Category: LARGE INTESTINE(COLON)

HISTOLOGY OF LARGE INTESTINE(COLON)

HISTOLOGY OF LARGE INTESTINE(COLON)

IMAG0323L INTST

IDENTIFICATION POINTS

  • FOLDS OF MUCOSA WITHOUT VILLI.
  • NUMEROUS GOBLET CELLS.
  • ADIPOCYTES IN SUBMUCOSA
  • MUSCULARIS EXTERNA WITH OUTER LONGITUDINAL AND INNER CIRCULAR MUSCLE FIBRES.

INTRODUCTION

– 6 FEET IN LENGTH

– DIVIDED INTO CAECUM,ASCENDING COLON, DESCENDING COLON,TRANSVERSE COLON AND SIGMOID COLON.

STRUCTURE

MUCOSA:

LINED BY SIMPLE COLUMNAR EPITHELIUM RICH IN GOBLET CELLS. VILLI ARE ABSENT.

LAMINA PROPRIA:

CONTAIN TUBULAR INTESTINAL GLANDS OR CRYPTS OF LIBERKUNN. BUT HERE CRYPTS OF LIBERKUNN ARE DEVOID OF PANETH CELLS.

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.

MUSCULARIS MUCOSA/INTERNA:

THIS LAYER CONSISTS OF CIRCULAR MUSCLE LAYERS.

SUBMUCOSA:

MADE UP OF LOOSE AREOLAR CONNECTIVE TISSUE. PRESENCE OF NUMEROUS ADIPOCYTES.

MUSCULARIS EXTERNA:

CONSISTS OF OUTER LONGITUDINAL AND INNER CIRCULAR MUSCLE FIBRES. IN CERTAIN REGIONS OF COLON LONGITUDINAL MUSCLE LAYERS BECOME VERY THICK RESULTING IN FORMATION OF THREE BAND LIKE STRUCTURES CALLED’TAENIA COLI’.

SEROSA:

IT IS SAID TO BE INCOMPLETE IN POSTERIOR ASPECT OF ASCENDING AND DESCENDING COLON. HERE IT SHOWS MANY PERITONEAL POCKETS FILLED WITH ADIPOSE TISSUE AND IS TERMED AS ‘APPENDICES EPIPLOICAE’.