Sodium ion reabsorption from the filtrate into peritubular blood across the cells of this component of the nephron (marked by the black asterisk)Choose from the following:(A) is regulated by the binding of the hormone aldosterone(B) is not regulated by any hormone, but is determined by sodium ion concentration and filtrate flow This image is a histological section of thyroid gland tissue, stained with hematoxylin and eosin (H&E). It shows several key features:1. **Thyroid Follicles**: These are spherical structures lined by a single layer of cuboidal epithelial cells. The follicles are filled with colloid, which is a gel-like substance primarily composed of thyroglobulin. The colloid appears homogenous and lightly stained.2. **Lumen (indicated by an asterisk)**: The central space of the thyroid follicle is where the colloid is stored.3. **Follicular Cells**: The small, dark-stained circular structures surrounding the colloid are the nuclei of the follicular cells. These cells are responsible for the synthesis and secretion of thyroid hormones.4. **Cuboidal Epithelium (indicated by an arrowhead)**: The follicular cells form a simple cuboidal epithelium, characterized by their cuboid shape and central, round nuclei.This tissue organization is critical for the production and storage of thyroid hormones, which regulate metabolism in the body. The image provides a clear representation of normal thyroid histology, useful for comparison with pathological samples.

Sodium reabsorption is a part of tubular reabsorption in kidney. This is a highly selective process. Tubular reabsorption allows material to be retrieved from tubular fluid and return these material containing nutrients, ions such as sodium, potassium, calcium etc. and other essential substances to the blood stream. Hence reabsorption is an important function performed by nephron and collecting duct.In this question, we are given an image of renal histology. the structure marked by asterisk is proximal convoluted tubule. Sodium ion reabsorption from the filtrate into peritubular blood across the cells of proximal convoluted tubule is not regulated by any hormone but is determined by sodium ion concentration and filtrate flow. In PCT, sodium ions are reabsorbed mainly due to the presence of various sodium ion channels that allow the movement of sodium ions to be diffused across the tubule. Low intracellular concentration of sodium in PCT cells favor the sodium ions to be reabsorbed by diffusion followed by water and chloride ions. Hence sodium ion reabsorption is dependent on the concentration of sodium and filtrate flow that allow sodium to diffuse passively across the tube cells resulting in reabsorption. However there are also Na+/Amino acid symporters that allow sodium ion to be transported across the tube cells along with amino acids. There are also Na+/H+ antiporters which allow sodium ion to be reabsorbed. Hence the correct answer is: (B) is not regulated by any hormone, but is determined by sodium ion concentration and filtrate flow Other option is incorrect because aldosterone stimulates sodium reabsorption mainly in distal convoluted tubule and not in proximal convoluted tubule.