Drosophila. . . . Drosophila

Poor little fruit fly

Lives a mere fourteen days unless

I choose thee to kill

(A Haiku by me on Drosophila melanogaster)

So here we are, blogging again even those I hoped to never have to actually us this page for academic purposes again, but as life would have it, Here I am again.

So the model organism I have chosen is Drosophila melanogaster.

What type  of cell am I?

I am a sensory neuron (or afferent neuron) and I belong to the peripheral nervous system of my organism. I am an important cell type for the survival of the fruit fly (whatever that means to the organism, I mean, how do they view time? Is it as seen in the movie Epic where humans are seen as large slow bumbling fools? How long does this few week life span actually seem to them? Ah, I digress; this is what stems from watching too much Doctor Who. I apologise).

So, a sensory neuron like any other cell of this organism starts life as a humble undifferentiated cell found in the embryo. This embryo undergoes roughly 13 cell divisions before things start getting complicated. The syncytial blastoderm is the insect embryo. This holds all the replicate nuclei in a single common cytoplasm before cleavage and specialisation.It is from this that the sensory neuron develops..

We begin our specialisation at stage 13, and we quickly develop our receptors and accessory cells that allow us to detect stimuli. By the end of stage 17 of embryonic development, we are fully formed and the embryo now proceeds to the development of the rest of the larval body.

Sensory neurons are bipolar ( has two extensions) or multipolar (meaning that they have many dendrites to associate with sensory organs but still have just one axon).  The cell body which houses the nucleus and all other organelles is found to middle of the sensory neuron.

 

Sensory neurons can be bipolar or multipolar

 

There are 15 sensory neurons that are multidendritic and are classed as dendritic arborization (da) neurons. The are classed from I-V based on the size of their receptive fields and complexity at the mature larval stage. Five of the six da neurons found in a particular segment of adult Drosophila were found to be those that persisted from the larval stage.

The sensory neurons of Drosophila m. are associated with the sense organs and the receptors and carry information to the CNS. These receptors can be found in the thorax where  six pairs of thoracic ganglia (a ganglion is a dense cluster of connected neurons that process sensory information and motor responses) control the leg and wing movement. Sensory neuron’s associated with the abdominal muscles help with control of those muscles while those found on the insects back end help with the control of the fly’s genitalia and anus.

FBim0000091

The 13th cell cycle when the sensory neurons start to differentiate

FBim0000114

After the 17th cell cycle, the sensory neurons are fully developed

 

The various ganglia that the sensory rectors and thus the sensory neurons are associated with.

 

More in-depth formation of the peripheral nervous system

References and Further reading:

http://flybase.org/.bin/fbimage?FBdv:00005289|FBbt:00000137

http://groups.molbiosci.northwestern.edu/holmgren/Glossary/Definitions/Def-S/syncytial_blastoderm.html

http://www.sdbonline.org/fly/atlas/12-13pns.htm

https://dgrc.cgb.indiana.edu/cells/store/catalog.html

http://honorsbiologyp6.wikispaces.com/P6+Insects+Sensory+Systems

http://www.cals.ncsu.edu/course/ent425/tutorial/nerves.html

http://www.neuraldevelopment.com/content/4/1/37

http://www.ivy-rose.co.uk/HumanBody/Nerves/Neurons.php

 

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