Processes
Nerve Growth Factor
By Adam R. Navis
Nerve growth factor (NGF) is a signaling protein and growth factor implicated in a wide range of development and maintenance functions. NGF was discovered through a series of experiments in the 1950s on the development of the chick nervous system.
Created 2007-10-30. Modified 9 months ago.Chemical Induction
By Adam R. Navis
Research in chemical induction seeks to identify the compound or compounds responsible for differentiation in a developing embryo. Soren Lovtrup compared the search for these compounds to the search for the philosopher's stone.
Created 2007-10-30. Modified 9 months ago.Epidermal Growth Factor
By Adam R. Navis
Epidermal growth factor is a signaling molecule that stimulates the growth of epidermal tissues during development and throughout life. Stanley Cohen discovered epidermal growth factor (EGF) during studies of nerve growth factor as a side effect of other experiments.
Created 2007-10-30. Modified 9 months ago.Quickening
By Katherine Brind'Amour
Quickening, the point at which a pregnant woman can first feel the movements of the growing embryo or fetus, has long been considered a pivotal moment in pregnancy.
Created 2007-10-30. Modified 9 months ago.Slime Mold Video
By Mary E. Sunderland
This video is composed of a sequence of films created by John Tyler Bonner in the 1940s to show the life cycle of the cellular slime mold Dictyostelium discoideum.
Created 2008-05-02. Modified 9 months ago.Morphogenesis
By Mary E. Sunderland
The term morphogenesis generally refers to the processes by which order is created in the developing organism. This order is achieved as differentiated cells carefully organize into tissues, organs, organ systems, and ultimately the organism as a whole.
Created 2008-05-09. Modified 9 months ago.Homunculus
By Cera R. Lawrence
The term homunculus is Latin for "little man." It is used in neurology today to describe the map in the brain of sensory neurons in each part of the body (the somatosensory homunculus).
Created 2008-08-13. Modified 9 months ago.Hartsoeker's Homunculus Sketch from Essai de Dioptrique
By Cera R. Lawrence
This embryology image is a pencil sketch by Nicolaas Hartsoeker, published as part of his 1694 French-language paper entitled Essai de Dioptrique, a semi-speculative work describing the sorts of new scientific observations that could be done using magnifying lenses.
Created 2008-08-14. Modified 9 months ago.Leonardo da Vinci's Embryological Drawings of the Fetus
By Hilary Gilson
Leonardo da Vinci's embryological drawings of the fetus in the womb and his accompanying observational annotations are found in the third volume of his private notebooks.
Created 2008-08-19. Modified 9 months ago.Test-Tube Baby
By Stephen C. Ruffenach
A test-tube baby is the product of a successful human reproduction that results from methods beyond sexual intercourse between a man and a woman and instead utilizes medical intervention that manipulates both the egg and sperm cells for successful fertilization.
Created 2009-01-13. Modified 9 months ago.Regeneration
By Mary E. Sunderland
Regeneration is a fascinating phenomenon.
Created 2009-06-10. Modified 9 months ago.Sperm Capacitation
By Stephen Ruffenach
Sperm capacitation refers to the physiological changes spermatozoa must undergo in order to have the ability to penetrate and fertilize an egg.
Created 2009-07-07. Modified 9 months ago.Ectopic Pregnancy
By Tian Zhu
Many difficulties can arise with a pregnancy even after the sperm successfully fertilizes the oocyte. A major problem occurs if the fertilized egg tries to implant before reaching its normal implantation site, the uterus.
Created 2010-05-06. Modified 9 months ago.Abortion
By Christina Raup
Abortion is the removal of the embryo or fetus from the womb, before birth can occur-either naturally or by induced labor.
Created 2010-06-10. Modified 9 months ago.Inducing Fertilization and Development in Sand Dollars
By Karen Wellner
Sand dollars are common marine invertebrates in the phylum Echinodermata and share the same class (Echinoidea) as sea urchins. They have served as model laboratory organisms for such embryologists as Frank Rattray Lillie and Ernest Everett Just.
Created 2010-06-24. Modified 9 months ago.The Yale Embryo
By Kaitlin Smith
In 1934 a fourteen-day-old embryo was discovered during a postmortem examination and became famous for being the youngest known human embryo specimen at the time.
Created 2010-06-28. Modified 9 months ago.Reassessment of Carrel's Immortal Tissue Culture Experiments
By Lijing Jiang
In the 1910s, Alexis Carrel, a French surgeon and biologist, concluded that cells are intrinsically immortal. His claim was based on chick-heart tissue cultures in his laboratory that seemed to be able to proliferate forever.
Created 2010-06-28. Modified 9 months ago.Umbilical Cord Blood Stem Cells (UCBSC)
By Angel Lopez
Umbilical cord blood (UCB) stem cells are hematopoietic stem cells (HSC) that are recovered from the blood of the umbilical cord and placenta after birth. Umbilical cord blood is rich in cells that express the CD34 molecule, a surface protein that identifies cells as stem cells.
Created 2010-07-01. Modified 9 months ago.Teratomas
By Christina Raup
Teratomas are embryonal tumors that normally arise from germ cells and are typically benign. They are defined as being composed either of tissues that are foreign to the area in which they form, or of tissues that derive from all three of the germ layers.
Created 2010-07-01. Modified 9 months ago.Amniocentesis Prior to 1980
By Kristin Kelley
The extraembryonic membranes that surround and originate from the embryos of vertebrates such as birds, reptiles, and mammals are crucial to their development.
Created 2010-09-02. Modified 9 months ago.Fate Map
By Corinne DeRuiter
Early development occurs in a highly organized and orchestrated manner and has long attracted the interest of developmental biologists and embryologists.
Created 2010-09-08. Modified 9 months ago.Circulatory Changes at Birth
By Brad Jacobson
When placental mammals are born their circulatory systems undergo radical changes as the newborns are prepared for independent life. The lungs are engaged, becoming the primary source of fresh oxygen, replacing the placental barrier as a means for blood-gas exchange.
Created 2010-09-12. Modified 9 months ago.The Effects of Thalidomide on Embryonic Development
By Tristan Cooper-Roth
Embryogenesis is an intricate process that can easily be disrupted by means of teratogenic agents.
Created 2010-09-12. Modified 9 months ago.Human Embryonic Stem Cells
By Ke Wu
Stem cells are undifferentiated cells that are capable of dividing for long periods of time and can give rise to specialized cells under particular conditions. Embryonic stem cells are a particular type of stem cell derived from embryos.
Created 2010-09-13. Modified 9 months ago.Homeobox Genes and the Homeobox
By Brad Jacobson
Homeobox genes are a cluster of regulatory genes that are spatially and temporally expressed during early embryological development.
Created 2010-10-11. Modified 9 months ago.Hematopoietic Stem Cells
By Angel Lopez
The discovery of hematopoietic stem cells (HSCs) provided a pioneering step in stem cell research. HSCs are a type of multipotent adult stem cell, characterized by their ability to self-renew and differentiate into erythrocyte (red blood cell) and leukocyte (white blood cell) cell lineages.
Created 2010-10-11. Modified 9 months ago.Somites: Formation and Role in Developing the Body Plan
By Corinne DeRuiter
Somites are blocks of mesoderm that are located on either side of the neural tube in the developing vertebrate embryo.
Created 2010-10-20. Modified 9 months ago.Process of Eukaryotic Embryonic Development
By Inbar Maayan
All sexually reproducing, multicellular diploid eukaryotes begin life as embryos. Understanding the stages of embryonic development is vital to explaining how eukaryotes form and how they are related on the tree of life.
Created 2010-10-20. Modified 9 months ago.Tissue Engineering
By Angel Lopez
Tissue engineering is a field of regenerative medicine that integrates the knowledge of scientists, physicians, and engineers into the construction or reconstruction of human tissue.
Created 2010-10-29. Modified 9 months ago.Stem Cells
By Ke Wu
According to the US National Institutes of Health (NIH), the standard American source on stem cell research, three characteristics of stem cells differentiate them from other cell types: (1) they are unspecialized cells that (2) divide for long periods, renewing themselves and (3) can give rise t
Created 2010-10-29. Modified 9 months ago.Post-Coital Oral Emergency Contraception
By Sarah Ly
Post-coital oral emergency contraception is used for the prevention of pregnancy after intercourse. The contraception comes in the form of pills, often collectively referred to as morning-after pills.
Created 2011-03-03. Modified 9 months ago.Embryonic Differentiation in Animals
By Sarah Ly
Embryonic differentiation is the process of development during which embryonic cells specialize and diverse tissue structures arise. Animals are made up of many different cell types, each with specific functions in the body.
Created 2011-03-03. Modified 9 months ago.Gastrulation in Xenopus
By Inbar Maayan
The process of gastrulation allows for the formation of the germ layers in metazoan embryos, and is generally achieved through a series of complex and coordinated cellular movements. The process of gastrulation can be either diploblastic or triploblastic.
Created 2011-03-10. Modified 9 months ago.Meiosis in Humans
By Inbar Maayan
Meiosis, the process by which sexually-reproducing organisms generate gametes (sex cells), is an essential precondition for the normal formation of the embryo.
Created 2011-03-24. Modified 9 months ago.Rh Incompatibility in Pregnancy
By Nathalie Antonios
Rh incompatibility occurs when a pregnant woman whose blood type is Rh-negative is exposed to Rh-positive blood from her fetus, leading to the mother s development of Rh antibodies.
Created 2011-04-08. Modified 9 months ago.The French Flag Model
By Jack Resnik
The French flag model represents how embryonic cells receive and respond to genetic information and subsequently differentiate into patterns.
Created 2011-05-19. Modified 9 months ago.Hamburger-Hamilton Staging Series (1951)
By Maria Doty
In 1951 Viktor Hamburger and Howard Hamilton created an embryonic staging series from a combination of photographs and drawings from other researchers. The Hamburger-Hamilton stages are a sequence of images depicting 46 chronological stages in chick development.
Created 2011-06-10. Modified 9 months ago.Nuclear Transplantation
By Sean Cohmer
Nuclear transplantation is a method in which the nucleus of a donor cell is relocated to a target cell that has had its nucleus removed (enucleated).
Created 2011-06-14. Modified 9 months ago.Hensen's Node
By Maria Doty, Corinne DeRuiter
A node, or primitive knot, is an enlarged group of cells located in the anterior portion of the primitive streak in a developing gastrula. The node is the site where gastrulation, the formation of the three germ layers, first begins.
Created 2011-06-21. Modified 9 months ago.Gastrulation in Gallus gallus (Domestic Chicken)
By Corinne DeRuiter, Maria Doty
Gastrulation is an early stage in embryo development in which the blastula reorganizes into three germ layers: the ectoderm, the mesoderm, and the endoderm. Gastrulation occurs after cleavage but before neurulation and organogenesis.
Created 2011-06-21. Modified 9 months ago.Mechanistic Realization of the Turtle Shell
By Guido Caniglia
Turtle morphology is unlike that of any other vertebrate. The uniqueness of the turtle's bodyplan is attributed to the manner in which the turtle's ribs are ensnared within its hard upper shell.
Created 2011-10-10. Modified 9 months ago.Essay: Homology
By Ingo Brigandt
Homology is a central concept of comparative and evolutionary biology, referring to the presence of the same bodily parts (e.g., morphological structures) in different species.
Created 2011-11-23. Modified 3 months ago.The Carapacial Ridge of Turtles
By Guido Caniglia
Two main elements characterize the skeletal morphology of turtles: the carapace and the plastron. For a turtle, the carapacial ridge begins in the embryo as a bulge posterior to the limbs but on both sides of the body.
Created 2012-01-01. Modified 9 months ago.Multi-Fetal Pregnancy
By Corinne DeRuiter
In humans, multi-fetal pregnancy occurs when a mother carries more than one fetus during the pregnancy. The most common multi-fetal pregnancy is twins, but mothers have given birth to up to eight children (octuplets) from a single pregnancy.
Created 2012-01-01. Modified 9 months ago.Spemann-Mangold Organizer
By Samuel Philbrick, Erica O'Neil
The Spemann-Mangold organizer, also known as the Spemann organizer, is a cluster of cells in the developing embryo of an amphibian that induces development of the central nervous system.
Created 2012-01-12. Modified 9 months ago.Bicoid
By Jack Resnik
Bicoid is the protein product of a maternal-effect gene unique to flies of the genus Drosophila . In 1988 Christiane Nüsslein-Volhard identified bicoid as the first known morphogen .
Created 2012-06-02. Modified 9 months ago.Mesenchyme
By Kate MacCord
Mesenchyme is a type of animal tissue comprised of loose cells embedded in a mesh of proteins and fluid, called the extracellular matrix.
Created 2012-09-14. Modified 9 months ago.Gastrulation in Mus musculus (common house mouse)
By Justin M. Wolter
As mice embryos develop, they undergo a stage of development called gastrulation. The hallmark of vertebrate gastrulation is the reorganization of the inner cell mass (ICM) into the three germ layers: ectoderm, mesoderm, and endoderm.
Created 2012-10-04. Modified 9 months ago.