Tag Archives: development

In the Womb: Alive and Kicking

For a pregnant woman, it can be a thrilling moment when her baby kicks for the first time. Women have described the feeling as a flutter, a tumble, or a gentle thud. However, these movements are not only exciting because they are unpredictable but because they indicate healthy fetal development. 

Although a pregnant woman may not feel her baby’s kicks and punches until 18 to 25 weeks of pregnancy, fetal movement may begin as early as seven weeks and science shows that it is crucial in the development of joints and bones. In fact, a lack of fetal movement can be a sign of abnormal musculoskeletal development and other poor birth outcomes. In the last decade, scientists have begun to wonder how mechanical factors have positive or negative effects on a baby in utero. 

MRI scan animation of developing fetuses
An animation composes of MRI scans of fetal movement during various stages of development. (Image: © Stefaan W. Verbruggen, et al./Journal of the Royal Society)

In particular, researchers Stefaan Verbruggen and Niamh Nowlan at Imperial College in London decided to take a deeper look at the mechanics of these fetal movements through several different studies. As it turns out, neonates can throw a pretty strong punch. In one experiment, researchers saw that fetal kicks can incur an impact of 6 lbs at 20 weeks, 10 lbs at 30 weeks, and less than 4 lbs beyond 30 weeks of pregnancy. The force of fetal kicks decrease after 30 weeks due to the limited amount of space for the baby to move. 

In addition, the force of fetal kicking was also observed in three different neonatal positions: typical (head-first), breech (feet first), and twin fetuses. These studies revealed that twin fetuses can exert the same amount of kick force and motion as a healthy singleton fetus in the typical head-first position. However, fetuses in the breech position showed significantly lower kick forces and lower stress and strain in their hip and knee joints. This discovery might explain why babies in the breech position have the highest probability of being born with hip problems.

simulated strain concentrations in a fetal leg
Simulation of principal strain which indicates that strain increases with gestational age for fetuses in the head first position.  Modified from Verbruggen et al., 2018.

 In another study, three mothers volunteered to have their wombs monitored via MRI so that the researchers could observe the geometry, force, and frequency of fetal motion. It was found that fetal muscles are able to produce nearly 40 times more force than the kick itself. The magnitude of force exerted by these muscles confirms the importance of fetal kicks for proper growth of the hip and knee joints. This information is helping scientists and doctors connect the dots between neonatal environment and newborn joint abnormalities.

Interested in learning more? Check out some of the new technology being developed to further this study!

The Mystery Behind the ‘Folded’ Brain

 

Picture of a walnut which has a strong similarity to a human cerebral cortex
Image by Ulrike Leone from Pixabay

Have you ever wondered why one of the most mysterious organ in our body, the brain, has a distinctive shape which has a strong resemblance to a walnut? Or, what are the major factors that could play a significant role in developing its particular shape, with crests and valleys, that wires our motions, senses, feelings and thoughts, which makes each one of us a unique human being?

Brain cortex of 34 different species which indicates relative size and foldedness
From Heuer, K. et al., Cortex 2019 High-res version: https://doi.org/10.5281/zenodo.2538751

For almost a century, the researchers from various different disciplines such as, neurology, engineering, evolutionary biology and applied mathematics have tried to solve the enigma behind the convoluted nature of the cortex, i.e. the outermost layer of the brain. Although the degree of convolution has shown to vary proportionally with the size of the brain among different species, as was shown in a recent study, this (un-)foldedness trait can not be attributed to the size of brain only, while some of the human brain disorders, such as epilepsy, might include the smooth brain aspect,  i.e. lissencephaly.

Interestingly, the human brain is not always folded throughout its stay in the womb. The gyrification (development of gyri and sulci, the two characteristics of the cerebral folding) begins only after the mid-gestation (sixth month of fetal life) and further continues to develop postnatally until adulthood. This remarkable phenomena of the brain has lead the researchers from the University of Jyvaskyla, Harvard and Aix-Marseille to collaborate and startlingly they had been able to replicate this unique behavior of the brain on 3D-printed soft composite layered gel samples using smooth fetal brain morphology obtained from magnetic resonance images (MRI) as a starting point. According to the first co-author Dr. Tallinen from their original research paper which is published in Nature Physics in 2016, when this composite layered gel is submerged in a jar of solvent called Hexanes at room temperature for 20-30 minutes,  the differential swelling of the outer layer of the gel is observed, and this leads to the formation of sulci and gyri which is similar in morphology to the cortex of the brain and occurs in a similar relative time frame that is observed in real fetal brain development. Another great article written on this study is also published in TheHarvardGazette!

The theory behind this naturally and experimentally observed cortical patterning can be explained by mechanical principles, and is a result of the mechanical instability generated by constrained cortical expansion due to growth. The computer simulations of gyri and sulci formation which was performed by researchers from Stanford University on 2015 further support this mechanistic perspective such that the mechanical environment and neuronal growth rate on preferred orientations plays a crucial role in controlling the gyral and sulcal pattern formation. Axons or the nerve fibers, which are the transmission cables of our nervous system, tend to respond to mechanical stretch during growth by dynamically adjusting their length, which ultimately serves as a regulator for cortical folding.

Interested in reading more on why our brains are folded? Check out these impressive articles from LiveScience and McGovernMIT!

Also check out this cool TED video from Prof. Suzana Herculano-Houzel here!

Canine Hip Dysplasia: What You Should Know

Canine hip dysplasia (CHD) is a degenerative hip disease that tends to develop in large breed dogs, such as the Bernese Mountain Dog, affectionately referred to as Berners. CHD significantly decreases the quality of life of a dog and often leads to complete immobility if left untreated. Experts estimate that about 28% of Berners are affected by dysplastic hips, making them the 8th most susceptible dog breed.

Bernese mountain dog with superimposed image of hip ball and socket joint.
Image from Packerland Veterinary Clinic.

At birth, puppy skeletal structures are largely composed of cartilage that is much softer than bone. This softer cartilage is able to adapt much more easily to the rapid growth that occurs during the early months of a dog’s life. In their first few months, Berners will typically gain 2-4 pounds per week, which adds increasingly large stresses to their developing bones and joints. While genetics play a large role in the susceptibility of a dog to develop CHD, the loading cycles and forces on the cartilage greatly shape the development of the dog’s hip.

Correctly formed hip versus a deformed femur head and shallow hip socket.
Image from Dog Breed Health.

The hip is a ball and socket joint, where the head of the femur, the very top of the dog’s leg, should fit perfectly into a socket in the pelvis. If the ligaments that hold the femur in the hip socket are too weak or damaged at all, the positioning of the

Evenly distributed forces on a correctly developed hip joint versus force concentration acting on a dysplastic hip joint.
Modified from The Institute of Canine Biology.

hip joint will be off and the hip will be subjected to unbalanced forces and stresses over the course of the dog’s life. The distribution of forces experienced by the hip joint in normal hips is evenly spread, while dysplastic hips are subjected to a stress concentration on the tip of the femur. These unnatural forces will cause laxity in the hip joint, leading to instability, pain, and often times the development of osteoarthritis.

 

There are also a number of environmental factors, many of which are inherent to large dog breeds, that dramatically increase a dog’s susceptibility to CHD. A study by Dr. Wayne Riser concluded that factors such as oversized head and feet, stocky body type with thick, loose skin, early rapid growth, poor gait coordination, and tendency of indulgent appetite all contributed to the development of CHD. All of these features are generally inherent to large breed dogs, such as Berners, so great care must be taken in order to mitigate their effects on the quality of life for these dogs.

Multiple studies have shown that treatment that is implemented early in the dog’s life is much more effective than late-in-life treatments. CHD warning signs can be seen in puppies as young as 4 months old, and most veterinary professionals agree that if scans occur at 2 years of age, the most optimal time for treatment has passed. Since larger stresses will be put on the hip joint as the dog grows, surgical repairs, or changes in diet and exercise, are most effective if implemented before the dog’s skeletal frame is completely developed.

 

timeline of canine hip dysplasia development
Modified from The Institute of Canine Biology

Additional information regarding this topic can be found at The US National Library of Medicine or The Journal of Veterinary Pathology.