Development of the Kidneys | Renal Embryology | Development of the Urinary System | Embryology

Summary

This educational video from Byte Size Med explores the stages of renal development, focusing on the anatomy and structure of the kidneys. It explains the roles of the pronephros, mesonephros, and metanephros in fetal development, detailing how they form and function. The video also covers the ascent of the kidneys from the pelvic region to the abdomen and their blood supply changes. It concludes with the formation of urine and its role in fetal life, encouraging viewers to engage with the content.

Takeaways

• 😀 The human body has two kidneys located in the abdomen, each containing millions of nephrons.
• 🔍 Each kidney is composed of an excretory portion, which includes the nephron components, and a collecting portion, which includes the collecting ducts, calyces, renal pelvis, and ureter.
• 🌱 Kidney development begins with the intermediate mesoderm, which condenses to form nephrogenic cords, leading to the formation of two kidneys bilaterally.
• 🐣 The development of the kidneys occurs in three stages: pronephros, mesonephros, and metanephros, each located at different regions of the embryo.
• 🕒 The pronephros, appearing at week four, is a primitive stage that degenerates and does not function.
• 💧 The mesonephros, which appears late in the fourth week, is functional and performs the filtration work until the metanephros takes over around 12 weeks.
• 🌟 The metanephros, forming by the fifth week, is the final kidney structure that begins to function around the 12th week of gestation.
• 🌿 The ureteric bud from the mesonephric duct induces the formation of the collecting system, including the ureter, calyces, and renal pelvis.
• 🔬 The metanephric blastema differentiates to form the excretory portion of the kidney, including the glomerulus and the renal tubules.
• ⬆️ The kidneys ascend from the pelvic region to the abdominal region as the body grows, and their blood supply transitions from branches of the abdominal aorta to the renal arteries directly.

Q & A

What are the two main functions of the kidneys?

The kidneys have an excretory function, which involves filtering waste and excess substances from the blood to form urine, and a collecting function, which involves transporting urine from the nephrons to the bladder via the ureter.

How many nephrons are present in each kidney and what is their role?

Each kidney has millions of nephrons, which are the functional units of the kidney responsible for filtering the blood, reabsorbing necessary substances, and excreting waste products in the form of urine.

What are the three stages of renal development?

The three stages of renal development are the pronephros, mesonephros, and metanephros. These stages represent the sequential development of the kidney from a primitive to a mature functional organ.

Where is the pronephros located and what is its function?

The pronephros is located in the cervical region of the embryo and is a very primitive structure consisting of cell clusters and tubules. It is non-functional and degenerates early in development.

What is the role of the mesonephros in the development of the kidneys?

The mesonephros, located between the thoracic and lumbar region, is a functional stage that performs filtration and acts as the working kidney until the metanephros takes over. It starts degenerating around the 12th week of development.

How does the metanephros contribute to the formation of the kidney?

The metanephros forms the actual kidney structure. It starts functioning around the 12th week of gestation, taking over from the mesonephros. It includes the formation of the collecting system and the excretory portion of the nephron.

What is the ureteric bud and its significance in kidney development?

The ureteric bud is a growth from the lower portion of the mesonephric duct that forms the collecting system of the kidney, including the calyces, renal pelvis, and ureter.

What is the metanephric blastema and its role in kidney development?

The metanephric blastema is a region of the nephrogenic cord that differentiates to form the excretory portion of the kidney, including the glomerulus and the renal tubules.

How does the interaction between the ureteric bud and the metanephric blastema lead to nephron formation?

The ureteric bud induces differentiation of the metanephric blastema, leading to the formation of the renal vesicle, which then develops into the S-shaped body that forms the glomerulus and the renal tubule, thus completing the formation of a nephron.

What happens to the kidneys' position as the body grows during gestation?

The kidneys initially develop in the pelvic region but ascend to the abdomen as the body grows. This ascent is accompanied by a change in blood supply from branches of the abdominal aorta to the renal arteries directly off the abdominal aorta.

How do the kidneys function during fetal life?

During fetal life, the kidneys form urine that drains into the cloaca and then into the amniotic fluid, playing a crucial role in the development and homeostasis of the fetus.