How Does the Embryo Take Form and Differentiate to Become an Organised Organism?”

Shortly after an egg is fertilized stem cells begin to form. These cells are programmed to form every organ and tissue in the body as the baby develops.

In an embryo, cytoplasmic determinants, material substances in an egg that influence the course of development, receive signals from the environment and neighboring cells. The uneven distribution of these molecules creates gradients that determine the orientation, such as the anterior and posterior, of the organism.

Using a salamander, proved that the cell nucleus from an early embryonic cell can effectively substitute for the nucleus in a fertilized egg.

Xenopus laevis and Danio rerio are two models that are extensively used to study early embryonic development, in particular, neurulation. During this practical Danio rerio was used as the model, however the advantages and disadvantages of the use of both models will be discussed herein.

The life of a human being starts when the sperm and ovum joins together to create a single cell. It then takes its form in the fallopian tubes. From day 0 until week 7, the cells go through several stages called: zygote, blastocyst, and finally develops to the embryonic stage. The zygote stage begins from day 0 and day 5. During this stage, the DNA of the father and DNA of the mother combines and a complete set of human genetic information is generated. At the completion of the zygote stage, it begins to divide and grows into another combination of cells called the blastocyst. The Blastocyst stage starts at day 5 and continues through day 10. In this stage, a few hundreds of cells develops in the lining of the uterus. The blastocyst consists

Centriole - these two features made of hollow tubules play a key role in cell division.

The brain, which is the command center for the whole body must go through many changes in order to reach its full potential. To begin, the once the sperm fertilizes the egg it becomes a zygote. After that happens within 12 hours, the single cell begins to divide to form a mass of homogenous cells. After 3 days the divisions form a mass of cells that continually divide to form the blastocyst. Within 5 days the blastocyst would have migrated to the uterus and hatched and began to invade into the uterine lining to implant. If it does implant by 1-2 weeks the embryo starts to separate into three distinct cell layers: the ectoderm, mesoderm, and endoderm. The ectoderm, which is the outer most layer, will form the skin and the peripheral nervous

The closure of the neural tube does not occur simultaneously throughout the ectoderm. This is best seen in those vertebrates (such as birds and mammals) whose body axis is elongated prior to neurulation. Figure 12.5 depicts neurulation in a 24-hour chick embryo. Neurulation in the cephalic (head) region is well advanced, while the caudal (tail) region of the embryo is still undergoing gastrulation. Regionalization of the neural tube also occurs as a result of changes in the shape of the tube. In the cephalic end (where the brain will form), the wall of the tube is broad and thick. Here, a series of swellings and constrictions define the various brain compartments. Caudal to the head region, however, the neural tube remains a simple tube that

I know this question wasn't directed for me so I hope that you don't mind that I respond, but in my opinion I think the embryonic period is the most critical period because so many of the important organs are forming during this time like the heart, brain, spinal cord, and the process of sexual differentiation. The embryonic period is the most important period when the mother should live a healthy lifestyle free from any type of teratogens. She and the baby will benefit greatly from doing this because it could prevent the baby from being

At the moment when the sperm penetrates the egg, it creates a cell called a zygote which has its own DNA. Already this cell has determined what the child will look and act like. So is this cell an organism? Scientists define an organism as a complex structure of interdependent elements constituted

What is known is that the forebrain roof plate starts to develop soon after neurulation, when roof plate cells, which are the first cohort of cell to exit the cell cycle (Kahane and Kalcheim, 1998) begin to form a thin monolayer. This is the time point when the roof plate starts expressing multiple signaling molecules such as members of the Bmp, Wnt and Fgf families exhibiting different gradients along the anterior-posterior axis (Crossley et al., 2001; Furuta et al., 1997; Shimogori et al., 2004). Roof plate development is a complex process and requires the activity of the same set of signaling molecules which later pattern the dorso-medial structures in the forebrain. Evidence gathered primarily from studies in the chick embryo suggest that correct dorsal-ventral patterning of the forebrain is a pre-requisite for subsequent establishment of roof plate identity. In fact the dorsal-ventral identity of the forebrain is acquired as early as the neural fold stage where Wnt signaling first imparts dorsal character to the forebrain cells which otherwise would exhibit ventral characteristics. However, Wnt signaling alone can only impart the initial dorsal forebrain characteristics manifested as the expression of certain markers. Nonetheless, Wnt signaling together with Fgf8 induces the definitive dorsal forebrain characteristics (Gunhaga et

Sea urchin embryos have been studied as model organisms for over 100 years. This organism is a great resource because of its straightforward artificial spawning, fertilization, and its embryo optical transparency. Also, the sea urchin simple organization makes it great to study morphogenetic movements and effects (Hardin et al., 1995).

1932). As such, yolk sac blood islands are speculated to form from the extra-embryonic mesoderm through the intermediary hemangioblast, which differentiate into centrally

transferred into the host will often be completed during the early stages of embryo development

The Spemann Organiser has a major role in the development of the central nervous system in the embryos of amphibians. The cells of the Spemann Organiser have a unique ability to alter the surrounding cells’ fates, in a process known as induction. The discovery of the Spemann organiser garnered large amounts of attention, causing Spemann to win the Nobel Prize in Medicine, in 1935, for his work in the discovery of induction. The Spemann organiser, as it has roles in developing the central nervous system, must turn off signals that encourage cells to transform into, for example, skin cells, and to turn on signals for cells that induce the formation of the central nervous system. It does this by releasing a number of molecules, including Chordin, Follistatin and Noggin, the main focus of this essay being on the function of Chordin. Chordin results