Glandular Epithelium. Some of the columnar or cuboidal cells get specialised for secretion and are called glandular epithelium. They are mainly of two types:
(i) Unicellular, consisting of isolated glandular cells (goblet cells of the alimentary canal),
(ii) Multicellular, consisting of cluster of cells (salivary gland).
On the basis of the mode of pouring of their secretions, glands are divided into two categories namely exocrine and endocrine glands. Exocrine glands secrete mucus, saliva, earwax, oil, milk, digestive enzymes and other cell products. These products are released through ducts or tubes. In contrast, endocrine glands do not have ducts. Their products, called hormones, are secreted directly into the fluid bathing the gland.

All cells are held together with intercellular material. These materials form junctions between cells.
There are three types of cell junctions found in epithelial tissue.
(a) Tight Junctions: These junctions help in stopping leakage of substances across a tissue.
(b) Adhering Junctions: These junctions keep neighbouring cells together.
(c) Gap Junctions: These junctions connect cytoplasm of adhering cells, and facilitate exchange of materials.

Nervous System of Cockroach:
(i) The nervous system of cockroach consists of a series of fused, segmentally arranged ganglia joined by paired longitudinal connectives on the ventral side.
(ii) Three ganglia lie in the thorax, and six in the abdomen. The nervous system of cockroach is spread throughout the body.
(iii) The head holds a bit of a nervous system while the rest is situated along the ventral (belly-side) part of its body.

Fertilization and Development in Pheretima:
(i) A mutual exchange of sperm occurs between two worms during mating. One worm has to find another worm and they mate juxtaposing opposite gonadal openings exchanging packets of sperms called spermatophores.
(ii) Mature sperm and egg cells and nutritive fluid are deposited in cocoons produced by the gland cells of clitellum. Fertilisation and development occur within the cocoons which are deposited in soil.
(iii) The cocoon holds the worm embryos. After about 3 weeks, each cocoon produces two to twenty baby worms with an average of four.
(iv) Earthworms development is direct, i.e., there is no larva formed.

Blood Vascular System. Pheretima exhibits a closed type of blood vascular system, consisting of blood vessels, capillaries and heart. Due to closed circulatory system, blood is confined to the heart and blood vessels. Contractions keep blood circulating in one direction. Smaller blood vessels supply the gut, nerve cord, and the body wall. Blood glands are present on the 4th, 5th and 6th segments. They produce blood cells and haemoglobin which is dissolved in blood plasma. Blood cells are phagocytic in nature. Earthworms lack specialised breathing devices. Respiratory exchange occurs through moist body surface into their blood stream.

Difference between blood plasma and serum.

Difference between keratinised and non keretinised  stratified squamous epitheila

In cockroach, there are two types of eyes, i.e., apair of simple eye and a pair of compound eyes. A compound eye has upto 2000 hexagonbal units called ommatidia. These are responsible for producing mosaic vision. The adjacent ommatidia are separated internally by the pigment cells. An ommatidium has two parts 
(i) Outer dioptoric or focussing part, which consisits of a corneal lens, two corneagen cells, a crystalline cone and four cone cells or vitrellae.
(ii) Inner receptive part has a spindle-shaped pigment contaning rhadome surrounded by eight retinulae which continue as nerve fibre.

Similarities between cardiac and skeletal muscles The cardiac and skeletal muscles both are made up of elongated fibres, which have numerous myofibrils. The myofibrils of the cardiac muscles have the same structure as those of skeletal muscle and are made up of actin and myosin filaments. The cardiac and skeletal muscles fibres have dark and light bands.

Malphighian tubules are the amin excretory organs of cockroach.

The body cavity of cockroach is filled with haemolymph so, it is called haemocoel. Cuticle, epidermis and basement membrane are layer of body wall in cockroach.