Histology - Proximal and Distal Tubules of Nephron

Proximal convoluted tubule, aka, PCT.

Bulging cuboidal/low columnar cells
Basal membrane has infoldings with their own mitochondria.
Microvilli that make up the brush border that fills the lumen; give the lumen a characteristic "fuzzy" appearance.

The basal membrane infoldings and brush border increase the surface area for diffusion; approximately 65% of reabsorption and secretion occurs within the PCT.

Lateral processes are cytoplasmic extensions that form lateral intercellular space; held together by intercellular junctions.
Large roundish euchromatic nucleus

It has several light-staining areas of euchromatin that reflect genome activity; know that the the dark-staining areas are heterochromatin, which comprises transcriptionally inactive portions of the genome.

Abundant mitochondria, which produce visible basal striations; mitochondria support the energetic requirements of the sodium-potassium pump, which plays a key role in resorption of water and nutrients from the PCT.
Abundance of dark-staining organelles, including the vesicles and mitochondria, give PCT cells a darker hue.

Distal convoluted tubule

Cuboidal and uniform cells
Lateral processes and intercellular junctions
Basal membrane infoldings
Luminal surface does not have a brush border, so the lumen appears wider and clearer than the PCT.
Euchromatic nuclei that they tend to lie close to the lumen, even bulging into it.
Numerous mitochondria and vesicles to support their high cellular activity, though not as much as the PCT; hence, these cells appear lighter in histological samples.
Macula densa is a tightly packed region of the DCT that lies near the renal corpuscle and afferent arteriole of the nephron.