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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 23, 2013

 

Professor Allan Herbison, has discovered the key cellular location of signalling
between a small protein known as kisspeptin* and its receptor, called Gpr54.
Kisspeptin is known to be crucial for fertility in humans, and vital for ovulation to occur.

Image source: Reproduction-Online.org




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Final piece in puzzle of brain circuitry of fertility

In a landmark discovery, the final piece in the puzzle of understanding how the brain circuitry vital to normal fertility in humans and other mammals operates has been put together by researchers at New Zealand's University of Otago.

Their new findings, which appear in the leading international journal Nature Communications, will be critical to enabling the design of novel therapies for infertile couples as well as new forms of contraception.

The research team, led by Otago neuroscientist Professor Allan Herbison, have discovered the key cellular location of signalling between a small protein known as kisspeptin* and its receptor, called Gpr54. Kisspeptin had earlier been found to be crucial for fertility in humans, and in a subsequent major breakthrough Professor Herbison showed that this molecule was also vital for ovulation to occur.


In the latest research, Professor Herbison and colleagues at Otago and Heidelberg University, Germany, provide conclusive evidence that the kisspeptin-Gpr54 signalling occurs in a small population of nerve cells in the brain called gonadotropin-releasing hormone (GnRH) neurons.

Using state-of-the-art techniques, the researchers studied mice that lacked Gpr54 receptors in only their GnRH neurons and found that these did not undergo puberty and were infertile.

They then showed that infertile mice could be rescued back to completely normal fertility by inserting the Gpr54 gene into just the GnRH neurons.


Professor Herbison says the findings represent a substantial step forward in enabling new treatments for infertility and new classes of contraceptives to be developed.

"Infertility is a major issue affecting millions of people worldwide. It's currently estimated that up to 20 per cent of New Zealand couples are infertile, and it is thought that up to one-third of all cases of infertility in women involve disorders in the area of brain circuitry we are studying.

"Our new understanding of the exact mechanism by which kisspeptin acts as a master controller of reproduction is an exciting breakthrough which opens up avenues for tackling what is often a very heart-breaking health issue. Through detailing this mechanism we now have a key chemical switch to which drugs can be precisely targeted," Professor Herbison says.

As well as the findings' benefits for advancing new therapies for infertility and approaches to controlling fertility, they suggest that targeting kisspeptin may be valuable in treating diseases such as prostate cancer that are influenced by sex steroid hormone levels in the blood, he says.

Professor Herbison noted that the research findings represent a long-standing collaborative effort with the laboratory of Professor Gunther Schutz at Heidelberg University, Germany.

Professor Herbison is Director of the University's Centre for Neuroendocrinology, which is the world-leading research centre investigating how the brain controls fertility.

"We are delighted to have published this work in one of the top scientific journals and also to be able to maintain the leading role of New Zealand researchers in understanding fertility control," he says.

Abstract
Signaling between kisspeptin and its receptor, G-protein-coupled receptor 54 (Gpr54), is now recognized as being essential for normal fertility. However, the key cellular location of kisspeptin–Gpr54 signaling is unknown. Here we create a mouse with a GnRH neuron-specific deletion of Gpr54 to assess the role of gonadotropin-releasing hormone (GnRH) neurons. Mutant mice are infertile, fail to go through puberty and exhibit markedly reduced gonadal size and follicle-stimulating hormone levels alongside GnRH neurons that are unresponsive to kisspeptin. In an attempt to rescue the infertile phenotype of global Gpr54−/− mutants, we use BAC transgenesis to target Gpr54 to the GnRH neurons. This results in mice with normal puberty onset, estrous cyclicity, fecundity and a recovery of kisspeptin’s stimulatory action upon GnRH neurons. Using complimentary cell-specific knockout and knockin approaches we demonstrate here that the GnRH neuron is the key site of kisspeptin–Gpr54 signaling for fertility.

*Kisspeptin was originally named after the Hershey Kiss chocolate by US researchers based in Hershey, Pennsylvania. At the time they had no idea that it had a role in fertility.

Original press releas: http://www.eurekalert.org/pub_releases/2013-09/uoo-fpf091913.php