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

Define miscellaneous functions of protein, Define Miscellaneous Functions o...

Define Miscellaneous Functions of Protein? Besides the functions enumerated above certain other important miscellaneous functions of proteins are included herewith. These inclu

Fowl spirochaetosis, Fowl spirochaetosis The causal agent Borrelia anse...

Fowl spirochaetosis The causal agent Borrelia anserina is a spiral-shaped organism about 8-30 um in length but commonly 14-15 um long and 0-3 um wide. The organisms are activel

Meningocele, Meningocele In this the meninges protrude through the op...

Meningocele In this the meninges protrude through the opening in the vertebrae generally in the lower back. The sac contains meninges and cerebrospinal fluid. The sac may

Describe coping skill and coping mechanism, Q. Describe Coping Skill and Co...

Q. Describe Coping Skill and Coping Mechanism? Coping Skill is a tool which may be used by individuals in any difficult situation like solving a problem by choosing best soluti

Power plants of the aerobic cells, Why can mitochondria be considered the p...

Why can mitochondria be considered the power plants of the aerobic cells? Ans) Mitochondria are the "power plants" of aerobic cells due to within them the final stages of the ce

Extractive use of biodiversity, Q. Extractive use of biodiversity? This...

Q. Extractive use of biodiversity? This includes direct use such as harvesting of wild plant species for use as food, fuel, fodder, fibre, shelter or medicine and hunting anima

Explain bryophytes and tracheophytes, What is the difference between bryoph...

What is the difference between bryophytes and tracheophytes? Bryophytes are nonvascular plants (mosses, hornworts, liverworts), i.e., they do not have a conductive system for t

Special characteristic of stem cells, What is the special characteristic of...

What is the special characteristic of (a) stem cells, (b) embryonic stem cells? (a) Stem cells can continue to divide throughout their life. (b)The special characteristic of

Non-rapid-eye-movement sleep, Stage 1 sleep: As an individual becomes drows...

Stage 1 sleep: As an individual becomes drowsy, and enters stage 1, alpha wave decreases and theta waves appear. Theta waves with a frequency of about 6 to 8 cycles per second are

List four possible after-effects of solvent abuse, List four possible after...

List four possible after-effects of solvent abuse (glue-sniffing). Possible after-effects of solvent abuse are headache, nausea, vomiting, convulsions, runny nose, a rash round

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