Category: JEJUNUM

HISTOLOGY OF JEJUNUM

HISTOLOGY OF JEJUNUM

IMAG0317IMAG0312

IDENTIFICATION POINTS

  • TONGUE SHAPED VILLI LINED BY SIMPLE COLUMNAR EPITHELIUM.
  • ABSENCE OF BRUNNER’S GLANDS IN SUBMUCOSA.
  • CRYPTS OF LIBERKUNN PRESENT

INTRODUCTION

– 2nd PART OF SMALL INTESTINE.

STRUCTURE

MUCOSA:

LINED BY SIMPLE COLUMNAR EPITHELIUM WITH FINE MICROVILLI,MUCOUS SECRETING GOBLET CELLS ARE MORE IN NUMBER. FORMED INTO LARGE FOLDS OR FINGER LIKE PROJECTIONS CALLED VILLI.’PLYCA CIRCULARIS’ IS A MUCOSAL FOLD WITH A CORE OF SUBMUCOSA.

LAMINA PROPRIA:

CONTAIN TUBULAR INTESTINAL GLANDS OR CRYPTS OF LIBERKUNN.

CRYPTS OF LIBERKUNN CONSISTS OF FOLLOWING CELLS,

1. STEM CELLS:

ACTIVE,UNDIFFERENTATED CELLS FOUND AT THE BASE OF LAMINA PROPRIA.

2. GOBLET CELLS:

SECRETE MUCOUS.

3. ENTERO ENDOCRINECELLS:

PRESENT ABOVE THE STEM CELLS.ALSO CALLED AS ‘ARGENTAFFIN CELLS’ SINCE THEY ARE STAINED BY SILVER SALTS.BELONG TO APUD (AMINE PRECURSOR UPTAKE DECARBOXYLASE) SYSTEM.

4. PANETH CELLS:

ZYMOGENIC CELLS, PRODUCING DIGESTIVE ENZYMES AND LYSOZYMES.

MUSCULARIS MUCOSA/INTERNA:

CONSISTS OF  CIRCULAR MUSCLE LAYERS.

SUBMUCOSA:

MADE UP OF LOOSE AREOLAR CONNECTIVE TISSUE.ABSENCE OF BRUNNER’S GLANDS.

MUSCULARIS EXTERNA:

CONSISTS OF OUTER LONGITUDINAL AND INNER CIRCULAR MUSCLE FIBRES. IN BETWEEN TWO LAYERS PARASYMPATHETIC GANGLION CELLS OF MYENTERIC PLEXUS CAN BE SEEN.

SEROSA:

OUTER MOST LAYER MADE UP OF FEW CONNECTIVE TISSUE CELLS AND FIBRES, COVERED BY MESOTHELIUM OF VISCERAL PERITONEUM.

FUNCTIONS:

  • VILLI HAS ABSORPTIVE FUNCTION.
  • MICROVILLI INCREASE THE SURFACE AREA OF ABSORPTION.
  • BRUNNER’S GLANDS SECRETE ALKALINE FLUID RICH IN HCO3‾.
  • MUSCULARIS EXTERNA HELPS IN CHURNING FOOD PARTICLES i.e PERISTALSIS.
  • SEROSA IS SUPPORTIVE AND PROTECTIVE IN FUNCTION.
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