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Welcome to The Visible Embryo, a comprehensive educational resource on human development from conception to birth.

The Visible Embryo provides visual references for changes in fetal development throughout pregnancy and can be navigated via fetal development or maternal changes.

The National Institutes of Child Health and Human Development awarded Phase I and Phase II Small Business Innovative Research Grants to develop The Visible Embryo. Initally designed to evaluate the internet as a teaching tool for first year medical students, The Visible Embryo is linked to over 600 educational institutions and is viewed by more than one million visitors each month.

Today, The Visible Embryo is linked to over 600 educational institutions and is viewed by more than 1 million visitors each month. The field of early embryology has grown to include the identification of the stem cell as not only critical to organogenesis in the embryo, but equally critical to organ function and repair in the adult human. The identification and understanding of genetic malfunction, inflammatory responses, and the progression in chronic disease, begins with a grounding in primary cellular and systemic functions manifested in the study of the early embryo.

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Pregnancy Timeline by SemestersFetal liver is producing blood cellsHead may position into pelvisBrain convolutions beginFull TermWhite fat begins to be madeWhite fat begins to be madeHead may position into pelvisImmune system beginningImmune system beginningPeriod of rapid brain growthBrain convolutions beginLungs begin to produce surfactantSensory brain waves begin to activateSensory brain waves begin to activateInner Ear Bones HardenBone marrow starts making blood cellsBone marrow starts making blood cellsBrown fat surrounds lymphatic systemFetal sexual organs visibleFinger and toe prints appearFinger and toe prints appearHeartbeat can be detectedHeartbeat can be detectedBasic Brain Structure in PlaceThe Appearance of SomitesFirst Detectable Brain WavesA Four Chambered HeartBeginning Cerebral HemispheresFemale Reproductive SystemEnd of Embryonic PeriodEnd of Embryonic PeriodFirst Thin Layer of Skin AppearsThird TrimesterSecond TrimesterFirst TrimesterFertilizationDevelopmental Timeline
CLICK ON weeks 0 - 40 and follow along every 2 weeks of fetal development
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Home | Pregnancy Timeline | News Alerts |News Archive Sep 25, 2013

 

Generalized diagram of G protein-gated ion channel
Generally, G protein-gated ion channels are specific ion channels located in the plasma membrane of cells that are directly activated by a family of associated proteins. Ion channels allow for the selective movement of certain ions across the plasma membrane in cells. More specifically, in nerve cells, along with ion transporters, they are responsible for maintaining the electrochemical gradient across the cell.

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How heart cells communicate to synchronize heart

New research from Western University in London, Canada, is leading to a better understanding of what happens during heart failure. The new information could lead to better therapeutics or more accurate prediction of risk.

The research led by Robarts Research Institute scientists Robert Gros, PhD, and Marco Prado, PhD, along with graduate student Ashbeel Roy found the heart is regulated not only by nervous systems but also by heart cells sending messages to each other through the release of the neurotransmitter acetylcholine (ACh). The research has been published online by The FASEB Journal.

As Gros explains, heart activity is regulated by two nervous systems: the sympathetic and the parasympathetic. The sympathetic acts like an accelerator, speeding up the heart and the parasympathetic acts like a brake, decreasing the heart rate. When these systems get dysregulated or out of whack, it can lead to heart failure.


"But the heart is not well innervated, in other words, there are very few nerves to control the heart. So we wanted to know how the signal from the nerve is communicated throughout the heart. A neuronal system is nerve-based but now we're talking about a non-neuronal system, which means it's not in any nerve tissue but found in the heart cells themselves.

We've shown how the nerve sends a signal and individual heart cells pick up that signal; they can transduce that signal by the release of ACh from one cell to the next. It's the propagation of this signal that regulates the heart. Now we need to look at how this system changes in heart failure."

Robert Gros, PhD, associate professor, Departments of Physiology & Pharmacology and Medicine, Western's Schulich School of Medicine & Dentistr,y and scientist in Vascular Biology Research Group at Robarts


In collaboration with Robarts' scientist Vania Prado, PhD, Gros tested the theory using mice which were engineered so that their heart cells exclusively, could not release ACh. Under non-stressful conditions the mutant mice had normal heart rates. But when they exercised, these mice had a far greater increase in their heart rate, and it took longer for them to return to their pre-exercise heart rate, as compared to control mice.


The results suggest the heart cell derived ACh may boost parasympathetic signaling to counterbalance sympathetic activity.


Gros calls the research a kick start, because if this non neuronal source of ACh is playing such an important role in the heart, it's probably important in other organs as well.

Abstract
Heart activity and long-term function are regulated by the sympathetic and parasympathetic branches of the nervous system. Parasympathetic neurons have received increased attention recently because acetylcholine (ACh) has been shown to play protective roles in heart disease. However, parasympathetic innervation is sparse in the heart, raising the question of how cholinergic signaling regulates cardiomyocytes. We hypothesized that non-neuronal secretion of ACh from cardiomyocytes plays a role in cholinergic regulation of cardiac activity. To test this possibility, we eliminated secretion of ACh exclusively from cardiomyocytes by targeting the vesicular acetylcholine transporter (VAChT). We find that lack of cardiomyocyte-secreted ACh disturbs the regulation of cardiac activity and causes cardiomyocyte remodeling. Mutant mice present normal hemodynamic parameters under nonstressful conditions; however, following exercise, their heart rate response is increased. Moreover, hearts from mutant mice present increased oxidative stress, altered calcium signaling, remodeling, and hypertrophy. Hence, without cardiomyocyte-derived ACh secretion, hearts from mutant mice show signs of imbalanced autonomic activity consistent with decreased cholinergic drive. These unexpected results suggest that cardiomyocyte-derived ACh is required for maintenance of cardiac homeostasis and regulates critical signaling pathways necessary to maintain normal heart activity. We propose that this non-neuronal source of ACh boosts parasympathetic cholinergic signaling to counterbalance sympathetic activity regulating multiple aspects of heart physiology.—Roy, A., Fields, W. C., Rocha-Resende, C., Resende, R. R., Guatimosim, S., Prado, V. F., Gros, R., Prado, M. A. M. Cardiomyocyte-secreted acetylcholine is required for maintenance of homeostasis in the heart.

The research was supported by the Heart and Stroke Foundation of Ontario, the Canadian Institutes of Health Research and the Canada Foundation for Innovation.

Original press releas: http://www.schulich.uwo.ca/schulichhome/articles/2013/09/24/new-research-shows-how-heart-cells-communicate-to-regulate-heart-activity-