Final Answer:
The apical membranes of the tubular epithelial cells contain microvilli that increase the surface area for reabsorption. Thus, the correct option is 4. microvilli.
Step-by-step explanation:
The apical membranes of tubular epithelial cells contain microvilli, which are microscopic, finger-like projections that extend from the cell surface. These microvilli significantly increase the surface area of the cell, providing more space for the process of reabsorption to occur in the renal tubules. The increased surface area allows for more efficient absorption of water and solutes from the tubular fluid back into the bloodstream.
Microvilli play a crucial role in enhancing the absorptive capacity of cells, particularly in tissues involved in processes like reabsorption in the kidneys. The structural adaptation of microvilli on the apical membranes ensures that the cells are optimally equipped for their function in absorbing essential substances. This specialized cellular morphology is essential for maintaining the body's fluid and electrolyte balance by reclaiming valuable solutes during the filtration process in the kidneys.
Understanding the structural features of tubular epithelial cells, such as the presence of microvilli, is fundamental to grasping the physiological processes occurring in the renal system. The intricate cellular adaptations, like the microvilli on the apical membranes, showcase the precision and efficiency of the body's mechanisms for reabsorption, contributing to the overall understanding of renal function and homeostasis. hus the correct option is 4. microvilli.