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Developmental biology lecture | embryo development

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Developmental biology lecture | embryo development

Embryo development - This developmental biology lecture explains different stages of embryonic development in details. It includes the explanation for fertilization, morula, blastula and gastrula in step by step. It also explains the neurulation in frog and chick embryo. it explains the morphogenesis pattern in drosophila development.
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Developmental biology part 1 : introduction and grey crescent formation

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Embryogenesis is the step in the life cycle after fertilisation -- the development of the embryo, starting from the zygote (fertilised egg). Organisms can differ drastically in how the embryo develops, especially when they belong to different phyla. For example, embryonal development in placental mammals starts with cleavage of the zygote into eight uncommited cells, which then form a ball (morula). The outer cells become the trophectoderm or trophoblast, which will form in combination with maternal uterine endometrial tissue the placenta, needed for fetal nurturing via maternal blood, while inner cells become the inner cell mass that will form all fetal organs (the bridge between these two parts eventually forms the umbilical cord). In contrast, the fruit fly zygote first forms a sausage-shaped syncytium, which is still one cell but with many cell nuclei.[18]

Patterning is important for determining which cells develop into which organs. This is mediated by signaling between adjacent cells by proteins on their surfaces, and by gradients of signaling secreted molecules.[19] An example is retinoic acid, which forms a gradient in the head to tail direction in animals. Retinoic acid enters cells and activates Hox genes in a concentration-dependent manner -- Hox genes differ in how much retinoic acid they require for activation and will thus show differential rostral expression boundaries, in a colinear fashion with their genomic order. As Hox genes code for transcription factors, this causes different activated combinations of both Hox and other genes in discrete anteroposterior transverse segments of the neural tube (neuromeres) and related patterns in surrounding tissues, such as branchial arches, lateral mesoderm, neural crest, skin and endoderm, in the head to tail direction.This is important for e.g. the segmentation of the spine in vertebrates.

Embryonic development does not always proceed correctly, and errors can result in birth defects or miscarriage. Often the reason is genetic (mutation or chromosome abnormality), but there can be environmental influence (like teratogens) or stochastic events. Abnormal development caused by mutation is also of evolutionary interest as it provides a mechanism for changes in body plan (see evolutionary developmental biology).

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21. Development 1

MIT 7.013 Introductory Biology, Spring 2011
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Instructor: Hazel Sive

Professor Sive discusses cell types and explains how they differentiate.

License: Creative Commons BY-NC-SA
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Developmental biology part 7 : Development of chick

This embryology lecture under the developmental biology series explains the development of chick from egg after fertilization.
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Developmental biology part 2 : clevage of zygote, polarity and differentiation

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Embryogenesis is the step in the life cycle after fertilisation -- the development of the embryo, starting from the zygote (fertilised egg). Organisms can differ drastically in how the embryo develops, especially when they belong to different phyla. For example, embryonal development in placental mammals starts with cleavage of the zygote into eight uncommited cells, which then form a ball (morula). The outer cells become the trophectoderm or trophoblast, which will form in combination with maternal uterine endometrial tissue the placenta, needed for fetal nurturing via maternal blood, while inner cells become the inner cell mass that will form all fetal organs (the bridge between these two parts eventually forms the umbilical cord). In contrast, the fruit fly zygote first forms a sausage-shaped syncytium, which is still one cell but with many cell nuclei.[18]

Patterning is important for determining which cells develop into which organs. This is mediated by signaling between adjacent cells by proteins on their surfaces, and by gradients of signaling secreted molecules.[19] An example is retinoic acid, which forms a gradient in the head to tail direction in animals. Retinoic acid enters cells and activates Hox genes in a concentration-dependent manner -- Hox genes differ in how much retinoic acid they require for activation and will thus show differential rostral expression boundaries, in a colinear fashion with their genomic order. As Hox genes code for transcription factors, this causes different activated combinations of both Hox and other genes in discrete anteroposterior transverse segments of the neural tube (neuromeres) and related patterns in surrounding tissues, such as branchial arches, lateral mesoderm, neural crest, skin and endoderm, in the head to tail direction.[20] This is important for e.g. the segmentation of the spine in vertebrates.[19]

Embryonic development does not always proceed correctly, and errors can result in birth defects or miscarriage. Often the reason is genetic (mutation or chromosome abnormality), but there can be environmental influence (like teratogens) or stochastic events.[21][22] Abnormal development caused by mutation is also of evolutionary interest as it provides a mechanism for changes in body plan (see evolutionary developmental biology).[2 Source of the article published in description is Wikipedia. I am sharing their material. Copyright by original content developers of Wikipedia.
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Introduction to Animal Development

class notes on animal development
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Development: Timing and Coordination

024 - Regulation of Timing and Coordination in Development - Paul Andersen explains how genes control the timing and coordination of embryo development. Seed germination initiates the discussion of cell differentiation. The SRY gene and genetic transplantation shows the importance of embryonic discussion. Cell deat is also an important part of development that is regulated by microRNA. HOX genes (a form of homeotic genes) is also discussed.

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All of the images are licensed under creative commons and public domain licensing:
Animal Cell Clip Art, n.d.
Benjamint444. Sunflower Seed. Whole Seed (achene) (right) and Just the Kernel with the Shell Removed (left), [object HTMLTableCellElement]. Own work.
Boisclair, Eric. VF-101 Grim Reapers Tail Art, June 29, 2008.
Chromosome, n.d.
English: Embryonic Stem Cells. (A) Shows hESCs. (B) Shows Neurons Derived from hESCs., July 12, 2005. Follow the Money -- The Politics of Embryonic Stem Cell Research. Russo E, PLoS Biology Vol. 3/7/2005, e234. doi:10.1371/journal.pbio.0030234.
Erythrocyte Red Blood Cell, n.d.
File: Sunflower Seedlings.jpg, n.d.
File:DrosophilaKutikula.jpg. Wikipedia, the Free Encyclopedia. Accessed November 23, 2013.
File:Hoxgenesoffruitfly.svg. Wikipedia, the Free Encyclopedia. Accessed November 23, 2013.
File:Human Embryo - Approximately 8 Weeks Estimated Gestational Age.jpg. Wikipedia, the Free Encyclopedia. Accessed November 23, 2013.
File:Microrna Secondary Structure.png. Wikipedia, the Free Encyclopedia. Accessed November 23, 2013.
File:Sperm-Egg.jpg. Wikipedia, the Free Encyclopedia. Accessed November 23, 2013.
Healthy Neuron Clip Art, n.d.
Mr.checker. Deutsch: Drosophila Melanogaster (Schwarzbäuchige Taufliege), July 5, 2009. Own work.
Thermometer 9 Clip Art, n.d.
USA, Ed Uthman from Houston, TX. 9-Week Human Embryo from Ectopic Pregnancy (7th Week P.o.), December 1, 1999. 9-Week Human Embryo from Ectopic Pregnancy.
User:Haplochromis. Astyanax Mexicanus, Normal Form and Blind Cave-Form, February 11, 2007. Self-photographed.
Česky: SRY Protein Navázaný Na DNA, [object HTMLTableCellElement]. transferred from en wikipedia, stated to be public domain from
Yahoo Voices - Voices.yahoo.com. Yahoo Contributor Network. Accessed November 23, 2013.
Zell, H. Deutsch: Astyanax Mexicanus, Characidae, Blinder Höhlensalmler; Staatliches Museum Für Naturkunde Karlsruhe, Deutschland., May 21, 2011. Own work.

Intro Music Atribution
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Animal Development: We're Just Tubes - Crash Course Biology #16

Hank discusses the process by which organisms grow and develop, maintaining that, in the end, we're all just tubes.

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Table of Contents
1) Zygote 2:38
2) Morula 2:53
3) Blastula 3:25
4) Radial Symmetry 4:11
5) Bilateral Symmetry 4:26
6) Gastrulation 4:52
7) Blastopore 5:02
8) Gastrula 5:17
9) Protostomes & Deuterostomes 5:33
10) Germ Layers 6:22
a) Diploblastic 6:32
b) Triploblastic 6:44
11) Biolography 7:27

References for this episode can be found in the Google document here:

animal development, biology, science, crashcourse, animal, classification, phylum, embryo, multi-cellular, sea sponge, symmetry, organs, cells, complexity, tube, life form, tissue, jellyfish, coral, sperm, egg, zygote, morula, blastula, mouth, anus, radial symmetry, bilateral symmetry, digestive tract, gastrulation, gastrula, protostome, deuterostome, chordate, vertebrate, ectoderm, endoderm, germ layer, mesoderm, ernst haeckel, recapitulation theory, ontogeny, phylogeny, evolution, embryology, developmental biology Support CrashCourse on Subbable:

Developmental biology part 5, developmental biology of drosophila

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During oogenesis, cytoplasmic bridges called ring canals connect the forming oocyte to nurse cells. Nutrients and developmental control molecules move from the nurse cells into the oocyte. In the figure to the left, the forming oocyte can be seen to be covered by follicular support cells.

After fertilization of the oocyte the early embryo (or syncytial embryo) undergoes rapid DNA replication and 13 nuclear divisions until approximately 5000 to 6000 nuclei accumulate in the unseparated cytoplasm of the embryo. By the end of the 8th division most nuclei have migrated to the surface, surrounding the yolk sac (leaving behind only a few nuclei, which will become the yolk nuclei). After the 10th division the pole cells form at the posterior end of the embryo, segregating the germ line from the syncytium. Finally, after the 13th division cell membranes slowly invaginate, dividing the syncytium into individual somatic cells. Once this process is completed gastrulation starts.[23]

Nuclear division in the early Drosophila embryo happens so quickly there are no proper checkpoints so mistakes may be made in division of the DNA. To get around this problem, the nuclei that have made a mistake detach from their centrosomes and fall into the centre of the embryo (yolk sac), which will not form part of the fly.

The gene network (transcriptional and protein interactions) governing the early development of the fruit fly embryo is one of the best understood gene networks to date, especially the patterning along the antero-posterior (AP) and dorso-ventral (DV) axes (See under morphogenesis).[23]

The embryo undergoes well-characterized morphogenetic movements during gastrulation and early development, including germ-band extension, formation of several furrows, ventral invagination of the mesoderm, posterior and anterior invagination of endoderm (gut), as well as extensive body segmentation until finally hatching from the surrounding cuticle into a 1st-instar larva.

During larval development, tissues known as imaginal discs grow inside the larva. Imaginal discs develop to form most structures of the adult body, such as the head, legs, wings, thorax and genitalia. Cells of the imaginal disks are set aside during embryogenesis and continue to grow and divide during the larval stages—unlike most other cells of the larva, which have differentiated to perform specialized functions and grow without further cell division. At metamorphosis, the larva forms a pupa, inside which the larval tissues are reabsorbed and the imaginal tissues undergo extensive morphogenetic movements to form adult structures. Source of the article published in description is Wikipedia. I am sharing their material. Copyright by original content developers of Wikipedia.
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Lecture 2 Developmental Genetics

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Early embryogenesis - Cleavage, blastulation, gastrulation, and neurulation | MCAT | Khan Academy

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Richard Harland (UC Berkeley) 1: Early Frog Development: How to Make a Tadpole



Xenopus laevis, is an excellent model to study vertebrate development. Richard Harland outlines frog development including the cell movements and molecular signals of gastrulation.

Talk Overview:
Richard Harland begins his talk by asking how a fertilized egg goes from a single cell to a complex, multicellular organism during vertebrate development.  He explains that amphibians, and in particular Xenopus laevis, are an excellent system for addressing this question.  For example, early experiments by Spemann and Mangel in newt embryos were the first to demonstrate the presence of an “organizer” region, and more recent studies in Xenopus have identified many signaling molecules that control embryogenesis. Throughout his talk, Harland shows stunning movies to illustrate the beauty and complexity of early frog development.

During the gastrulation, cell movements result in a massive reorganization of the embryo from a simple spherical ball of cells, the blastula, into a multi-layered organism. In his second video, Harland simplifies this complex phase of frog development by breaking it down into 7 separate steps and describing the specific cell rearrangements associated with each step.

In his last talk, Harland introduces the signaling molecules responsible for specifying distinct tissues in the embryo.  He explains how gradients of signaling molecules, such as β-catenin and Nodal, are initially set up in the egg and how these gradients induce the formation of the mesoderm layer. He also describes classic experiments from the 1990s showing that the organizer is necessary to pattern the mesoderm into tissues such as muscle and neural plate. Harland then focuses on experiments from his lab that identified the molecules expressed in the organizer that specify dorsal cell fate.  

Speaker Biography:
Richard Harland is the C. H. Li Distinguished Professor of Molecular and Cellular Biology at the University of California, Berkeley where his lab studies early vertebrate development in both Xenopus and in mice. As a PhD student, Harland studied DNA replication in the lab of Dr. Ron Laskey at the MRC Laboratory of Molecular Biology, Cambridge. He moved to the USA, and began his studies of vertebrate development, as a post-doc with Harold Weintraub at the Fred Hutchinson Cancer Research Center. In 1985, Harland joined the faculty at UC Berkeley.

As well as running a successful research lab, Harland is an integral member of the developmental biology community.  He has played an important role in the project to sequence the Xenopus tropicalis and X. laevis genomes. He has taught in the Marine Biological Lab Embryology course for over 15 years and he co-authored the textbook “Early Development of Xenopus laevis: A Laboratory Manual”.  His contributions to science and teaching have been recognized with the award of the E.G. Conklin Medal from the Society for Developmental Biology and election to the National Academy of Sciences.

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Gene Regulation - Embryonic Development | BIALIGY.com

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Online Developmental Biology: Overview of the Field

Unit 1, Lecture 1: Little Man.
History of the field, current concepts, and future video lecture content

Fertilization in sea urchin | Developmental biology lecture

Fertilization in sea urchin- This developmental biology lecture explains about the fertilization process in sea urchin. It also explains the polyspermy prevention in sea urchin development.
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Remember Shomu’s Biology is created to spread the knowledge of life science and biology by sharing all this free biology lectures video and animation presented by Suman Bhattacharjee in YouTube. All these tutorials are brought to you for free. Please subscribe to our channel so that we can grow together. You can check for any of the following services from Shomu’s Biology-
Buy Shomu’s Biology lecture DVD set-
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Cleavage and Blastulation

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Introduction to Embryological Development

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Embryology animation fertilization to development of the nervous system

01- Fertilization
02- Cleavage and blastocyst formation
03- Implantation
04- Gastrulation
05- Folding of the embryo
06- Development of body cavity
07- Pharyngeal arches, tongue, thymus, and thyroid
08- The development of the face and palate
09- Respiratory development
10- The development of the gastrointestinal tract
11- The development of the reproductive system
12- The development of the urinary tract
13- The development of the heart
14- The development of the vascular system
15- The development of the nervous system

#embryology #fertilization #development

Developmental biology part 3 : Gastrulation

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Gastrulation is a phase early in the embryonic development of most animals, during which the single-layered blastula is reorganized into a trilaminar (three-layered) structure known as the gastrula. These three germ layers are known as the ectoderm, mesoderm, and endoderm.[1][2]

Gastrulation takes place after cleavage and the formation of the blastula and primitive streak. Gastrulation is followed by organogenesis, when individual organs develop within the newly formed germ layers.[3] Each layer gives rise to specific tissues and organs in the developing embryo. The ectoderm gives rise to epidermis, and to the neural crest and other tissues that will later form the nervous system. The mesoderm is found between the ectoderm and the endoderm and gives rise to somites, which form muscle; the cartilage of the ribs and vertebrae; the dermis, the notochord, blood and blood vessels, bone, and connective tissue. The endoderm gives rise to the epithelium of the digestive system and respiratory system, and organs associated with the digestive system, such as the liver and pancreas.[4] Following gastrulation, cells in the body are either organized into sheets of connected cells (as in epithelia), or as a mesh of isolated cells, such as mesenchyme.[2][5]

The molecular mechanism and timing of gastrulation is different in different organisms. However, some common features of gastrulation across triploblastic organisms include: (1) A change in the topological structure of the embryo, from a simply connected surface (sphere-like), to a non-simply connected surface (torus-like); (2) the differentiation of cells into one of three types (endodermal, mesodermal, and ectodermal); and (3) the digestive function of a large number of endodermal cells.[6]

Lewis Wolpert, pioneering developmental biologist in the field, has been credited for noting that It is not birth, marriage, or death, but gastrulation, which is truly the most important time in your life.

The terms gastrula and gastrulation were coined by Ernst Haeckel, in his 1872 work Biology of Calcareous Sponges.[7]

Although gastrulation patterns exhibit enormous variation throughout the animal kingdom, they are unified by the five basic types of cell movements that occur during gastrulation: 1) invagination 2) involution 3) ingression 4) delamination 5) epiboly.[8] Source of the article published in description is Wikipedia. I am sharing their material. Copyright by original content developers of Wikipedia.
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Eric Wieschaus (Princeton) Part 1: Patterning Development in the Embryo



Following fertilization, the single celled embryo undergoes a number of mitotic divisions to produce a ball of cells called a blastula or blastoderm. Although these cells are all genetically identical, they gradually begin to express different gene products that reflect the regions of the adult body they will form. In my first lecture I discuss how these initial patterns of gene expression arise. In Drosophila, a maternally supplied transcription factor called Bicoid plays a particularly important role. Bcd RNA is anchored at the anterior end of the egg but is only translated after fertilization. From that anterior source, Bcd protein is thought to diffuse through the egg, establishing a concentration gradient that activates different genes at different thresholds. See more at

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