The Early Stages Of Embryo Development

1. Many experiments were conducted during the 1950s and 1960s with chick embryos and they showed that two patches of tissue essentially controlled the development of the pattern of bones inside limbs.  Describe at

Using these three articles (or more), you should tell the story of the discovery and developmental function (including the relevant signaling pathway) -

animal in the early stages of growth when it’s basic structure and organ development is forming.

Your friend’s dog, Spot, jumped onto a table with a terrarium housing your pet salamander, Lizzie. Unfortunately, the table tipped over and Spot has suffered a head injury which damaged the primary motor cortex. Lizzie lost most of the distal right forelimb in the accident. Please answer the following questions regarding the nervous system and regeneration, in a .docx, .pptx, or .pdf format.

How are medially-positioned progenitors affected by diffusible signals? The number of neurons belonging to populations found near or at the centre of the dorsoventral axis of the cord is influenced by signal levels, including Shh and BMPs. A moderate concentration of BMP signaling is needed to generate the correct number of medial interneurons. In zebrafish mutants in which a particular BMP protein is functionally reduced, there was a resulting increase in Lim1+ interneurons (medial interneurons) post-mitotically (Nguyen et al., 2000). Interestingly, further BMP reduction decreases medial interneuron counts, illustrating the fine balance of BMP levels that is needed to establish appropriate medial interneuron expression. Perturbing natural

inhibitory signals from the glia and the extracellular environment and forms scars rapidly. Not much

DRG isolation, plating, and axon elongation: Adult DRG from C1 to L1 will be dissected from SD rats ≥ 8 weeks of age using standard techniques.14,32,33 Dissected DRGs are treated in 0.25% collagenase-P (Boehringer Mannheim) in Neurobasal media (Invitrogen) for 1.5 hours followed by a treatment in 0.25% trypsin in cell dissociation buffer for an additional 1.5 hours. After trypsin inhibition, the pellet will be resuspended in complete medium and mechanically separated using a fire polished pasture pipet until the DRGs are completely dissociated. The DRG cells will be plated along the elongation interface and maintained in complete growth medium consisting of Neurobasal Media supplemented with B27 (Invitrogen), 1% FBS (Hyclone) and 1mM L-Glutamine (Invitrogen), 2.5g/L glucose, and 10μg/mL 2.5S nerve growth factor (Becton Dickinson). After cells attach, DRG cultures will be immediately treated with mitotic inhibitor cocktails consisting of 5 μM cytosine arabinoside, 20 μM 5-fluoro-2’-deoxyuridine and 20 μM uridine. Five days after plating, the axon fascicles spanning the two overlapping membranes will be elongated. Stretch-induced axon elongation is controlled by

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.

Irene Gutierrez thesis aims to understand the role of Shh in two very important aspects of brain development:

When calcium penetrates into the individual sarcomere (smallest unit of a muscle cell), they bind to troponin (a protein covering the active site on the actin i.e tropomyosin complex). This binding of the calcium and troponin alter the position of this tropomyosin complex, exposing the active site. This enables cross-bridges to be formed.

To visualize the sections and eventually the SNB neurons we used the computer where the photos were regrouped in a folder. The goal was to count the number of SNB motorneurons in each section and recorded in a chart. Then, we summed up the number of neurons per rat; and times it

In mice, this process starts around Embryonic Day 11.5 as the neural progenitor cells located in the Ventricular and Subventricular Zones (SVZ) migrate upwards to form what will later become Layers 2 through 6. Neurons are formed as these neural progenitor cells become Radial Glial Cells (RGC), a subpopulation of stem cells, and differentiate. The timing of the differentiation determines when neurons will form the lower or upper layers. When the differentiation occurs early in neurogenesis, the neurons migrate slightly to form the lower layers. In later neurogenesis, the differentiated neurons migrate past the lower layers and begin forming the upper layers. The formation of the upper layers tends to arise from differentiation of Intermediate Progenitor Cells (IPCs) rather than RGC differentiation. IPCs are formed from neural progenitor cells alongside RGCs (Kwan et al. 1538). While neurogenesis in humans may lead to differing relative sizes of the layers and SVZ, the structure of six specified layers is the same. The divisions between the layers do not occur in humans until around gestational week 9 to 11 (Deboer et al.

As stated previously, the proteins, a1-chimaerin and a2-chimaerin, are important in the facilitation of neural growth. The a2-chimaerin protein regulates the movement between the different neurons, so that neural structures can develop properly. When a mutation takes place in the CHN1 gene, it causes the a2-chimaerin to not work properly. This mutation causes some of the nerves that are created by the CHN1 proteins to either be underdeveloped or missing altogether. Jeon-Min Hwang and associates found that the absence of the CHN1 caused the subsequent absence of cranial nerves IV and VI (18). Cranial nerve four, also known as the trochlear nerves, serves to lower the eye as it is adducted by the superior oblique muscles; in

During the course of the past thirty years, the study of model organisms has become more significant in the study of embryological development. A model organism is a species that is easy to cultivate and monitor in a laboratory environment and is used to represent broad groups of organisms. Examples of successful and important model organisms include the Ascidia, Zebrafish, and Medeka species. Through intense researching of these organisms, scientists have been able to gain valuable insight into the developmental processes of many complex vertebrates, including humans.

In this essay, the role of Chordin in the Spemann’s organiser will be examined, as well as an outline of the Spemann Organiser’s discovery and formation in neural tissue. Chordin has a role in antagonising BMP, forming the dorsal-ventral axis, but it can be controlled if excess Chordin activation occurs. These aspects of Chordin will be examined throughout the following essay.