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

Explain biochemical or physiological risk factors, Explain Biochemical or P...

Explain Biochemical or Physiological Risk Factors ? The biochemical or physiological risk factors are those abnormalities, some of which are metabolic in nature, which give ris

Why ammoniotelic excretion occur, Why after the passage of animals from the...

Why after the passage of animals from the aquatic to the terrestrial habitat does the abandonment of the ammoniotelic excretion occur? Ammonia is a highly toxic molecule if not

How are the male gametes of gymnosperms formed, Q. How are the male gametes...

Q. How are the male gametes of gymnosperms formed? What is the relationship between the pollen grains and the concept of alternation of generations? In the male strobiles (cone

Determine the surgical phase of implant therapy, Stage I Surgical phase ...

Stage I Surgical phase Implant placed in the maxilla or mandible After 7 days: - Sutures resorbs or are removed - Patient may be allowed to wear his/her former denture

Define methods for determining ph - nutritional biochemistry, Define Method...

Define Methods for determining pH? There are two general methods for determining pH of a solution. One is the colorimetric method and the other most common method is the use of

Explain pullulan, Pullulan Pullulan is a water soluble edible microbial...

Pullulan Pullulan is a water soluble edible microbial polysaccharide consisting of Maltotriose units (α 1 → 6), as shown in  the figure 2.12. It is produced by yeast  Aureobasi

Define the term- new life for ancient dna, Based on your reading of the art...

Based on your reading of the article "New Life for Ancient DNA" which of the following is a  false statement in regards to the comparison among genes in extinct and living species?

Biotolerant materials, Biotolerant materials, are characterized by a thin f...

Biotolerant materials, are characterized by a thin fibrous tissue interface. The fibrous tissue layer develops as a result of the chemical products from leaching processes, leading

Explain the alanine cycle, The Alanine  cycle Follow the alanine link ...

The Alanine  cycle Follow the alanine link in the alanine cycle. The process goes as under: 1)  Pyruvate formed from glycolysis in  the muscle  is converted to  alanine by t

Reagent for separation of amino acid by paper chromatography, Define Reagen...

Define Reagent for Separation of Amino Acid by Paper Chromatography? The following reagents will be required for carrying out the experiment: 1. Amino acid solution- Weig

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