Because life is too short to live without science.

ohyeahdevelopmentalbiology: raptinawe: This confocal...

Sat, 18 May 2013 10:54:28 +0100

raptinawe:

This confocal micrograph shows stage V–VI oocytes (800–1000 micron diameter) of an African clawed frog (Xenopus laevis), a model organism used in cell and developmental biology research. Each oocyte is surrounded by thousands of follicle cells, shown in the image by staining DNA blue. Blood vessels, which provide oxygen to the oocyte and follicle cells, are shown in red. The ovary of each adult female Xenopus laevis contains up to 20 000 oocytes. Mature Xenopus laevis oocytes are approximately 1.2 mm in diameter, much larger than the eggs of many other species. (Photo by Vincent Pasque, University of Cambridge/Wellcome Images)

(via Up Close: 2012 Wellcome Image Awards)

biomedicalephemera: Top: Uterine lining at 5 1/2 months,...

Fri, 17 May 2013 09:14:19 +0100

biomedicalephemera:

Top: Uterine lining at 5 1/2 months, displaying thin maternal separation from fetus, and high level of placental implantation
Center: Relation of placenta to uterus at 5 weeks and 8.5 months
Bottom: Major arteries and veins of the placenta

Did you know that the placenta is a temporary organ that’s actually created by the fetus, and not the woman?

The human female is a curious creature; like our close great ape cousins, but unlike almost all other mammals, they build up a thick barrier in the uterine wall, to protect against any potential embryo that might implant itself. When there’s no embryo implantation, the thickened wall is shed, in the process known as menstruation.

The thing is, most mammals don’t menstruate. They go into heat, and occasionally shed uterine lining (if the uterus is scratched, or an egg tries to implant but fails, for example), but there’s no regular cycle of bloody discharge relating to breeding. This is because other mammals go through triggered decidualization (developing a uterine lining only when a fertilized egg begins to implant itself), while the great apes (and a couple other convergently evolved families, including bats) experience spontaneous decidualization, where they develop a thick uterine lining during every ovulation, before an egg can even attempt to implant itself.

Why the different linings? Well, it turns out that there are three types of mammal placentas (remember, placentas are developed by the embryo/fetus, not the mother):

Epitheliochordal, which is completely superficial, and does not connect in any significant way to the mother’s body. The endometrial epithelium, connective tissue, and uterine epithelium are all preserved and undisturbed in the mother. The fetus is separated from the mother by three layers of tissue. Nutrients and waste are delivered and eliminated through diffusion, rather than direct connection. This group includes equids, swine, and ruminants.

Endotheliochordal, which is slightly more invasive to the mother, only preserves the uterine epithelium. Nutrients and waste are not exchanged through direct connection to the mother, but the placenta only leaves one layer of tissue between it and the mother. This group includes cats and dogs.

Hemochorial is the most invasive form of placenta in the animal kingdom. The embryo directly hooks itself up to the host (mother’s) blood flow, and leaves no tissue layers between the female and the placenta. This allows much more efficient nutrient transfer to the embryo or fetus, but is also potentially the most harmful to the female since the embryo attaches itself so securely to the uterine wall. The female must develop preemptive measures (a thickened uterine lining) to protect herself from a life-form that is literally driven to take all of the nutrients it needs to develop, and which has adapted to connect itself directly to the host. This group includes elephant shrews, most bats, and most primates.

Interested in more about the science behind reproduction and how amazingly efficient the human embryo is at sucking its host clean, just to obtain its needed resources for development?

PZ Meyers at Pharyngula has an understandable explanation of the article I referenced for this post.

There is also a great site by R. Bowen about the pathophysiology of the reproductive system.

An American Text-Book of Obstetrics for Practitioners and Students. Edited by Richard C. Norris, 1895.

medicalschool: Embryology of the Diaphragm

Tue, 07 May 2013 19:08:59 +0100

medicalschool:

Embryology of the Diaphragm

the-science-llama: Bat Embryos The first image are embryos of...

Sat, 06 Apr 2013 22:17:04 +0100

the-science-llama:

Bat Embryos

The first image are embryos of the species Molossus rufus, the black mastiff bat. These images formed part of an embryonic staging system for this species. — By Dorit Hockman

The second image shows a bat embryo developing from 18 weeks to 24

biocanvas: Epithelial cells line surfaces and cavities...

Sun, 31 Mar 2013 22:02:01 +0100

biocanvas:

Epithelial cells line surfaces and cavities throughout the body, forming skin, glands, and tracts. This mouse embryo has been genetically engineered to allow for the visualization of epithelial cells, showing the pattern of whisker placement on the face.

Image by Evan Heller, Rockefeller University.

ohyeahdevelopmentalbiology: micro-universe: A chicken embryo...

Wed, 27 Mar 2013 13:50:35 +0000

ohyeahdevelopmentalbiology:

micro-universe:

A chicken embryo inside of an egg. By the 72 hour stage the heart is well developed and the somites, optic vesicle, tail and leg buds are visible. Fractal networks of blood vessels bring energy from the yolk and exchange carbon dioxide with oxygen in the allantois.

sciencenote: Embryonic Rat Thoracic Aorta Medial Layer Myoblast...

Wed, 06 Feb 2013 16:42:32 +0000

sciencenote:

Embryonic Rat Thoracic Aorta Medial Layer Myoblast Cells (A-10 Line)

A culture of adherent A-10 rat thoracic aorta cells was fluorescently triple-labeled with MitoTracker Red CMXRos, Alexa Fluor 350 conjugated to phalloidin, and SYTOX Green, targeting the mitochondria, filamentous actin network, and nuclei, respectively. In this image, the bright red mitochondrial network is superimposed on a deep blue actin cytoskeletal framework centered around the green nuclei.

scientificillustration: Evolutionary Perspectives on Pregnancy...

Tue, 29 Jan 2013 14:02:56 +0000

scientificillustration:

Evolutionary Perspectives on Pregnancy by John C. Avise

“Covering both the internal and external incubation of offspring, this book provides a biology-rich survey of the natural history, ecology, genetics, and evolution of pregnancy-like phenomena. From mammals and other live-bearing organisms to viviparous reptiles, male-pregnant fishes, larval-brooding worms, crabs, sea cucumbers, and corals, the world’s various species display pregnancy and other forms of parental devotion in surprisingly multifaceted ways. An adult female (or male) can incubate its offspring in a womb, stomach, mouth, vocal sac, gill chamber, epithelial pouch, backpack, leg pocket, nest, or an encasing of embryos, and by studying these diverse examples from a comparative vantage point, the ecological and evolutionary-genetic outcomes of different reproductive models become fascinatingly clear.

John C. Avise discusses each mode of pregnancy and the decipherable genetic signatures it has left on the reproductive structures, physiologies, and innate sexual behaviors of extant species. By considering the many biological aspects of gestation from different evolutionary angles, Avise offers captivating new insights into the significance of “heavy” parental investment in progeny.”

Quadruple helix' DNA discovered in human cells

Thu, 24 Jan 2013 19:43:17 +0000

Quadruple helix' DNA discovered in human cells:

In 1953, Cambridge researchers Watson and Crick published a paper describing the interweaving ‘double helix’ DNA structure - the chemical code for all life. Now, in the year of that scientific landmark’s 60th Anniversary, Cambridge researchers have published a paper proving that four-stranded ‘quadruple helix’ DNA structures - known as G-quadruplexes - also exist within the human genome. They form in regions of DNA that are rich in the building block guanine, usually abbreviated to ‘G’.

The findings mark the culmination of over 10 years investigation by scientists to show these complex structures in vivo - in living human cells - working from the hypothetical, through computational modelling to synthetic lab experiments and finally the identification in human cancer cells using fluorescent biomarkers.

Read more at: http://phys.org/news/2013-01-quadruple-helix-dna-human-cells.html#jCp

biocanvas: The pectoral fin of an embryonic Chiloscyllium...

Sat, 19 Jan 2013 09:52:00 +0000

biocanvas:

The pectoral fin of an embryonic Chiloscyllium plagiosum, the whitespotted bamboo shark.

Image by Dr. Andrew Gillis, University of Cambridge.

jtotheizzoe: Every Embryo In the neighborhood of 600 million...

Wed, 16 Jan 2013 16:55:38 +0000

jtotheizzoe:

Every Embryo

In the neighborhood of 600 million years ago, the embryos of the animal kingdom branched into several distinct arms based on how that little ball of cells that’s created after fertilization begins to pattern and fold itself into what will one day become a fully grown adult.

Think about this: If you go far enough back in evolution, the common ancestors of all of these various families of organisms, from vertebrates to insects to sea slugs, had the same set of genes to call upon in order to make a three-dimensional animal. Very quickly, and quite beautifully, the diversity of life’s forms exploded.

Much of the amazing variety you see among animals today begins with the patterns laid down in the earliest stages of development, and this represents the crossroads where they all began their journey to the modern age.

(From Wired’s Best Scientific Figures of 2012)

micro-scopic: This movie shows the “yolk flash”. The apparently...

Fri, 11 Jan 2013 09:10:29 +0000

micro-scopic:

This movie shows the “yolk flash”. The apparently whole-embryo calcium pulse appears to initiate over a widespread area of blastoderm, possibly earliest at the animal pole, and then spreads first to the yolk cell membrane and then along the ventral midline heading rostrally. 30-sec integration window moving in 5-sec steps, elapsed real time of 340 sec played at 50x real time.. Fertilized zebrafish eggs were collected within 5 min of spawning, enzymatically dechorionated, and injected with approximately 0.9 nl of a 1% solution of recombinant f-aequorin in 100 mM KCl, 5 mM Mops, and 50 μM EDTA. During imaging the embryos were maintained at 28°C in 30% Danieau’s medium containing penicillin (0.5 mg/ml), streptomycin (5,000 units/ml; Sigma), and 0.5% methylcellulose. Imaging was performed on a Photon Imaging Microscope (Science Wares, Falmouth, MA) that used a photon-counting spatial detector with a resistive anode output (Photek, St. Albens-on-Sea, U.K.). Digitized detector output in the form of a stream of time-labeled eight-bit x—y coordinates (256 × 256 pixels) was used to construct time-lapse imaging sequences. The imaging system software allowed the original photon data stream to be analyzed according to any chosen integration time, with the resulting image frames maintaining accurate photon quantitation up to 256 photons per pixel. These images are part of an image series within the Zebrafish—The Living Laboratory CD made available by Mark Cooper and described in Methods in Cell Biology Volume 77, 2004, Pages 439-457. Corresponds to supplemental video in PNAS January 5, 1999 vol. 96: 157-161 and quantification of color scale shown in Fig 1.

Source 1. Source 2.

Turing model for embryonic development of fingers and toes confirmed

Mon, 24 Dec 2012 11:53:34 +0000

Turing model for embryonic development of fingers and toes confirmed:

ohyeahdevelopmentalbiology:

sciencebriefs:

Scientists have identified the mechanism responsible for generating our fingers and toes, and revealed the importance of gene regulation in the transition of fins to limbs during evolution. By combining genetic studies with mathematical modeling, the scientists provided experimental evidence supporting a theoretical model for pattern formation known as the Turing mechanism. In 1952, mathematician Alan Turing proposed mathematical equations for pattern formation, which describes how two uniformly-distributed substances, an activator and a repressor, trigger the formation of complex shapes and structures from initially-equivalent cells.

“The Turing model for pattern formation has long been debated, mostly due to the lack of experimental data supporting it,” explained Rushikesh Sheth, co-first author of the study. “By studying the role of Hox genes during limb development, we were able to show, for the first time, that the patterning process that generates our fingers and toes relies on a Turing-like mechanism.”

In humans, as in other mammals, the embryo’s development is controlled, in part, by Hox genes. These genes are essential to the proper positioning of the body’s architecture, and define the nature and function of cells that form organs and skeletal elements.

“Our genetic study suggested that Hox genes act as modulators of a Turing-like mechanism, which was further supported by mathematical tests,” added Marie Kmita, one of the team leaders. “Moreover, we showed that drastically reducing the dose of Hox genes in mice transforms fingers into structures reminiscent of the extremities of fish fins. These findings further support the key role of Hox genes in the transition of fins to limbs during evolution, one of the most important anatomical innovations associated with the transition from aquatic to terrestrial life.”

I have a special place in my heart for all things Turing as he was the subject of my final year dissertation.

jtotheizzoe: Every Embryo In the neighborhood of 600 million...

Sun, 09 Dec 2012 22:42:11 +0000

jtotheizzoe:

Every Embryo

In the neighborhood of 600 million years ago, the embryos of the animal kingdom branched into several distinct arms based on how that little ball of cells that’s created after fertilization begins to pattern and fold itself into what will one day become a fully grown adult.

Think about this: If you go far enough back in evolution, the common ancestors of all of these various families of organisms, from vertebrates to insects to sea slugs, had the same set of genes to call upon in order to make a three-dimensional animal. Very quickly, and quite beautifully, the diversity of life’s forms exploded.

Much of the amazing variety you see among animals today begins with the patterns laid down in the earliest stages of development, and this represents the crossroads where they all began their journey to the modern age.

(From Wired’s Best Scientific Figures of 2012)

mordicant: 5 week old human embryo versus 5 week old dolphin...

Sun, 02 Dec 2012 00:25:14 +0000

mordicant:

5 week old human embryo versus 5 week old dolphin embryo

gearbot: Chick embryos at various stages of development.

Sun, 02 Dec 2012 00:25:07 +0000

gearbot:

Chick embryos at various stages of development.

skeptv: Scientists Learn to Unlock the Destiny of a...

Fri, 30 Nov 2012 18:44:03 +0000

skeptv:

Scientists Learn to Unlock the Destiny of a Cell

Breaking a biological signaling system in an embryo allows scientists to change the destiny of a cell. The findings could lead to new ways of making replacement organs.

by Futurity.org.

medicalschool: Face Development in the Womb Michael Mosley...

Sun, 18 Nov 2012 23:47:15 +0000

medicalschool:

Face Development in the Womb

Michael Mosley talks about face development with extraordinary CGI produced especially for episode one of Inside the Human Body.

biocanvas: An early developing embryo, known as a blastula, of...

Sun, 18 Nov 2012 23:30:46 +0000

biocanvas:

An early developing embryo, known as a blastula, of Dendraster excentricus, the sand dollar. Apparatuses aiding in cell division, such as mitotic spindles and asters, can be seen.

Image by by George von Dassow, University of Oregon.

ohyeahdevelopmentalbiology: frontal-cortex: Starfish...

Sun, 18 Nov 2012 23:29:57 +0000

ohyeahdevelopmentalbiology:

frontal-cortex:

Starfish development

Seven successive stages of earlier starfish development, precursors of the juvenile shown above. Increasing in age from left to right and top to bottom. The first three specimens are embryos, and the last three are larvae, with the fourth being transitional between the two. Many tube feet are visible in the oldest specimen (lower right).

Composite image. Reflected light, stereomicroscope. The image is quite incredible looking when viewed in full, IMO.

by Sharon Minsuk