2nd Lecture on the Histology of Urinary System by Dr. Roomi

7/31/2019 2nd Lecture on the Histology of Urinary System by Dr. Roomi

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Histology

of Urinary System

By

Dr. Mudassar Ali Roomi (MBBS, M.Phil)


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Parts of nephron

Bowmans capsule

Renal corpuscle= Bowmans

capsule+ glomerulus Proximal tubule = PCT+ PST

Intermediate tubule = thin

segment

Distal tubule = DST + DCT

Loop of Henle= PST + DST+

Thin segment

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Proximal

convoluted tubule

(PCT)

PCT is similar histologically to PST.

Simple Cuboidal or low columnar epithelium

Longer (14mm) than the distal convoluted

tubule. So,more frequently seen in sections

of renal cortex.

diameter= 50-60 um

Eosinophilic cytoplasm.numerousmitochondria

Cell apex has abundant long microvilli which

form a prominent brush borderfor

reabsorption.

Apical part of cell also show a lot of vesicles.

Prominent lateral interdigitation of cells.

Basal striations of the cells: Numerous

mitochondria compartmentalized in the

basal region by extensive infoldings of the

basal plasma membrane.

Because the cells are large, each transverse

section of a proximal tubule typically

contains only 3-5 rounded nuclei. Function: ?

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Loop of Henle

U-shaped structure.

Several parts

thick, descending portion

(PST)

thin segment (dia= 15 um)

Thick ascending segment

(DST)

Thin segment is lined by

simple squamous epithelialcells having a few microvilli.

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Distal convoluted tubules (DCT)

It is much shorter in length(5mm)

has a wider lumen than PCTbecause the cells are low inheight.

DCT is similar histologically toDST.

Simple cuboidal cells (6-8 cellsper cut section)

cytoplasm= faintly acidophilic

Have no brush border and are

smaller than the cells of proximaltubules.

Function:?

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PCT Vs DCT

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COMPARISON

PCT

1. Longer, so more cut sections

2. More outer diameter

3. Less diameter of lumen4. 3-5 cells per section

5. Low columnar cells

6. More eosinophilic cytoplasm

7. Brush border present8. Prominent lateral

interdigitations of cells-

present

DCT

1. Shorter, so less cut sections.

2. Less outer diameter

3. Wider lumen4. 6-8 cells per section

5. Low cuboidal cells

6. Less eosinophilic cytoplasm

7. No brush border8. Lateral interdigitations of

cells not prominent


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Collecting Tubules & Ducts

The collecting tubules are lined

with cuboidal epithelium.

Cells of the papillary collecting

ducts of Bellini are columnar

Centrally placed dark stainingnucleus

Cytoplasm stains faintly

No brush border

No basal striations

Function=?

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Juxtaglomerular

apparatus (JGA)

Specialized structure

Made by The initial, straight part of the distal

tubulemaking contact with The vascular

pole of the renal corpuscle of its parent

nephron.

Macula densa

Thickened part of the distal tubules that is in

contact with the arterioles of renal corpuscle.

columnar and more closely packed.

Apical nuclei, basal Golgi complexes.**

Acts as a Sensor of osolarity: A more

elaborate and varied system of ion channels

and transporters.

Juxtaglomerular Granular (JG) cells

Present adjacent to the macula densa, in thetunica media of the afferent arteriole.

Modified smooth muscles (epitheloid cells)

cells with secretory nature (renin)

More rounded nuclei, rough ER, Golgi

complexes and zymogen granules

Lacis cells

extraglomerular mesangial cells Function?

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comparison


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comparison


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HOW TO DRAW KIDNEY!


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Ureter- how to draw it!

2nd Lecture on the Histology of Urinary System by Dr. Roomi

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