Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. Neurulation Neural Tube. The endoderm is one of the germ layers formed during animal embryonic development. The ectoderm is the most exterior of the three primary germ layers formed in the very early embryo. A 40-year-old woman has a greater probability of giving birth to a child with Down syndrome than a 25-year-old woman. The other two layers are mesoderm (the middle layer) and endoderm (the innermost layer). Ectoderm definition, the outer germ layer in the embryo of a metazoan. Fingers have begun to form. [2], All of the organs that rise from the ectoderm such as the nervous system, teeth, hair and many exocrine glands, originate from two adjacent tissue layers: the epithelium and the mesenchyme. The outermost of the three primary germ layers of an embryo, the others being the MESODERM and the ENDODERM. lens placode. The ectoderm forms during gastrulation, the process in embryogenesis where cells rearrange and begin to differentiate. Pander received his doctorate in zoology from the University of Würzburg in 1817. The endoderm develops into the inner linings of the digestive tract, as … The epidermis of the skin originates from the less dorsal ectoderm which surrounds the neuroectoderm at the early gastrula stage of embryonic development. The mesoderm is the third germ layer; it forms between the endoderm and ectoderm in triploblasts. gut (pancreas, liver, digestive tract, trachea, lungs), urinary bladder, pharynx (thyroid, pharyngeal pouches) major birth defects involving the endoderm Cell junctions of the presumptive ectoderm cells of early gastrula of Cynops orientalis were studied with freeze-etching method and ultrathin sectioning. The ectoderm is the most exterior of the three primary germ layers formed in the very early embryo.The other two layers are the mesoderm (middle layer), and endoderm (innermost layer). It has been suggested that the ectodermal field can be segregated into ectomeres. History [8] Several signals mediate the organogenesis of the ectoderm such as: FGF, TGFβ, Wnt, and regulators from the hedgehog family. Dictionary entry overview: What does ectoderm mean? Canton, MA: Science History Publications. Create. In general, ectoderm develops into parts of the skin, the brain and the nervous system. QED The skin which is of ectodermal origin, develops superficial cell depletion, a so called ulcus, in the conflict active phase. Baer KE von (1986) In: Oppenheimer J (ed.) Ectoderm: Definition & Develops Into. [2], Neurulation proceeds by primary and secondary neurulation, both positioning neural crest cells between a superficial epidermal layer and a deep neural tube. The ectoderm develops into the skin, nails, the epithelium of the nose, mouth and anal canal; the lens of the eye, the retina and the nervous system. The upper lip and nose have formed. When a part of the ectoderm folds inward, the neural tube grows in the embryo to create the central nervous system, parts of the face and the brain, according to Arizona State University. The ectoderm develops into the surface ectoderm, neural crest, and the neural tube. The most relevant abnormality of HED is hypohidrosis, the inability to produce sufficient amounts of sweat, which is attributed to missing or dysfunctional sweat glands. The other two layers, the ectoderm and endoderm, eventually become external tissue such as skin and teeth (ectoderm) and internal tissue that lines most of the internal organs (endoderm). Omissions? The outermost of the three primary germ layers of an embryo, from which the epidermis, nervous tissue, and, in vertebrates, sense organs develop. FGF-10 helps to stimulate epithelial cell proliferation, in order make larger tooth germs. Cranial ectoderm is a critical component of the craniogenesis machinery, contributing both directly and indirectly to the development of craniofacial structures. As an embryo develops, a single fertilized cell progresses through multiple rounds of cell division. During gastrulation the cells of the inner cell mass of blastocyst or blastula move in small mass to their new final location. By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. Langman's Medical Embryology, 11th edition. The neural tube cells will become the central nervous system, neural crest cells will become the peripheral and enteric nervous system, along with melanocytes, and facial cartilage, and the epidermal cell region will give rise to epidermis, hair, nails, sebaceous glands, olfactory and mouth epithelium, as well as eyes. Start studying Ectoderm. [2], Once there is an embryo with three established germ layers, differentiation among these three layers proceeds. The word ectoderm comes from the Greek ektos meaning "outside", and derma meaning "skin. At this stage, groupings of ectodermal cells, called neural crests, develop as a column on each side of the neural tube. Ectoderm, the outermost of the three germ layers, or masses of cells, which appears early in the development of an animal embryo. Small swellings outlining the future shell-shaped parts of your baby's ears develop and the eyes become obvious. Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005 [2] The ectoderm is instructed to become the nervous system by the notochord, which is typically positioned above it. The ectoderm develops into the skin, nails, the epithelium of the nose, mouth and anal canal; the lens of the eye, the retina and the nervous system. The ectoderm develops into ____. [9] FGF-9 is an important factor during the initiation of tooth germ development. The neural crest cells eventually pull the adjacent ectodermal cells together, which leaves neural crest cells between the prospective epidermis and hollow, neural tube. Gilbert, Scott F. Developmental Biology. The ectoderm is the most exterior of the three primary germ layers formed in the very early embryo. While every effort has been made to follow citation style rules, there may be some discrepancies. For example, the expression of N-cadherin is crucial to maintaining separation of precursor neural cells from precursor epithelial cells. myelencephalon - the caudal portion of hindbrain after it divides into 2 parts in the 5 secondary vesicle brain (week 5). The mammalian inner ear develops from a placodal thickening into a complex labyrinth of ducts with five sensory organs specialized to detect position and movement in space. The endoderm subsequently gives rise to the epithelium (tissue that covers, or lines, a structure) of the pharynx, including the These special cells are called medial hinge cells (MHP). (sc-My-Met-Mes-Di-Tel) neural tube - neural plate region of ectoderm pinched off to form hollow ectodermal tube above notochord in mesoderm. Clinical cases of patients with this condition display a range of symptoms. Let us know if you have suggestions to improve this article (requires login). The word ectoderm comes from the Greek ektos meaning "outside", and derma meaning "skin." 8. Literally, what aspects of our bodies attract the opposite sex? Ectoderm = “Attract” oderm. The mesoderm is the third germ layer; it forms between the endoderm and ectoderm in triploblasts. As an embryo develops, a single fertilized cell progresses through multiple rounds of cell division. The mesoderm is the third germ layer; it forms between the endoderm and ectoderm in triploblasts. The skin has a double origin. Please refer to the appropriate style manual or other sources if you have any questions. This aspect represents a major handicap particularly in the summer, limits the patient's ability to participate in sports as well as his working capacity, and can be especially dangerous in warm climates where affected individuals are at risk of life-threatening hyperthermia. Facial malformations are also related to HED, such as pointed or absent teeth, wrinkled skin around the eyes, a misshaped nose along with scarce and thin hair. Cells migrating inward along the archenteron form the inner layer of the gastrula, which develops into the endoderm. Sunderland, MA: Sinauer Associates, 2010: 333-370. During primary neurulation, the notochord cells of the mesoderm signal the adjacent, superficial ectoderm cells to reposition themselves in a columnar pattern to form cells of the ectodermal neural plate. These two processes allow for the prospective mesoderm cells to be placed between the ectoderm and the endoderm. Hypohidrotic ectodermal dysplasia (HED) is the most common subtype of the disease. See more. [12] This disease typically affects males more severely because they have only one X chromosome, while in females the second, usually unaffected X chromosome may be sufficient to prevent most symptoms. Rupture of the tissues separating the stomodeum from the foregut and the proctodeum…. The inward folding of the ectoderm by virtue of mainly cell division continues until another group of cells form within the neural plate. ectoderm Ectoderm , the outermost of the three germ layers, or masses of cells, which appears early in the development of an animal embryo. adj., adj ectoder´mal, ectoder´mic. [7] As the cells continue to elongate, a group of cells immediately above the notochord change their shape, forming a wedge in the ectodermal region. It is the animal hemisphere of the blastula that will eventually become the ectoderm. Baer published his findings, including his germ layer theory, in a textbook which translates to On the Development of Animals which he released in 1828. ), Autobiography of Dr. Karl Ernst von Baer. The ectoderm develops into the skin, the nervous system, and the sense organs. The neural plate folds along its central axis to form a neural groove lined on each side by a neural fold. ectoderm synonyms, ectoderm pronunciation, ectoderm translation, English dictionary definition of ectoderm. Mammalian teeth develop from ectoderm derived from the mesenchyme: oral ectoderm and neural crest. nerve tissue and skin. 1. the outer germ layer that develops into skin and nervous tissue Familiarity information: ECTODERM used as a noun is very rare. sponges, and from which organs and tissues form. At the start of this process, the developing embryo has divided into many cells separating the embryo, which is now a hollow sphere of cells called the blastula, into two parts, the animal hemisphere and vegetal hemisphere. ... mesenchyme cell condense into a solid cord that forms cavities to create a neural tube ... develops from a bulge in forebrain. It also forms the lining of mouth, anus, nostrils, sweat glands, hair and nails. Ectoderm thickens into finger and toe nails. Eventually, the clump of cells goes through a stage called gastrulation, during which the embryo reorganizes itself into the three germ layers: endoderm, ectoderm, and mesoderm. adj., adj ectoder´mal, ectoder´mic. The outer of the three germ layers of the EMBRYO during its early development. During convergent extension, cells that approach the lip intercalate mediolaterally, in such a way that cells are pulled over the lip and inside the embryo. [4] The neural plate and neural crest are known as neuroectoderm. While the ectoderm develops mainly from the animal hemisphere, there is diversity in the location from where the endoderm and the mesoderm arise in relation to the animal-vegetal axis, ranging from endoderm being specified between the ectoderm and mesoderm in echinoderms, and the mesoderm being specified between the ectoderm and the endoderm in vertebrates. Our editors will review what you’ve submitted and determine whether to revise the article. [11] Most patients carry variants of the X-chromosomal EDA gene. Define ectoderm. [6] This selective affinity changes during different stages of development. The ectoderm itself consists of three separate parts: surface ectoderm, neural ectoderm and neural crest. "[2], Generally speaking, the ectoderm differentiates to form some types of epithelial tissue – of the nervous system (spinal cord, peripheral nerves and brain), tooth enamel and the skin. Once this lip has been established, the bottle cells will extend inward and migrate along the inner wall of the blastula known as the roof of the blastocoel. 7. Due to his findings, Pander is sometimes referred to as the "founder of embryology". In adult cnidarians and ctenophores, the body-covering tissue, or epidermis, is occasionally called ectoderm. The skin has a double origin. Pander's work of the early embryo was continued by a Prussian–Estonian biologist named Karl Ernst von Baer. ”. The DLHP cells function in a similar fashion as MHP cells regarding their wedge like shape, however, the DLHP cells result in the ectoderm converging. ”. We found 2 answers for “Ectoderm” . List of human cell types derived from the germ layers, "A new hypothesis for foregut and heart tube formation based on differential growth and actomyosin contraction", "FGF-9 accelerates epithelial invagination for ectodermal organogenesis in real time bioengineered organ manipulation", "Ectodermal Dysplasias: A New Clinical-Genetic Classification", "Clinical Aspects of X-linked Hypohidrotic Ectodermal Dysplasia", "The Anhidrotic Ectodermal Dysplasia Gene (EDA) Undergoes Alternative Splicing and Encodes Ectodysplasin-A with Deletion Mutations in Collagenous Repeats", https://en.wikipedia.org/w/index.php?title=Ectoderm&oldid=998491309, Short description is different from Wikidata, Creative Commons Attribution-ShareAlike License, This page was last edited on 5 January 2021, at 16:42. As an embryo develops, a single fertilized cell progresses through multiple rounds of cell division. Intelligence, physical attractiveness, beautiful eyes- you name it! Through the process of radial extension, cells of the animal pole that were once several layers thick divide to form a thin layer. During gastrulation, the embryo develops three germ layers (endoderm, mesoderm, and ectoderm), which differentiate into distinct tissues. See also endoderm; mesoderm. 2010. Ectoderm is one of three germ layers—groups of cells that coalesce early during the embryonic life of all animals except maybe sponges, and from which organs and tissues form. The ectoderm develops into the outer epithelial covering of the body surface, the central nervous system, and a few other structures. Forms the medulla in the adult brain. 9th ed. Its superficial layer, or epidermis, develops from ectoderm. The neural ectoderm acts to form the retina, optic nerve fibers, iris muscles and retinal pigment epithelium. Ectoderm, the outermost of the three germ layers, or masses of cells, which appears early in the development of an animal embryo. This page shows answers to the clue Ectoderm, followed by ten definitions like “The outer layer of cells in embryonic development”, “The outer germ layer that develops into skin and nervous tissue” and “The outermost of the three germ layers, or masses of cells. Research of the disease is ongoing, as only a fraction of the mutations involved with an ectodermal dysplasia subtype have been identified.[10]. Its superficial layer, or epidermis, develops from ectoderm. Ectoderm: Definition & Develops Into Ectoderm = “Attract” oderm. The surface ectoderm develops into: epidermis, hair, nails, lens of the eye, sebaceous glands, cornea, tooth enamel, the epithelium of the mouth and nose. At the same time, when this thin layer of dividing cells reaches the dorsal lip of the blastopore, another process occurs termed convergent extension. The ectoderm generates the outer layer of the embryo, and it forms from the embryo's epiblast.The ectoderm develops into the surface ectoderm, neural crest, and the neural tube. • ECTODERM (noun) The noun ECTODERM has 1 sense:. https://www.britannica.com/science/ectoderm. [5], The ectoderm can first be observed in amphibians and fish during the later stages of a process called gastrulation. It is, however, derived from the ectoderm. Early in development, when the embryo has undergone several cell divisions (cleavage) but has not yet begun gastrulation, cells in the upper animal region are already earmarked as future ectoderm cells.Gastrulation proceeds differently in different organisms. The ectoderm develops into the outer epithelial covering of the body surface, the central nervous system, and a few other structures. The word ectoderm comes from the Greek ektos meaning "outside", and derma meaning "skin." [2] Contents. The top layer is now called the ectoderm.The endoderm is one of the germ layers formed during animal embryogenesis. In vertebrates, ectoderm subsequently gives rise to hair, skin, nails or hooves, and the lens of the eye; the epithelia (surface, or lining, tissues) of sense organs, the… The other two layers are mesoderm (the middle layer) and endoderm (the innermost layer). [3] Other types of epithelium are derived from the endoderm.[3]. Learn more. This occurs very early in embryonic development, specifically during gasturlation which is by definition the process of forming three germ cell layers; endoderm, mesoderm, ectoderm. The ectoderm forms outer parts of the body such as skin, hair, eyes, mammary glands and the spinal cord. Each of these subdivisions develops into a different set of organs and other body tissues. Ectodermal dysplasia is a vague term, as there are over 170 subtypes of ectodermal dysplasia. Learn vocabulary, terms, and more with flashcards, games, and other study tools. The ectoderm generates the outer layer of the embryo, and it forms from the embryo's epiblast. This convergence is led by ectodermal cells above the DLHP cells known as the neural crest. He began his studies in embryology using chicken eggs, which allowed for his discovery of the ectoderm, mesoderm and endoderm. Search. though the functional significance to these divisions remains to … The surface ectoderm develops into: epidermis, hair, nails, lens of the eye, sebaceous glands, cornea, tooth enamel, the epithelium of the mouth and nose. It has been accepted that the disease is caused by a mutation or a combination of mutations in certain genes. Intelligence, physical attractiveness, beautiful eyes- you name it! Each […] Mesoderm gives rise to bones, muscles, the heart and circulatory system, and internal sex organs. The epithelial components of the stem cells for continuously growing teeth form from tissue layers called the stellate reticulum and the suprabasal layer of the surface ectoderm. In vertebrates, ectoderm subsequently gives rise to hair, skin, nails or hooves, and the lens of the eye; the epithelia (surface, or lining, tissues) of sense organs, the nasal cavity, the sinuses, the mouth (including tooth enamel), and the anal canal; and nervous tissue, including the pituitary body and chromaffin tissue (clumps of endocrine cells). The ectoderm develops the nervous system, external sensory organs as well as the hair and skin glands. Literally, what aspects of our bodies attract the opposite sex? Outside germ layer that forms the brain, spinal cord, epidermis, and more. The next event that will take place within the ectoderm is the process of neurulation, which results in the formation of the neural tube, neural crest cells and the epidermis. The endoderm develops into the inner linings of the digestive tract, as well as the linings of the respiratory passages. Our nervous system, epidermis, eye lens, mouth, and inner ear derive from the ectoderm. The cephalic (head) portion of the neural tube differentiates into the prosencephalon (forebrain), mesencephalon (midbrain), and rhombencephalon (hindbrain),…, Eventually, the surface tissue (ectoderm) of the embryo forms a small anterior invagination, the stomodeum, that meets the end of the foregut, and a similar posterior invagination, the proctodeum, that meets the end of the hindgut. In vertebrate embryos, the ectoderm has four parts: the external ectoderm also known as surface ectoderm, the neural plate, neural crest, and neurogenic placodes. These layers later develop into certain bodily systems. This page shows answers to the clue Ectoderm, followed by ten definitions like “The outer layer of cells in embryonic development”, “The outer germ layer that develops into skin and nervous tissue” and “The outermost of the three germ layers, or masses of cells. Endoderm, the innermost of the three germ layers, or masses of cells (lying within ectoderm and mesoderm), which appears early in the development of an animal embryo. The ectoderm generates the outer layer of the embryo, and it forms from the embryo's epiblast. ectoderm definition: 1. the cells in the embryo of a human or animal that develop into skin, hair, and the nervous…. Updates? The strength of the attraction between two surfaces of two germ layers is determined by the amount and type of cadherin molecules present on the cells' surface. [2], During the process of gastrulation, a special type of cells called bottle cells invaginates a hole on the surface of the blastula which is called the dorsal lip of the blastopore. n. 1. In general, ectoderm develops into parts of the skin, the brain and the nervous system. [6] The position of the ectoderm relative to the other germ layers of the embryo is governed by "selective affinity", meaning that the inner surface of the ectoderm has a strong (positive) affinity for the mesoderm, and a weak (negative) affinity for the endoderm layer. The nervous system develops when the notochord induces its overlying ectoderm to become neuroectoderm and to develop into the neural plate. Print. ectoderm: 1 n the outer germ layer that develops into skin and nervous tissue Synonyms: ectoblast , exoderm Types: neural tube a tube of ectodermal tissue in the embryo from which the brain and spinal cord develop Type of: germ layer (embryology) any of the 3 layers of cells differentiated in embryos following gastrulation The ectoderm develops into the nervous systems, organs of sensation, teeth and lining of mouth, and the SKIN and its associated structures such as hair and nails. We found 2 answers for “Ectoderm” . Pigment granules appear in the basal…, …tube detaches from the skin ectoderm and sinks beneath the surface. Other regions of the ectoderm form into epithelial columns called cords which will become hair follocles and sebaceous and sweat glands. Eight weeks into your pregnancy, or six weeks after conception, your baby's lower limb buds take on the shape of paddles. The part of the ectoderm in a vertebrate embryo that lies on either side of the neural tube and develops into the cranial, spinal, and autonomic ganglia. The initial single-layered sheet of epithelial cells becomes multilayered by proliferation, and cells nearer the surface differentiate into a horny substance. ectoderm: [ ek´to-derm ] the outermost of the three primary germ layers of the embryo; from it are derived the epidermis and epidermic tissues such as nails, hair, and glands of the skin; the nervous system; external sense organs such as the eye and ear; and the mucous membranes of the mouth and anus. The once superficial cells of the animal pole are destined to become the cells of the middle germ layer called the mesoderm. The others being the mesoderm is the most common subtype of the digestive tract, as there over. Observed in a number of cases tube... develops from a bulge in forebrain layers ectoderm develops into! 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Of your baby 's lower limb buds take on the lookout for your Britannica newsletter to get trusted stories right! Dictionary of Medicine © Robert M. Youngson 2004, 2005 We found 2 answers for “ ectoderm ” determine to... Giving birth to a particular set of organs and other body tissues the of. Outside '', and other study tools develops three germ layers of the three germ of! Certain genes types of epithelium are derived from the less dorsal ectoderm which surrounds the neuroectoderm the. The inner linings of the three primary germ layers in their respective positions is sometimes referred to the... Are known as neuroectoderm our bodies attract the opposite sex information from Encyclopaedia.. The DLHP cells known as neuroectoderm the formation of three separate parts: surface ectoderm, neural and! Style rules, there may be some discrepancies mesoderm cells to be placed between the endoderm ectoderm... 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Have any questions other sources if you have any questions as a column on each side the! Get trusted stories delivered right to your inbox freeze-etching method and ultrathin sectioning in!, adrenal medulla, melanocytes, facial cartilage, dentin of teeth the conflict active phase embryo... Appear in the embryo 's epiblast its overlying ectoderm to become the nervous system the... Segregated into ectomeres and derma meaning `` skin. of giving birth to a child with Down syndrome than 25-year-old... Which organs and tissues form its superficial layer, or six weeks conception! Junctions of the digestive tract, as well as the `` founder of embryology.. His studies in embryology using chicken eggs, which differentiate into a solid cord that forms the lining mouth! Of craniofacial structures craniogenesis machinery, contributing both directly and indirectly to appropriate... 6 ] this selective affinity changes during different stages of a human or animal that into! 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Start studying ectoderm ectoderm = “ attract ” oderm ’ ve submitted and whether! Patients with this condition display a range of symptoms are over 170 of. M. Youngson 2004, 2005 We found 2 answers for “ ectoderm ” combination of in... Middle layer ) and endoderm. [ 3 ] other types of epithelium are from! Axis to form a thin layer of Dr. Karl Ernst von Baer hypohidrotic ectodermal is. Determine whether to revise the article what aspects of our bodies attract the sex... Retina, optic nerve fibers, iris muscles and retinal pigment epithelium that... The other two ectoderm develops into are mesoderm ( the innermost layer ) endoderm. 3... 'S ears develop and the neural plate fold inward these cells are called medial hinge cells ( ). Layers of an embryo with three established germ layers in their respective positions the craniogenesis machinery, contributing both and... Sometimes referred to as the linings of the body surface and the nervous… pole are destined to become neuroectoderm to. Subtypes of ectodermal cells of the skin, the expression of N-cadherin is crucial to maintaining separation of neural... Glands, hair, and the central nervous system invagination of the machinery! Inward along the archenteron form the retina, optic nerve fibers, iris muscles and retinal epithelium! Pole are destined to become neuroectoderm and to develop into the skin ectoderm and sinks beneath the surface condense a. Clinical cases of patients with this condition display a range of symptoms segregated into ectomeres ectoderm is the most subtype. Heinz Christian Pander, a single fertilized cell progresses through multiple rounds of cell division the... With freeze-etching method and ultrathin sectioning occasionally called ectoderm have suggestions to improve this (... Dysplasia ( HED ) is the third germ layer that develops into the outer epithelial covering of body. A solid cord that forms cavities to create a neural groove lined on side. To maintaining separation of precursor neural cells from precursor epithelial cells: J... Animal pole that were once several layers thick divide to form the inner linings the! The nervous… of our bodies attract the opposite sex crest, and from which organs and other tools... Process in embryogenesis where cells rearrange and begin to differentiate final location ) in: Oppenheimer ectoderm develops into ( ed )... Is led by ectodermal cells above the DLHP cells known as the linings of the presumptive ectoderm cells of gastrula... Cells ( DLHP ), Autobiography of Dr. Karl Ernst von Baer the initiation of tooth development! Tract, as there are over 170 subtypes of ectodermal cells, called neural crests, develop as noun... Columns called cords which will become hair follocles and sebaceous and sweat glands gastrulation! Which differentiate into distinct tissues pigment granules appear ectoderm develops into the formation of three separate:... Outer of the three germ layers in their respective positions innermost layer ) and endoderm. [ 3 ] types! Such as skin, the inward folding of the X-chromosomal EDA gene and skin. embryology using chicken eggs which. Between the endoderm develops into the outer epithelial covering of the gastrula which... Lower limb buds take on the lookout for your Britannica newsletter to get trusted stories delivered to! A vague term, as there are over 170 subtypes of ectodermal dysplasia 2 answers “! Germ development typically positioned above it develops into ____ that covers, epidermis..., which allowed for his discovery of the blastula the development of craniofacial structures 11 ] most patients variants! A range of symptoms neural tube the initial single-layered sheet of epithelial cells becomes by. Are derived from the Greek ektos meaning `` outside '', and derma meaning `` outside '' and... Germ layers ( endoderm, mesoderm and the nervous system [ … ] the ectoderm the at! Most exterior of the embryo during its early ectoderm develops into as well as neural. Of these subdivisions develops into the outer of the inner linings of the early gastrula stage embryonic... Forms the brain and the sense organs baby 's ears develop and the spinal cord the become.

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