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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
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Home | Pregnancy Timeline | News Alerts |News Archive May 27, 2014

New parent.
In related work, galanin, a neuropeptide that can be stress-induced, and its cotransmitter, serotonin,
were found to play a possible role in stress-related disorders such as depression and anxiety.
The article was published online March 24 in the:
Proceedings of the National Academy of Sciences
.

 

 






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The neural path to becomming a parent

Harvard researchers identify neurons that regulate mouse ability to act as a parent. Good news for dads, the key to being a better parent is – literally – all in your head.

In a study using mice as the model animal, Higgins Professor of Molecular and Cellular Biology and Howard Hughes Investigator Catherine Dulac, have pinpointed galanin neurons in the brain's medial preoptic area (MPOA) that appear to regulate parental behavior. If similar neurons are at work in humans, it could offer clues to the treatment of conditions like post-partum depression.

The study was published on May 15 in Nature.


"If you look across different animal species, there are some species in which the father contributes to caring for the young – sometimes the work is divided equally, sometimes the father does most of the work – and there are species in which the father does nothing.

"The essential question is where is that variability coming from? We may be tempted to say that the mom has the neurons required to engage in parental behavior, and dads don't – this paper shows that's wrong."

Catherine Dulac, PhD, Howard Hughes Investigator,


It's long been known, according to Dulac, that mice have stereotypical reactions to pups. Among sexually-experienced mice, both males and females care for pups by building nests, grooming and huddling with them. Virgin females exhibit the same maternal behavior, while virgin males typically attack and kill pups.


Using genetic tools, Herbert Wu in Dulac's lab collabored with other researchers to activate galanin neurons in virgin males, the results were startling.

Rather than attacking pups, the males immediately began to groom the pups.

When galanin neurons were killed in parents, they either ignored the pups altogether, or virgin females behaved like males and attacked the pups.


Dulac and colleagues began exploring the roots of parenting behavior after making an unusual observation in female mice. Females that have no olfactory neurons responsible for certain innate behavior — the vomeronasal organ (VNO) — behave like male mice.

"We came to the conclusion that the VNO in female mice represses male - like behavior," Dulac said. "So if there is repression of that behavior in females — there might be a parallel system in males that drives female - like behavior."

While the discovery of galanin neurons in the brain's medial preoptic area (MPOA) suggests the answer is yes, it also raises another question – why the neurons would be present in males if they aren't useful.

Researchers found these neurons are useful, but only after the male has mated. They don't become active for three weeks after mating occurs – the exact period of time it takes a female mouse to gestate pups.

"The male won't kill the pups born three weeks following his first mating, because these pups may very well be his own offspring," Dulac explains. "Even if you remove males immediately after mating and segregate them from the females, half of the males will behave paternally after three weeks have passed. Mating seems to trigger a clock leading to paternal behavior."


Though it's not yet clear whether similar neural pathways exist in humans, galanin neurons are concentrated in a brain region responsible for many innate behaviors, such as feeding and sleep.

Other neurons in the same brain region have been shown to be conserved from mice across many mammal species, including humans.


"I would be extremely surprised if these neurons did not exist in humans," adds Dulac. "What does it mean? It means that mothers can parent and fathers can parent. But what is really interesting, I think, is we have identified an instinctive behavior – a very important social behavior – and have access to how it's regulated."

Understanding how parental behavior is regulated, Dulac believes, also opens a door to understanding how that behavior can break down, potentially leading to conditions like post-partum depression.

Dulac: "It is known that post-partum depression has a very close association with stress levels, particularly among first-time mothers. One interesting hypothesis is that galanin neurons in the MPOA have stress hormone receptors that can inhibit their function.

"Parental behavior is many things. It's grooming, it's building a nest, it's protecting pups – the male is able to do it all. The research tells us that the male brain has the neurons to be paternal, but somehow those neurons are repressed. But we now know, yes, dads can do it all."

Abstract
Mice display robust, stereotyped behaviours towards pups: virgin males typically attack pups, whereas virgin females and sexually experienced males and females display parental care. Here we show that virgin males genetically impaired in vomeronasal sensing do not attack pups and are parental. Furthermore, we uncover a subset of galanin-expressing neurons in the medial preoptic area (MPOA) that are specifically activated during male and female parenting, and a different subpopulation that is activated during mating. Genetic ablation of MPOA galanin neurons results in marked impairment of parental responses in males and females and affects male mating. Optogenetic activation of these neurons in virgin males suppresses inter-male and pup-directed aggression and induces pup grooming. Thus, MPOA galanin neurons emerge as an essential regulatory node of male and female parenting behaviour and other social responses. These results provide an entry point to a circuit-level dissection of parental behaviour and its modulation by social experience.
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