Compound or multilayered epithelia, Biology

Assignment Help:

COMPOUND EPITHELIA (MULTILAYERED EPITHELIA) -

  • These are made up of more than one layer of cells.
  • The compound epithelia may be stratified and transitinal.

1.      STRATIFIED EPITHELIUM -

  • It has many layers of epithelial cells, however, the deepest layer is made up of columnar or cuboidal cells.
  • On the basis of the shape of the cells present in the surperficial layers.

It is of four types :-

(i) Stratified Squamous Epithelium -

  • The cells in the deepest (= basal) layer are columnar or cuboidal with oval nuclei.
  • It is called germinative layer (= stratum germinativum).
  • The cells of this layer divide by mitosis to form new cells.
  • The new cells gradually shift outward.
  • In the middle layers the cells become polyhedral with rounded nuclei.
  • These are called intermediate layers.
  • The superficial layers are flat with transversely elongated nuclei.
  • These layes are called squamous layers.
  • It is of two types : (a) Keratinized Stratified Squamous Epithelium.

(b) Nonkeratinized Stratified Squamous Epithelium.

(ii) Stratified Cuboidal Epithelium -

  • It has outer layer of cuboidal cells and basal layer of columnar cells.
  • It forms the epidermis of fishes and many urodels (tailed amphibians such as salamanders). e.g. ® It also lines the sweat gland ducts and larger salivary and pancreatic ducts.

(iii) Stratified Columnar Epithelium -

  • It has columnar cells in both superficial and basal layers.
  • e.g. It covers the epiglottis and lines mammary gland ducts and parts of urethra.

(iv) Stratified Ciliated Columnar Epithelium -

  • Its outer layer consists of ciliated columnar cells and basal layer of columnar cells. e.g. ® It lines the larynx and upper part of the soft palate.

2.      TRANSITIONAL EPITHELIUM (= UROTHELIUM) -

  • This epithelium consists of 4 to 6 layers of cells.
  • The cells of deepest (= basal) layer are columnar or cuboidal.
  • The cells of middle layer are polyhedral or pear shaped.
  • The cells of the surface layer are large and globular or umbrella shaped.
  • There is no germinative layer or basement membrane but shows mitosis.
  • e.g.  renal calyces, renal pelvis, ureters, urinary bladder and part of the urethra.

Related Discussions:- Compound or multilayered epithelia

Contagious bovine pleuropneumonia, C o n t a g i o u s bovine pleu...

C o n t a g i o u s bovine pleuropneumonia It is a disease of bovines characterized by high rise of body temperature and difficulty in respiration. E t iolo

Ureotelism - excretion, Normal 0 false false false EN-I...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Define nutrition support in postoperative nutritional care, Define Nutritio...

Define Nutrition Support in Postoperative Nutritional Care? Aggressive nutritional support is important to avoid postoperative complications and mortality. Routine postoperativ

Define food processing unit operations, Define Food processing unit operati...

Define Food processing unit operations? Food processing unit operations are involved in the engineering aspects of food processing, packaging and storage. Heating, cooling, dry

Explain about the net protein ratio (npr), Explain about the Net Protein Ra...

Explain about the Net Protein Ratio (NPR)? This method was introduced by Bender and Doell (1957) and is a modification of the PER method. In this method, an allowance is made f

Vascular cambium, Vascular Cambium The vascular cambium usually, if no...

Vascular Cambium The vascular cambium usually, if not always, has a dual origin within the primary tissues; from provascular strands, and from the "ground" meristem tissues be

Explain in brief about the diseases sleep paralysis, Explain in brief about...

Explain in brief about the diseases Sleep paralysis This is an episode of paralysis in the transition between wakefulness and sleep. The period of paralysis is usually brief bu

Explain the occurrence of nictoinic acid, Explain the Occurrence of Nictoin...

Explain the Occurrence of Nictoinic acid Nictoinic acid occurs widely in the animal and vegetable kingdom in free as well as in bound form (in enzymes). Several animal organs

What is diatoms, What is Diatoms? Bacillariophyta are commonly known as ...

What is Diatoms? Bacillariophyta are commonly known as diatoms because of their unique structure. These unicellular photosynthetic organisms are composed of two overlapping glas

Management of soil productivity, Management of soil productivity The co...

Management of soil productivity The continuous prosperity and well being of the people of any nation is dependent upon several factors, one of the most important being the leve

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd