Animal Tissue Test - 5

Female cockroaches have a brood pouch and short antennae. Brood pouch in females is formed from the fusion of 7^th, 8^th and 9^th sterna.

Earthworms have a tube-like arrangement or cylindrical shaped and reddish-brown segmented body. The body consists of S-shaped setae, which help in locomotion in the earthworm. Setae are present in each segment except in the first, last and clitellum segments (around the 14^th, 15^th and 16^th segments).

Tight junctions help to stop substances from leaking across a tissue. These junctions are required between the cells of bile ducts.

Ciliated epithelium is present in the lining of the inner surface of bronchioles that functions in moving particles or mucus in a specific direction over the epithelium.

The body of the earthworm is covered externally by a thin noncellular cuticle. This is followed by an epidermal layer, two muscle layers, and inner coelomic epithelium. The epidermis has columnar epithelial cells, which are present in a single layer. There are also some secretory gland cells present.

The nervous system of a cockroach is spread throughout the body. Thus, even if the head is severed off, it will still live for as long as one week. In addition to this, cockroach breathes through every segment of its body except the head, so decapitation does not deprive it of oxygen.

External ear (pinnae) is absent in frogs and only tympanum can be seen externally.
In frogs and toads, the tympanum is a large external oval shape membrane made up of nonglandular skin. It is located just behind the eye. It does not process sound waves; it simply transmits them to the inner parts of the amphibian's ear, which is protected from the entry of water and other foreign objects.

Pharyngeal nephridia lie in three paired tufts, one on either side of the anterior region of the alimentary canal in the segments 4^th, 5^th and 6^th. The tufts of pharyngeal nephridia also contain blood glands. Each pharyngeal nephridium is about the size of a septal nephridium but it is of the closed type having no funnel or nephrostome. It has a short straight lobe and a spirally twisted loop. Ductules arise from each nephridium and unite to form a single thick- walled duct on each side in each segment.

In cockroaches, a mushroom shaped gland or utricular gland functions as an accessory reproductive gland. It is present in 6^th to 7^th abdominal segments. It is whitish in colour and situated at the junction of vasa deferentia with the ejaculatory duct.

Intercalated discs are found in cardiac cells. They are communication junctions at some fusion points that allow the cells to contract as a unit.