Insect Dissection Lab (III)

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Dissection of cockroach nervous system Ventral nerve cord and ganglia Insect Physiology (Ento 306) Remove the wings by cutting their attachments with a pair of scissors. The dissection is facilitated if the legs are removed by cutting across their trochanters. Insert the blade of a pair of fine scissors in the lateral margin of the body between the tergite and sternite. Insert the blade only as deep as is necessary to penetrate the exoskeleton and be careful you do not damage internal organs with deep cuts. Cut anteriorly along the right side of the tergites all the way to the anterior end of the pronotum. Cut transversely across the anterior margin of the pronotum, just posterior to the head, and upon reaching the left side, change directions and cut posteriorly along the left side all the way back to the last tergite. Make a transverse cut through the exoskeleton across the posterior border of the last tergite. You have now cut all of the way around the dorsum. Remove the dorsal diaphragm along with the tergal muscles, tracheae, and heart from the abdomen. Accomplish this by cutting with fine scissors around the periphery of the abdomen. Remove the gut, fat body, reproductive organs from the thorax and abdomen. Remove the longitudinal body wall muscles (sternal muscles) and connective tissue as necessary from the floor of the abdominal cavity to reveal the ventral nerve cord. Identify and draw one of the three thoracic ganglia. From each extend several pairs of nerves to the abundant muscles of these segments. Cockroach brain Using your scissors and forceps or a razor blade carefully remove the epicranium (top of the head) from the region between the compound eyes and antennae. Remove muscles as necessary to reveal the bright white, dorsal brain between the compound eyes. Draw the cockroach brain in as much detail as possible. Label at least two of the following features: -‐ Optic lobe -‐ Protocerebrum -‐ Deutocerebrum -‐ Tritocerebrum -‐ Corpora cardiac -‐ Corpora allata -‐ Circumesophogeal connective
Dissection of Tobacco hornworm caterpillar External features Insect Physiology (Ento 306) Manipulate the caterpillar so you are able to draw it in an en face position. Draw what you see and label the following features using the stereo dissecting microscope: -‐ Labrum -‐ Mandibles -‐ Maxilla/maxillary palp -‐ Spinneret (for producing silk) -‐ Antennae -‐ Ommatidia -‐ Legs Identify the following structures involved in walking on the caterpillar -‐ Proleg -‐ Anal proleg/Anal clasper Identify and draw a spiracle Caterpillar hemocoel dissection Cut off the caudal horn at its base. Insert scissors into the hole from the cut-‐off horn and cut through skin and body muscle along a line down the center of the caterpillar’s dorsal side. Cut from caudal to rostral (head) end. Pull open the exoskeleton and use dissection pins to hold the exoskeleton and body muscles open by pinning through the body wall at an outward angle. Bathe the caterpillar in saline solution. Identify the gastrointestinal tract, fat body, and trachea. Gastro-‐intestinal tract Use forceps to tear the esophagus and lift out the digestive track carefully. Identify the following features -‐ Crop/midgut -‐ Malphigian tubules -‐ Proctodeal valve -‐ Intestine -‐ Rectum
Page 1: Name:______________________ Insect
Page 5 and 6: Dissection illustration sheets Desc
Page 7 and 8: Description: Magnification: Descrip
Page 9 and 10: Insect Physiology (Ento 306) Dissec
Page 11 and 12: Insect Physiology (Ento 306) Dorsal

Insect Dissection Lab (III)

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