Histology of Vermiform Appendix

Mucosa-associated lymphoid tissue (MALT) is scattered along with mucosal linings, measuring roughly 400 m2. It is the most extensive component of human lymphoid tissue. These surfaces protect the body from an enormous quantity and variety of antigens. The tonsils, Peyer patches within the small intestine, and the vermiform appendix are examples of mucosa-associated lymphoid tissue (MALT).

IDENTIFICATION POINTS

VILLI ARE ABSENT.
LAMINA PROPRIA CONTAINING LYMPHOID AGGREGATIONS.
THICK MUSCULARIS EXTERNA.
INTRODUCTION

– VERMIFORM APPENDIX IS A WORM LIKE DIVERTICULUM ARISING FROM POSTERO-MEDIAL WALL OF CAECUM.

– LENGTH OF 20cm, AVERAGE LENGTH IS 9cm.

STRUCTURE

MUCOSA:

LINED BY SIMPLE COLUMNAR EPITHELIUM WITH FINE MICROVILLI, MUCOUS SECRETING GOBLET CELLS ARE MORE IN NUMBER. VILLI ARE ABSENT.

LAMINA PROPRIA:

CONTAIN FEW TUBULAR INTESTINAL GLANDS OR CRYPTS OF LIBERKUNN AND NUMEROUS AGGREGATIONS OF LYMPHATIC NODULES WHICH EXTEND INTO SUB MUCOSA.

MUSCULARIS MUCOSA/INTERNA:

THIS LAYER CONSISTS OF DISRUPTED CIRCULAR MUSCLE LAYERS.

SUBMUCOSA:

MADE UP OF LOOSE AREOLAR CONNECTIVE TISSUE WITH MORE BLODD VESSELS. CONTAINS SOME LYMPHOID TISSUE WHICH IS MIGRATED FROM LAMINA PROPRIA.

MUSCULARIS EXTERNA:

CONSISTS OF OUTER LONGITUDINAL AND INNER CIRCULAR MUSCLE FIBRES WITH MYENTERIC NERVE PLEXUS IN BETWEEN.

SEROSA:

OUTERMOST LAYER WITH FEW ADIPOCYTES.

**VERMIFORM APPENDIX IS RUDIMENTARY IN NATURE, HENCE IT DOES NOT PERFORM ANY FUNCTION.

CLINICAL:

INFLAMMATION OF VERMIFORM APPENDIX IS CALLED AS ‘APPENDICITIS‘. IT IS CAUSED EITHER BY OBSTRUCTION OR INFECTIONS.
SURGICAL REMOVAL OF VERMIFORM APPENDIX IS TERMED AS ‘APPENDICECTOMY‘