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Epithelium or epithelial tissue is a thin, continuous, protective layer of cells with little extracellular matrix. An example is the epidermis , the outermost layer of the skin . Epithelial ( mesothelial ) tissues line the outer surfaces of many internal organs , the corresponding inner surfaces of body cavities , and the inner surfaces of ...
In biology, tissue is an assembly of similar cells and their extracellular matrix from the same embryonic origin that together carry out a specific function. [1] [2] Tissues occupy a biological organizational level between cells and a complete organ. Accordingly, organs are formed by the functional grouping together of multiple tissues. [3]
by origin; This is a list of cells in humans derived from the three embryonic germ layers – ectoderm, mesoderm, and endoderm. ... Mesoderm embryonic tissues ...
It emerges and originates from the outer layer of germ cells. The word ectoderm comes from the Greek ektos meaning "outside", and derma meaning "skin". [2] Generally speaking, the ectoderm differentiates to form epithelial and neural tissues (spinal cord, nerves and brain).
Epithelial tissue is composed of closely packed cells, bound to each other by cell adhesion molecules, with little intercellular space. Epithelial cells can be squamous (flat), cuboidal or columnar and rest on a basal lamina , the upper layer of the basement membrane , [ 17 ] the lower layer is the reticular lamina lying next to the connective ...
Histogenesis is the formation of different tissues from undifferentiated cells. [1] These cells are constituents of three primary germ layers, the endoderm, mesoderm, and ectoderm. The science of the microscopic structures of the tissues formed within histogenesis is termed histology.
The mesothelium is a membrane composed of simple squamous epithelial cells of mesodermal origin, [2] which forms the lining of several body cavities: the pleura (pleural cavity around the lungs), peritoneum (abdominopelvic cavity including the mesentery, omenta, falciform ligament and the perimetrium) and pericardium (around the heart).
In all vertebrates, these progenitor cells differentiate into all adult tissues and organs. [5] In the human embryo, after about three days, the zygote forms a solid mass of cells by mitotic division, called a morula. This then changes to a blastocyst, consisting of an outer layer called a trophoblast, and an inner cell mass called the embryoblast.