Chiaroscuro

A pair of Short-Tailed Opossum (Monodelphis domestica), 14 days postnatal.  Note the presence of hairs and whiskers on the face as well as the bones ossifying in the fore and hindfeet.  Image credit: Curious Sengi.

Greetings, fellow Snurflers!

We have now entered that season during the academic year when many of us are facing great hurdles:  qualifying exams and dissertation defenses.  I will be presenting my research proposal at quals in a few weeks and I wanted to share some of the images from my work with you.

My research on the evolutionary origin and subsequent modifications of facial muscles in mammals involves a lot of comparative morphology:  looking at a wide range of animals (including non-mammals) to piece together a picture of what is old and what is novel, ancestral and derived, conserved and innovative, and what is just plain weird.  I am using techniques and ideas from developmental biology to show the spatiotemporal sequence of how facial muscles grow and differentiate in different embryos, but to also shed light on some key processes behind the question of why muscles grow over the faces of mammals, but not in animals like reptiles.

At the moment, I am working a lot with the embryos and neonates of the Brazilian Short-Tailed Opossum (Monodelphis domestica), a marsupial that is increasingly being used as a model organism in laboratories.  The images here are of young opossums, collected 14 days after birth.  Like all other marsupials, gestation time is short and the babies are born in an extremely underdeveloped state where they are essentially all just forelimbs and a mouth.  Now a few weeks after birth, these little guys are starting to look much more like recognizable animals.

These photographs were taken after the specimens were bleached into a ghostly white.  There are more steps ahead before we can visualize the development of facial muscles.  See what happens next in our following posts!

Image credit: Curious Sengi.