Cockraoch Temporary Preparation (Chart and Theory)

Compound Eyes of Cockroach:  

Location : 

The eyes of cockroach are large, black, kidney-shaped structures situated dorso-laterally on the head. 

Structure : 

Each eye is composed of about 2,000 similar hexagoal units, called as ommatidia. Each ommatidium capable of forming  image, hence, called compound eyes.  Each ommatidium consists of two parts:- diopteric and receptive.

 

A.Diopteric Part: 

It gathers and focusses the light rays. It consists of corneal lens secreted by corneagen cells and vitrellae or cone cells which forms a hard crystalline cone or lens.

B. Receptive Part: 
It receives the image cells or retinulae and rhadomere forming long refractive rod, the rhabdome. 

Function of eye:
An apposition or mosaic image is formed in cockroach.

Walking leg of Cockroach 

In cockroach there are presence of three pair of walking leg.

Location : According to basis of attachment with thorax they are called as pro-thoracic, meo-thoracic and meta-thoracic  legs. 

Structure :Each leg consists of following parts.

1.     Coxa

2.     Trochanter

3.     Femure

4.     Tibia

5.     Tarsus

1.     Coxa : It is large basal part of leg articulate with thorax segment.

2.     Trochanter: It is small, freely moving part of leg.

3.     Femur : It  is long, broad and stout  part of leg of cockroach.

4.     Tibia : It is long, slender, and uniformly thick part of leg. Tibia shows presence of stout bristles.

5.     Tarsus : It last segment of leg consists of five movable joints or podomere. The podomere shows presence of adhesive pads, the platulae. The last podomere of tarsus have pair of claws. In between claws, soft and hollow pulvillus or arolium is present, act as adhesive organ for holding support on smooth surface.

Function: The legs of cockroach are adopted for locomotion, climbing  and running.  Cockroaches are able to fast running hence called cursorial.

Gizzard of Cockroach 

T. S. Of Gizzard of Cockroach

Location :Gizzard is rounded muscular structure lies between fore gut and mid gut. 

Structure :  The lumen of gizzard shows presence of 6 –chitenous teeth in anterior chamber and posterior part shows ring shaped fine hair-like bristles.

Functions of gizzard:

1.     The chitenous teeth helps in grinding of food material.

2.     The bristles are useful for straining or filter fine particle, entering into the mid-gut. Thus, bristles act as sieve.

Thoracic Spiracles of Cockroach 

In cockroach respiration is takes place through spiracles and trachea.

In cockroach there are  ten pairs of spiracles also called as stigmata.

Location : Out of ten pairs of spriacles, two pairs are present in the thorax and eight pairs of spiracles are present on abdomen.

Structure:

1.  Each spiracles has two parts i.e. cup like atrium covered by lid or operculum.

2.  The thoracic spiracles operculum is bi-lobed  while abdominal spiracles operculum is single, parrot beak like.

3.  Each spiracle has slit like aperture.  Opening and closing of spiracle is regulated by sphincter valves.

4.  Each spiracle is surrounded by bristles, preventing entry of dust particle into spiracles.

5.  The slit of spiracles leads into short chamber called atrium. 

6.  From atrium arises the tracheal tube which leads into tracheoles.

Function:

Inlet and outlet of air during respiration.

Trachea of Cockroach

The respiration in cockroach is takes place by trachea and trachioles.

Location: Trachea forms transverse and longitudinal network on dorsal, ventral and lateral side.

Structure : Each trachea is tube like structure made up of elastic material covered by chitinous spring-like lining called as intima. The intima prevents trachea from collapsing during respiration.

Function: inhalation and ex-halation of respiratory gases.

Salivary Gland of Cockroach:

Location : In cockroach a pair of salivary gland associated with alimentary canal lies in thoracic cavity on either side crop.
Structure: Each lobe of salivary gland shows two parts
1. Glandular part
2. Bag like reservoir.
From glandular part arise salivary duct which unite to form common salivary duct. The common salivary duct unites to form efferent salivary duct which runs anteriorly and opens at the base of hypo-pharynx in pre-oral cavity. The two ducts of reservoir join to form another common salivary duct.
Functions of salivary gland:

1.      Salivary gland is made of several lobules or acini produces saliva.

2.      Salivary reservoir stores saliva.