucleotides, amino acids, and lipids under early Earth conditions. Factors like volcanic activity, intense UV radiation, and a reducing atmosphere without free oxygen likely facilitated these reactions. Hydrothermal vents on the ocean floor are...

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...

Bacterial and archaeal cells exhibit remarkable diversity in shape and structure, critical in their adaptability and functionality. Among bacteria, the most commonly observed shapes include cocci and bacilli. Cocci are spherical and may exist singly or in groupings such as pairs (diplococci), chains (streptococci), clusters (staphylococci), or tetrads. Bacilli, in contrast, are rod-shaped and can also occur as single cells, in pairs, or chains, depending on their environmental and genetic...

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...