Kidney

The kidneys are paired retroperitoneal organs of the urinary system. Their function is to filter blood and produce urine. Each kidney consists of a cortex, medulla and calyces. The nephron is the main functional unit of the kidney, in charge of removing metabolic waste and excess water from the blood.

Histological structures from kidney cortex :
#1. Connective tissue capsule of kidney
#2. Proximal convulated tubules of kidney cortex
#3. Distal convulated tubules of kidney cortex
#4. Renal corpuscle of kidney cortex

From kidney medulla you might identify the following histological structures:
#1. Collecting ducts and collecting tubules of kidney medulla
#2. Thin descending limb of loop of henle of kidney medulla
#3. Thick ascending limb of loop of henle of kidney
#4. Interistium and differnet capillaries at kidney medulla

the renal corpuscle of kidney cortex histology:
#1. Vascular pole of renal corpuscles
#2. Urinary pole of renal corpuscle
#3. Bowman’s capsule of corpuscle
#4. Capsular epithelium
#5. Glomerulus of corpuscle
#6. Glomerulus epithelium

reference:
https://anatomylearner.com/kidney-histology/

Ureter

The ureter is a muscular tube like structure and convey urine from the renal pelvis of each kidney to the urinary bladder. The peristaltic movement of smooth muscles layers of ureter wall helps to conduct urine from pelvis to urinary bladder.

In ureter histology you might find the following important histological characteristics under the light microscope:
#1. The epithelium (transitional epithelium) lining of tunica mucosa of ureter in animal
#2. Two or three layers of smooth muscles at tunica muscularis in different animals
#3. Fibro-elastic adventitia layer at outer part of ureter in animal
#4. Star or stellate shaped lumen of ureter of animal

reference:
https://anatomylearner.com/ureter-histology/

Urinary bladder

The urine formed by the nephrons of the kidneys is transported to the urinary bladder for storage before it gets expelled through the urethra. The urinary bladder is a sac that serves as a reservoir for urine. It is located in the extraperitoneal space of the pelvis behind the pubic bones and extends into the abdomen when filled with urine.

The microscopic structure of the urinary bladder wall organizes into the following layers from inside out.
#1. Lining epithelium
#2. Lamina propria
#3. Muscularis propria
#4. Serosa/Adventitia

reference:
https://www.ncbi.nlm.nih.gov/books/NBK540963/