embryos

Early in development, human embryos have a sizeable fishlike tail, which begins to disappear about seven weeks into development. It’s bones and tissues are simply reabsorbed by the body. Rarely, however, it doesn’t regress completely and a baby is born with a tail projecting from the base of its spine…some tails are an inch long, others nearly a foot. And they aren’t just simple flaps of skin, but can have hair, muscles, blood vessels, and nerves. Some can even wiggle! Fortunately, these awkward protrusions are easily removed by surgeons.

What could this mean, other than that we still carry a development program for making tails? Indeed, recent genetic work has shown that we carry the same genes that make tails in animals like mice, but these genes are normally deactivated in human fetuses.
—  Jerry Coyne, Why Evolution is True

26 January 2015

Granules of Fate

To make proteins, instructions encoded in DNA are first transcribed into a similar type of molecule called RNA, which in most cells is concentrated into clumps called RNA granules. In a single-celled embryo of the microscopic worm C. elegans (pictured at three separate moments), the behaviour of RNA granules (stained green) plays a key role in development. The granules condense into a gel-like state at one end and when the cell divides, the front forms a cell that will become bodily tissues while the back becomes a germ cell, which forms eggs or sperm. Now, researchers have identified a group of proteins floating around the cell that drive this shift between the dispersed and condensed state (shown here left to right). Without them, RNA granules failed to assemble, rendering the worms infertile. These findings add to our understanding of how fertilised eggs make early decisions that determine development.

Written by Daniel Cossins

Image by Jennifer Wang
Johns Hopkins University School of Medicine
Originally published under a Creative Commons Licence (BY 4.0)
Research published in eLife, December 2014

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Bilateral Gynandromorphism

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Animals with bilateral gynandromorphism display the outward appearance of a female on one side of their body, and the appearance of a male on the other. It can occur when the sex chromosomes fail to separate during cell division in early development, a process known as nondisjunction. As a result of this failure, some of the animal’s cells have a female genotype, and others have a male genotype, giving rise to an animal with both male and female characteristics. They have both male and female tissues.

With mammalian development – including humans – after the two gamete cells (sperm and ova) fuse, the zygote’s somatic cells begin to grow and develop into whatever body plan it’s forming. The embryo remains sexually indifferent until certain genes switch on and sex-determining hormones are secreted. And for a long time it was thought all vertebrates developed in this same manner. But it looks like birds follow a completely different plan of action. Avian somatic cells don’t wait to get their cue from the gonads, and seem to already “know” their own sexual identity before any sex-determining hormones are secreted.

Named cell autonomous sex identity (CASI), the phenomenon runs counter to the prevailing ideas of development of sexual traits in birds, and explains why a gynandromorph can display female traits on one side and rooster traits on the other in the same bird. The male or female cells are dominant on the respective sides. This could also apply to insects and other animals in which this type of gynandromorphism occurs.

I KNOW THIS QUOTE IS OLD BUT I STILL LIKE IT anyway i hope you had a merry christmas 

Babies with Three Parents Possible within Three Years

Researchers have secured £6m in funding to develop the groundbreaking treatment which could prevent genetic conditions affecting the heart, muscle or brain being passed on to children and future generations.

But the method is controversial because it involves transferring the parents’ DNA into a donor egg, meaning the resulting child would inherit a tiny fraction of their genetic coding from a third party.

While regulations currently forbid scientists from implanting such eggs into patients, the Wellcome Trust and Newcastle University has announced a £5.8m package for further lab-based research aimed at assessing the safety of the technique.

Read More

Scientists Clone Human Embryos To Make Stem Cells : Shots

The achievement is a long-sought step toward harnessing the potential power of such cells to treat diseases. But the discovery raises ethical concerns because it brings researchers closer to cloning humans, and involves creating and then destroying human embryos for research purposes.

Graphic Source: Mitalipov Lab/OHSUGraphic
Credit: Adapted for NPR by Alyson Hurt