The start of Veterinary Embryology… (Day 218)

Histology of the eye section of the retina

Today’s Diary Entry is sponsored by Pets Bureau

For those that don’t know what embryology is; it is the growth of an animal after fertilisation of an egg (ovum) by sperm (or in the case of some species self-fertilisation). The sperm and egg fuse together with the haploid DNA contained in each combining to form diploid DNA within the nucleus. This single cell the goes on to rapidly divide multiple times with the number of cells doubling with each division (2-4-8-16 etc). Talking simply, this then folds in on itself (invaginates) to form a tube through the middle which will later become the digestive system. At this stage 3 different layers are formed; the ectoderm which is the outer later, the mesoderm which is the middle layer and the internal layer which is the endoderm. The cells in each of these layers are then differentiated to form different organs and structures related to that part of the body – for example the ectoderm forms the majority of the skin.

After embryology we then had the histology lecture that we had missed previously on the senses and today looked at the eye and ear. Personally I think the eye is amazing as the cells here are some of the fastest replicating cells within the body – most injuries to the surface layer heal within hours! The retina is the part of the back of the eye that is responsible for processing images into nerve pulses for the brain to understand and under the microscope looks like this…

Histology of the eye section of the retina

Looking at it quickly the layer at the top which is thick forms the fibres that holds the eye together known as the choroid and is attached to the sclera. Under this we then have a layer of pigment before the layer of rods and cones with the associated ganglionic nerve structures.

We finished this afternoon with our Physiology lecture which was looking at the brain, this is something so complex that by the end of the lecture most of use had our head aches. As vets we need to understand how different signals are processed, and the areas of the brain that deal with different functions of the body. In fact if we wanted we could actually progress to become Veterinary Neurosurgeons…. Is that cool or what?!?!