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

Difference between genomes in simple eukaryote, What are the differences be...

What are the differences between genomes in simple eukaryotes vs complex eukaryotes?

What do you mean by platyhelminth phylum, Q What are the most tremendous kn...

Q What are the most tremendous known representatives of the platyhelminth phylum? The most popular representatives of the platyhelminthes are worms that cause human diseases, l

Biota of pelagic zone, Biota of Pelagic Zone Pelagic region constitute...

Biota of Pelagic Zone Pelagic region constitutes 90 per cent of the total ocean surface and is less rich in species and numbers of organisms than the two regions discussed bef

Of what subunits are ribosomes are made, Q. Of what subunits are ribosomes ...

Q. Of what subunits are ribosomes are made? Ribosomes are made of two subunits the small subunit and the large subunit. These subunits are made of proteins and ribosomic RNA (r

Discuss the biological importance of imidazole, Discuss the biological impo...

Discuss the biological importance of Imidazole. Bring in examples of biomolecules that contain this group. Please be as thorough as possible.

What is qt dispersion, Q. What is QT Dispersion? Is the difference betw...

Q. What is QT Dispersion? Is the difference between the QT interval measured from one part of the heart and the QT interval measured from another part of the heart. The QT inte

Urea molasses mineral block (ummb) licks, Urea molasses mineral block (UMMB...

Urea molasses mineral block (UMMB) licks Development of urea molasses mineral block licks is another technology being increasingly used in several parts of India and such lick

Fine structure of pollen tubes grown in vitro, Fine Structure of Pollen Tub...

Fine Structure of Pollen Tubes Grown in Vitro The growth in pollen tubes is exclusively restricted to the tip. Cytochemical analysis reveals the pollen tip zone to be rich in

What is st elevation, Q. What is ST Elevation? Although a stable LV ane...

Q. What is ST Elevation? Although a stable LV aneurysm may manifest ST-segment elevation in the precordial leads at rest. Some subjects with normal hearts show a degree of elev

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