Dr. Stephen Tobe's Virtual Laboratory

Diploptera punctata Dissection

Corpora allata

The corpora allata (CA) are a pair of endocrine glands situated below the brain that produce juvenile hormone. For biochemical assays, it is often useful to quantify how much JH is being produced, so it is necessary to dissect out the corpora allata.

Step 1

Place the cockroach ventral side down on a dissecting dish. Secure the abdomen and antennae with Plasticine .

Step 2

Cut open the pronotum with dissecting scissors. Place a drop of cockroach saline solution in the cavity to see the organs better.

Step 3

Remove the yellow sclerite with forceps. It is positioned dorsally above the corpora allata (CA).

Step 4

Some tissue will need to be removed to expose the CA. Slowly remove the tracheae, taking care not to puncture the gut.

Step 5

Pull back gently on the foregut to expose the paired CA.

Step 6

Remove the CA and place them in saline, and prepare for further experimentation. Note that in this case, the corpus allatum on the right has been damaged by some clumsy forceps work!

Brain

The brain of the cockroach is relatively easy to dissect. The head is cut from the body and fixed into plasticine. The top of the head is then removed with scissors. With care, it is then possible to remove surrounding tissues to expose the brain.

The brain of the cockroach Leucophaea maderae. Original image by Thomas Reischig.