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Vermiform Appendix, Anal Canal & Large Intestinal Pathologies - Coggle…
Vermiform Appendix, Anal Canal & Large Intestinal Pathologies
The Vermiform Appendix (GALT-Rich Lymphoid Organ)
Mucosa & Crytps
No villi
Rich in goblet cells
Colonic-type epithelium
With shorter, less dense Crypts of Lieberkühn
Muscularis & Serosa
Serosa
Rich in adipose tissue
Muscularis Externa
Complete Inner Circular
Outer Longitudinal Layer
Lymphoid Architecture
A nearly continuous, circumferential sheet of coalescent lymphoid follicles occupies the lamina propria and submucosa, making it a dedicated immune organ
Discontinuous Muscularis Mucosae (pierced by follicles)
Clinical Pathologies Of The Large Intestine & Appendix
Ulcerative Colitis (Rectocolitis Ulcéro-Hémorragique, RCUH)
Mucosal infiltration by :
Plasma Cells
Characteristically causes cryptitis and crypt abscesses
Polymorphonuclear Neutrophils (PMNs)
Lymphocytes
Clinical Signs :
Chronic bloody diarrhea
Abdominal Pain
Rectal Bleeding
Systemic Weight Loss
Chronic, relapsing mucosal Inflammatory Bowel Disease (IBD)
Colonic Tumors & Colorectal Cancer
Malignant adenocarcinomas
Typically evolving through the adenoma-to-carcinoma sequence
Diagnostic Tool:
Video Capsule Endoscopy (full GI visualization)
Acute Appendicitis
Leads to bacterial overgrowth and ischemic wall breakdown
Presentation: Acute right lower quadrant pain
Cause: Luminal obstruction (fecalith/lymphoid hyperplasia)
= A primary surgical emergency
= Acute inflammation of the appendix
Histology Of The Anal Canal (3 Transition Zones)
Anocutaneous Zone (Intermediate Zone - Below Pectinate Line)
Appendages
Unique zone—lacks hair follicles, sebaceous, or sweat glands
Epithelium
Stratified squamous keratinized
Sphincter
Encircled by striated perineal muscles forming the External Anal Sphincter (voluntary control)
Cutaneous Zone (Anal Margin / Perianal Skin)
Epithelium
True keratinized stratified squamous epithelium
Appendages
Fully equipped with hair follicles, apocrine/eccrine sweat glands, sebaceous glands, and rich melanin pigmentation
Anorectal Zone (Upper Zone - Above Pectinate Line)
Appendages
Fully equipped with hair follicles, apocrine/eccrine sweat glands, sebaceous glands, and rich melanin pigmentation
Epithelium
True keratinized stratified squamous epithelium