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Positional specification of nuclei in a shared cytoplasm before complete cellularization, allowing spatial signals to influence nuclear transcription without conventional cell boundaries.
Formation of individual cell boundaries around nuclei previously sharing a common cytoplasmic compartment.
A vertebrate embryonic population arising near the neural border, with migratory descendants contributing to cranial connective and skeletal tissues, peripheral neurons and glia, pigment cells and other derivatives. Individual cells and axial populations have restricted subsets of these potentials.
An embryonic germ layer giving rise to epidermal and neural tissues, including the origin of vertebrate neural crest.
An embryonic germ layer supplying diverse tissues, including muscle and much connective tissue; particular connective tissues can also arise from ectoderm-derived neural crest.
A localised ectodermal thickening or precursor territory contributing to cranial sensory structures and associated cells. Placodes and neural crest make distinct interacting contributions.
An embryonic germ layer contributing to the epithelial lining of much of the digestive and respiratory systems and associated organs.
A principal embryonic cellular layer established through gastrulation; the classical three-layer organisation comprises ectoderm, mesoderm and endoderm.
The hypothesis that integration of neural crest, ectodermal placodes and other cranial tissues helped enable vertebrate head innovation and more active feeding. Developmental necessity, morphological diversification and ancestral ecological reconstruction are different evidential claims.
Study of how changes in biological development contribute to evolution. Comparative gene expression, developmental perturbations and phylogenetics can connect inherited mechanisms to new forms.
Recruitment of an existing gene or gene regulatory network to a new developmental deployment or function. Changing the location of gene expression can generate a new structure using inherited cellular activities.
Shared inherited developmental machinery underlying structures whose final organization can differ substantially. A shared regulator alone does not establish that two entire organs have the same historical origin.
Unequal accessibility of phenotypic variants caused by the organization of biological development. Repeated outcomes can reflect this structure as well as repeated natural selection; accessibility and selective advantage are different questions.
Organization of biological development into relatively separable components. It can allow one structure or deployment to evolve with fewer effects on others, without implying complete independence.
Assignment of later cellular or tissue contributions to identified precursor regions. Labels require positional and persistence controls; observed fate alone is not a complete test of evolutionary identity.
Pinned article: Introduction to the OurBigBook Project
Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
Intro to OurBigBook
. Source. We have two killer features:
- topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculusArticles of different users are sorted by upvote within each article page. This feature is a bit like:
- a Wikipedia where each user can have their own version of each article
- a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
Figure 1. Screenshot of the "Derivative" topic page. View it live at: ourbigbook.com/go/topic/derivativeVideo 2. OurBigBook Web topics demo. Source. - local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
- to OurBigBook.com to get awesome multi-user features like topics and likes
- as HTML files to a static website, which you can host yourself for free on many external providers like GitHub Pages, and remain in full control
Figure 2. You can publish local OurBigBook lightweight markup files to either OurBigBook.com or as a static website.
Figure 3. Visual Studio Code extension installation.
Figure 5. . You can also edit articles on the Web editor without installing anything locally. Video 3. Edit locally and publish demo. Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension. 
- Infinitely deep tables of contents:
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact