Structural Organisation in Animals Test 7

Basal Lamina: It is outer thin layer (near the epithelial cells), composed of muco­polysaccharides and glycoproteins, both secreted by epithelial cells. It is visible only with the electron microscope.

Fibrous or Reticular Lamina: It is inner thick layer, composed of collagen or reticular fibres of the underlying connective tissue. It is visible with light microscope. The basement membrane provides elastic support. It also allows selective chemical exchange between epithelial tissues and surrounding blood vessels.

Simple epitheliumIt is found generally on secretory and absorptive surfaces. It covers surfaces exposed to mechanical or chemical abrasions because it is not effective in protecting the underlying tissues. It is formed of a single layer of cells resting on the basement membrane.

Squamous epithelium: Squamous epithelium consists of cells, which are thin, flat and polygonal having a prominent round or oval nucleus. The cells have irregular boundaries that fit closely into those of neighbouring cells. Its main function is protection of the underlying tissues. It forms the inner lining of lung, alveoli, blood vessels and peritoneum of the body cavity.

A simple squamous epithelium is a single layer of flat cells in contact with the basal lamina (one of the two layers of the basement membrane) of the epithelium. This type of epithelium is often permeable and occurs where small molecules need to pass quickly through membranes via filtration or diffusion.

This epithelium is present in/the terminal bronchioles and alveoli of the lungs, walls of Bowman's capsules and descending limb of loop of Hen Ie. In the blood vessels and heart it is called endothelium. In coelom, it is called as mesothelium.

The ventricular system is a set of communicating cavities within the brain. These structures are responsible for the production, transport and removal of cerebrospinal fluid, which bathes the central nervous system.

The loop of Henle is the U-shaped portion of the nephron that leads from the proximal convoluted tubule to the distal convoluted tubule. The curved portion of Henle's loop is lined by squamous epithelium. The squamous epithelium enables rapid diffusion of blood and diffusion of small molecules.
So, the correct answer is 'Squamous epithelium'.

The trachea and bronchi are lined by stratified ciliated epithelium. The height of the epithelium decreases as the bronchial tree branches. Four different cell types can be found in the epithelium: basal cells, ciliated cells, goblet cells, and clear cells, which belong to the diffuse neuroendocrine system or amine precursor uptake and decarboxylation (APUD) system. 

The Germinal epithelium or epithelial cells are the ones present in the reproductive organs of animals, such as testis and ovary. These are the cells which divide and redivide itself to form the male and female gametes.

There is a structural difference between a kinocilium (which is a true cilium, having a 9+2 microtubule arrangement), and stereocilia (which don't have microtubules, instead they have actin cores).  

Pseudo-stratified epithelium : It is the simple columnar epithelium in which the regular arrangement of the cells is distorted. The cells of this type of epithelium are also twisted with respect to each other giving a false appearance. Cells are arranged in single layer, but appear multi-layered. This type of epithelium is present in the inner linings of trachea, large bronchi and helps to remove mucus. 

A simple columnar epithelium is a columnar epithelium that is uni-layered. In humans, a simple columnar epithelium lines most organs of the digestive tract including the stomach, small intestine, and large intestine. Simple columnar epithelia line the uterus.

A desmosome, also known as a macula adhaerens, is a cell structure specialized for cell-to-cell adhesion. They are transmembrane proteins that bridge the space between adjacent epithelial cells by way of homophilic binding of their extracellular domains to other desmosomal cadherins on the adjacent cell. 

Squamous epithelium (labelled c) is composed of large flat cells whose edges fit closely together like the tiles in a floor, hence it is also called pavement epithelium or tessellated epithelium. The cells rest on a thin basement membrane. If the cells are seen from the surface, they seem to be polygonal in shape. 

Correct Answer :- A

Explanation : Non-ciliated pseudostratified columnar epithelia are located in the prostate and membranous part of male vas deferens.

Bronchi are tube like structures that allow air to be transported from the surrounding atmosphere to the lung. The respiratory system (airways) consists of the trachea (essentially a large bronchi) that branch off into smaller and smaller bronchi before reaching the most distal lung alveoli, where oxygen can be transferred to the blood.

The respiratory bronchus is lined by respiratory epithelium comprising an admixture of pseudostratified ciliated columnar epithelium, goblet cells (mucin producing cells also termed mucous cells) and basal cells that function as progenitor cells for both the ciliated columnar cells and goblet cells. 

Transitional epithelium is much thinner and more stretchable than the stratified epithelium. It has a single layer of cuboidal cells at the base, two to three middle layers of a large polygonal or pear-shaped cells and a superficial layer of large, broad, rectangular or oval cells.

Histologists have recognized two more types of epithelia, which cannot be included in any of the types of covering epithelia. One is the neuroepithelial cell of epithelial origin. These cells are specialised for sensory functions, e.g. cells of taste bud. The other one is myoepithe-lial cell, which are branched cells, which con-tain muscle proteins, such as myosin and actin. 

The peritoneum consists of two layers that are continuous with each other: the parietal peritoneum and the visceral peritoneum. Both types are made up of simple squamous epithelial cells called mesothelium.

Mammary glands, which secrete milk, are apocrine type. Apical end of the cells accumulate secretory material and cell apex gets pinched off to release the product.It loses part of its cytoplasm in their secretions. Apocrine secretion is less damaging to the gland than holocrine secretion (which destroys a cell) but more damaging than merocrine secretion (exocytosis). An example of true apocrine glands is the mammary glands, responsible for secreting breast milk.