Endoderm, (sometimes called
Entoderm) is one of the
germ layerA germ layer is a group of cells, formed during animal embryogenesis. Germ layers are particularly pronounced in the vertebrates; however, all animals more complex than sponges produce two or three primary tissue layers...
s formed during animal
embryogenesisEmbryogenesis is the process by which the embryo is formed and develops. It starts with the fertilization of the ovum which, after fertilization, is referred to as a zygote. The zygote undergoes rapid mitotic divisions with no significant growth and cellular differentiation, leading to...
. Cells migrating inward along the
archenteronThe primitive gut that forms during gastrulation in the developing blastula is known as the archenteron. It develops into the digestive tract of an animal.-Formation of the Archenteron:[See Gastrulation]...
form the inner layer of the gastrula, which develops into the endoderm.
The endoderm consists at first of flattened cells, which subsequently become columnar. It forms the epithelial lining of the entire alimentary canal except part of the
mouthThe mouth, buccal cavity, or oral cavity is the first portion of the alimentary canal that receives food and begins digestion by mechanically breaking up the solid food particles into smaller pieces and mixing them with saliva...
,
pharynxThe pharynx is the part of the neck and throat situated immediately posterior to the mouth and nasal cavity, and cranial, or superior, to the esophagus, larynx, and trachea.-Functions:...
and the terminal part of the
rectumThe rectum is the final straight portion of the large intestine in some mammals, and the gut in others, terminating in the anus. The human rectum is about 12 cm long...
(which are lined by involutions of the
ectodermThe ectoderm is the start of a tissue that covers the body surfaces. It emerges first and forms from the outermost of the germ layers.Generally speaking, the ectoderm differentiates to form the nervous system, and the epidermis .In vertebrates, the ectoderm has three parts: external ectoderm , the ...
), the lining cells of all the glands which open into the digestive tube, including those of the
liverThe liver is a vital organ present in vertebrates and some other animals; it has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
and
pancreasThe pancreas is a gland organ in the digestive and endocrine system of vertebrates. It is both an endocrine gland producing several important hormones, including insulin, glucagon, and somatostatin, as well as an exocrine gland, secreting pancreatic juice containing digestive enzymes that pass to...
, the
epitheliumIn biology and medicine, an epithelium is a tissue composed of cells that line the cavities and surfaces of structures throughout the body. Many glands are also formed from epithelial tissue...
of the auditory tube and
tympanic cavityThe tympanic cavity is a small cavity surrounding the bones of the middle ear.It is formed from the tubotympanic sulcus, an expansion of the first pharyngeal pouch....
, of the
tracheaThe trachea, or windpipe, is a tube that connects to the pharynx or larynx, allowing the passage of air to the lungs. It is lined with pseudostratified ciliated columnar epithelium cells with mucosal goblet cells which produce mucus...
, bronchi, and alveoli of the lungs, of the
urinary bladderIn anatomy, the urinary bladder is the organ that collects urine excreted by the kidneys prior to disposal by urination. A hollow muscular, and distensible organ, the bladder sits on the pelvic floor...
and part of the
urethraIn anatomy, the urethra is a tube which connects the urinary bladder to the outside of the body. The urethra has an excretory function in both sexes to pass urine to the outside, and also a reproductive function in the male, as a passage for semen.The external urethral sphincter is a striated...
, and that which lines the follicles of the thyroid gland and
thymusIn human anatomy, the thymus is an organ located in the upper anterior portion of the chest cavity just behind the sternum. The main function of the thymus is to provide an area for T lymphocyte maturation, and is vital in protecting against autoimmunity....
.
Production
The following chart shows the products produced by the endoderm.
| Germ Layer | Category | Product |
|---|
| Endoderm |
General |
Gastrointestinal tractThe human gastrointestinal tract , digestive tract, guts or gut is the system of organs within humans that takes in food, digests it to extract energy and nutrients, and expels the remaining matter...
|
| Endoderm |
General |
Respiratory tract In humans the respiratory tract is the part of the anatomy that has to do with the process of respiration.The respiratory tract is divided into 3 segments:*Upper respiratory tract: nose and nasal passages, paranasal sinuses, and throat or pharynx...
|
| Endoderm |
General |
Endocrine glands and organs (liverThe liver is a vital organ present in vertebrates and some other animals; it has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
and pancreasThe pancreas is a gland organ in the digestive and endocrine system of vertebrates. It is both an endocrine gland producing several important hormones, including insulin, glucagon, and somatostatin, as well as an exocrine gland, secreting pancreatic juice containing digestive enzymes that pass to...
) |
The Endoderm has differentiated into distinguishable organs as early as 5 weeks of embryonic development.
See also
- Ectoderm
The ectoderm is the start of a tissue that covers the body surfaces. It emerges first and forms from the outermost of the germ layers.Generally speaking, the ectoderm differentiates to form the nervous system, and the epidermis .In vertebrates, the ectoderm has three parts: external ectoderm , the ...
- Germ layer
A germ layer is a group of cells, formed during animal embryogenesis. Germ layers are particularly pronounced in the vertebrates; however, all animals more complex than sponges produce two or three primary tissue layers...
- Histogenesis
Histogenesis is the formation of different tissues from undifferentiated cells. These cells are constituents of three primary germ layers, the endoderm, mesoderm, and ectoderm...
- Mesoderm
In humans, the mesoderm is one of the three primary germ cell layers - the other two are the ectoderm and endoderm - in the very early embryo. The mesoderm is the middle layer. It differentiates to gives rise to a number of tissues and structures including bone, muscle, connective tissue, and the...
- Organogenesis
In animal development, organogenesis is the process by which the ectoderm, endoderm, and mesoderm develop into the internal organs of the organism. Internal organs initiate development in humans within the 3rd to 8th weeks in utero...
- Endodermal sinus tumor
Endodermal sinus tumor , also known as yolk sac tumor , is a member of the germ cell tumor group of cancers. It is the most common testicular tumor in children under 3, and is also known as infantile embryonal carcinoma. This age group has a very good prognosis...