25. Physical attachment between cells important in imparting strength in tissues. Various physical cell junctions in vertebrate epithelial tissues are classified according to their primary functions. Enlisted below in column A is the major function of a particular junction and column B enlists cell junctions, but the same order.

    Choose the correct combination:
    (1) A-(i), B-(ii), C-(iii), D-(iv) (2) A-(ii), B-(iii), C-(iv), D-(i)
    (3) A-(iii), B-(iv), C-(i), D-(ii) (4) A-(iv), B-(i), C-(ii), D-(iii)

The correct match for the cell junctions and their primary functions in vertebrate epithelial tissues is:

(1) A-(i), B-(ii), C-(iii), D-(iv)

Here’s the explanation based on the major functions and typical junction types:

• A (Sealing cells to prevent leakage between them) matches with Tight junctions (i): Tight junctions create a seal that prevents paracellular transport and maintains distinct membrane domains.

• B (Linking actin cytoskeletons of adjacent cells) matches with Adherens junctions (ii): Adherens junctions connect the actin filaments of neighboring cells via cadherin proteins.

• C (Providing mechanical strength via intermediate filaments) matches with Desmosomes (iii): Desmosomes connect intermediate filaments across cells, providing strong adhesion and tissue integrity.

• D (Linking cells to the extracellular matrix) matches with Hemidesmosomes (iv): Hemidesmosomes anchor cells to the basal lamina by connecting intermediate filaments to the ECM.

Overview of Cell Junctions

Cell junctions in epithelial tissues are specialized structures that connect cells or connect cells to the extracellular matrix, enabling tissue integrity, barrier function, and communication.​

Matching Junctions to Functions

Conclusion

The combination (1) A-(i), B-(ii), C-(iii), D-(iv) is correct, reflecting the well-established roles of these junctions in vertebrate epithelia crucial for tissue cohesion, mechanical stability, and barrier functions.