Histopedia

  Identification Points:  1.   Serous acini   (pyramid shaped secretory cells with round basal nucleus)  2. No Serous Demilune 3.  Striated Ducts Description: It is a large capsulated serous gland, subdivided into lobes and lobules by connective tissue septa located just anterior to the ears. It secretes 25% of total saliva which is serous (watery) in nature.  At higher magnifications small secretory granules are visible in apices of serous acini Flow of Secretions: Serous acini (secretions)  ⤵️ Intercalated ducts   ⤵️ Striated Ducts (lined with Simple Columnar Cells )  ⤵️ Intra-lobular ducts  ⤵️ Interlobular duct ( Pseudo-Stratified Columnar epithelium )  ⤵️ Stensen’s Duct (open near 2nd upper molar) Step-by-step Illustration: File Diagram: How to differentiate between all 3 Salivary Glands?

 

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It is the type of epithelium in which cells appear to form several layers, but it is only one layer comprising of cells of different height and shapes and their nuclei are placed in such a fashion which gives pseudo appearance of  multiple layers. Site :  lines Upper Respiratory Passage (trachea & bronchi) Function : Filtration/Humidification of Air in URT Secretion Absorption Other Variants : Non-ciliated pseudo-stratified columnar epithelia (Prostate & Vas deferens) Pseudo-stratified columnar epithelia with   stereo-cilia (Epididymis) Important labels : Cilia Basal cells Apical cells Goblet cells Basement Membrane  

Single layer of tall and slender cells, with oval nuclei at base attached to basement membrane. Lines the most of the organs of Gastrointestinal tract. Functions: Protection (act as barrier)  Secretory (Stomach) Absorptive (Intestine) In stomach, it exhibits numerous temporary folds. Also extends downwards to form numerous indentations called Gastric Pits .

Lines the Body Cavities (Cardiac, Pleural and Peritoneal cavities), the inner surface of blood vessels (endothelium), filtration and diffusion membranes. Primary function is to allow diffusion of small molecules and gases. Important labels: Mesothelium Basement membrane Connective tissue & Smooth Muscle fibres Blood vessels Functions: Allows exchange and transport of fluid/gases Reduces friction Produces transport and lubricating fluids

Characteristic Feature:   Presence of lymphoid tissue mass in mucosa and submucosa, similar to Peyers Patches of Intestine. It’s morphology is similar to that of Colon with some modifications like muscularis externa forms a continuous coat. Less developed intestinal glands. Abundant diffused lymphatic tissue. Important labels: Lymphatic Nodules (may extend to the submucosa) Mocosa Lining Epithelium ( Simple Columnar ) with Goblet Cells Intestinal Glands (Crypts of Lieberkühn)  Lamina Propria Submucosa (rich in blood vessels) Muscularis Mucosa (myenteric plexus between inner and outer layers) Serosa (with underlying adipose tissue)   

 

Important Point: Sub-mucosa and Muscularis Mucosae are absent in Gall Bladder.  

  Serosa is only present in lower/ terminal esophagus & absent in the rest of the portion. Steps: