Anatomy and Histology Notes

1. Types of Cell Junctions

• Tight Junctions: Two cell membranes are “sewn” together at the apical region, forming a tight seal.

• Desmosomes: Cells interlock with each other, exhibiting a “lock and key” configuration.

• Gap Junctions: Two cell membranes are “sewn” together at the apical region, forming a tight seal.

• Adherens Junctions: These junctions feature a characteristic structure where the cytoplasm contains numerous stress fibers that traverse the membrane and interweave with each other.

2. Types of Glands

• Salivary Gland: Acinar gland

• Salivary glands + mammary glands: Compound alveolar glands (resembling a bunch of grapes)

• Lieberkuhn glands: Simple straight tubular glands

• Prostate: Tubuloalveolar glands

• Sweat gland: Simple coiled tubular glands

• Sebaceous glands: Simple alveolar glands

• Pylorus: Branched coiled tubular glands

• Interstitial glands: Diffuse glands

3. Types of Cells

• Mast Cells:

• Possess IgE receptors.

• Originate from bone marrow.

• Pericytes: Regulate the function of blood vessels.

• Endothelial Cells: Form a protective barrier – the biological barrier.

• Plasma Cells:

• Antibody-producing immune cells.

• Exhibit a well-developed endoplasmic reticulum (ER) and Golgi apparatus.

• Responsible for the synthesis and release of globulins.

• Basket Cells: Found in renal epithelium.

4. Cell Characteristics

• Leukocyte Differentiation: Differentiated based on their count on blood smears, cell size, nuclear morphology, and cytoplasmic staining patterns.

• Red Blood Cell Stability: Attributable to the Spectrin-Actin-Ankyrin complex.

• HLA Antigens: Found on the surface of leukocytes, playing a role in graft acceptance or rejection.

• Granulocytes: They are not polymorph nuclear leukocytes or polymorphonuclear leukocytes (incorrect terminology).

5. Tissue Characteristics

• Epithelial Tissue:

• Strong regenerative capacity.

• Always rests on connective tissue.

• Sparse intercellular space.

• Avascular (lacks blood vessels).

• Platelets:

• Disc-shaped and biconvex.

• Contain a cytoskeleton, collagen, mitochondria, granules, a dense tubular system, and an open canalicular system.

• Alpha granules are the most abundant type and play a critical role in hemostasis (blood clotting).

• The dense tubular system, composed of dense calcium-rich tubules, is important for leukocyte activation.

• The open canalicular system is a network of interconnected vacuoles.

6. Other Characteristics

• Gastric pits + Pyloric glands: Branched straight tubular glands

• HbA/HbF ratio: 80/20

• Site of Immunoglobulin Storage and Synthesis in Connective Tissue: Endoplasmic reticulum of plasma cell cytoplasm.

• Pro-alpha chains and alpha chains of collagen fibrils: Pro-alpha chains are synthesized in the rough endoplasmic reticulum of collagen fibril-producing cells and contain an additional non-helical peptid sequence at both ends of the molecule.

Important Notes:

• The term “tight junction” was used twice in section 1. It should be “Adherens junction” for the second instance.

• The terminology for granulocytes needs correction; “polymorph nuclear leukocytes” and “polymorphonuclear leukocytes” are incorrect.

• The “Open canalicular system” is a network of interconnected vacuoles, not channels.

• The explanation of the HbA/HbF ratio is very brief and could be expanded upon.

• The description of the pro-alpha chains and alpha chains could be clarified further.

By making these modifications, the text is more accurate and easier to understand.