1st Lec on GIT Histology by Dr Roomi

8/2/2019 1st Lec on GIT Histology by Dr Roomi

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HISTOLOGY OF

GIT

BY

DR. MUDASSAR ALI ROOMI (MBBS, M. Phil.)



TWO MAIN COMPONENTS OF DIGESTIVE SYSTEM:

1. The digestive tract

(alimentary canal)

2. Major glands

associated with the

tract (salivary glands,

pancreas, liver

alongwith biliary

passages)



Digestive tract

Anatomically divided into

two parts:

1. The oral cavity.

2. The tubular digestive

tract which includes

esophagus, stomach,

small intestine and

large intestine.



Oral cavity

It is irregular space

bounded by the lips,

cheeks and palate.

It contains tongue,

gums and teeth.



LIPS

Core of lips: made by

skeletal muscles and

fibro-elastic C.T.

Three surfaces:

1. Cutaneous surface

2. The red area

3. Oral surface.



Histology of Lips



Histology of Lips

1. Cutaneous surface:

Covered by ordinary thin skin which contain hair follicles, sebaceous glands and sweat

glands.

Epithelium= st. sq. keratinized

2. The red area (transitional zone):

covered by modified skin. St sq non-keratinized epithelium.

Thick st. lucidum.

Numerous tall vascular dermal papillae which project into the epidermis.

Papillae are very vascular.

numerous sensory nerve endings (lips are very sensitive!).

No hair follicles, sebaceous or sweat glands

3. Oral surface:

Covered by the oral mucosa

Epith= st. sq. non- keratinized. It is thicker than that of skin area.

tall papillae in the lamina propria

labial salivary glands (mucous simple tubulo-alveolar glands)



TONGUE

It is a mass of sk. Musclescovered by the mucousmembrane.

Muscles: running in all the 3

dimensions.

Epithelium:

1. On ventral (lower) surface:

st. sq. non-keratinized

2. On dorsal (upper) surface: partially keratized,otherwise it is mainly st.sq. non- keratinized maily.



TONGUE

SURFACES OF TONGUE:

1. Dorsal surface: roughdue to presence of

lingual papillae,irregular, divided intoanterior (2/3) andposterior (1/3) by V-shaped sulcusterminalis.

2. Ventral surface



LINGUAL PAPILLAE

These are projections on the anterior 2/3 of thedorsal surface of the tongue.

Make the dorsal surface rough.

Formed by: central core of C.T. And covered by st.sq. epithelium.

Main types of lingual papillae are:

1. Filiform papillae

2. Fungiform papillae3. Circumvellate papillae

4. Foliate papillae.



LINGUAL PAPILLAE



ANTERIOR REGION OF TONGUE



LINGUAL PAPILLAE

1. Filiform papillae:

most numerous,

finger like projections,

smallest,

distributed over entire ant 2/3 of tongue,

contain no taste buds,

covered by st sq keratinized epith,

filiform= thread like

2. Fungiform papillae:

scattered singly,

fungiform= shaped like mushroom, covered by st sq non-keratinized epith,

a few taste buds on them

3. Circumvellate papillae:

8-12 in number

Located just anterior to V shaped sulcus terminalis

Numerous taste buds in the walls of trench.



LINGUAL PAPILLAE



ANTERIOR REGION OF TONGUE



GLANDS OF TONGUE

1. Anterior lingual glands:

pair,

mixed seromucous,

near the tip of tongue,

duct open on the ventral surface.2. Glands of von Ebner:

purely serous,

located in the region of circumvellate papillae,

ducts open in the trenches of circumvellate papillae,

3. Mucous glands of the root: Numerous, small, purely mucous.

Located near the posterior region of tongue.

Ducts open in the crypts of the lingual tonsils.



TASTE BUDS IN THE TRENCH OF CIRCUMVELLATE PAPILLAE



TASTE BUDS

Receptors for tastesensation.

Location: dorsal surfaceof tongue, soft palate,

epiglottis. on H/E stain, taste bud

appears as oval, palestaining body (30-50 umwide).

50-90 cells One taste pore (gustatory

pore).



TASTE BUDS

TYPES OF CELLS in the tastebuds:

1. Neuroepithelial cells:

Tall columnar cells

Basal portion of cellscontain synaptic vesicles.

2. Sustancular cells:

Function is to support

3. Basal cells:

Stem cells

1st Lec on GIT Histology by Dr Roomi

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