Embryology | Development of the Urinary System

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In this lecture Professor Zach Murphy will be teaching you about the embryology and development of the urinary system. We hope you enjoy this lecture and be sure to support us below!

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[beatriznobreazevedo]

The happiness on his face is so contagious!

[kroaky]

1. Once the mesoderm develops, it is segmented into 3 parts (medial to lateral): paraxial mesoderm, intermediate mesoderm, lateral plate mesoderm (2 layers: somatic layer going with ectoderm, splanchnic layer with endoderm)

2. Folding of the trilaminar disc occurs the intermediate mesoderm starts to condense and invaginates the splanchnic mesoderm. The divot created is called the urogenital ridge. The condensed intermediate mesoderm (in the core of urogenital ridge) is called nephrogenic cord.

3. The nephrogenic cord is located behind the gut tube. At the bottom of the gut tube the cloaca is found which will later become the anal canal, bladder and urethra.

4. During week 4, around the cervical region of nephrogenic cord, the pronephros starts to develop. Which is a Duct with smaller nephrotomes (tubules). But by the end of week 4 it already starts to degenerate.

5. The mesonephros develops off the degenerating pronephros but in the thoracolumbar region. Also made of mesonephric duct and small mesonephric tubules coming out of it.

6. The mesonephros is the primitive urinary system until week 10.

7. The mesonephric tubules grow towards the aorta, and glomeruli grow from the aorta via angiogenesis. The tubules form capsules around glomeruli (bowmans capsule). Primitive urinary system. Week 5-10

8. The mesonephric duct collects the filtrate from the tubules and disposes it into the cloaca. Both hindgut and mesonephric duct empty into cloaca. The allantois empties the cloaca.

9. In the pelvic region, intermediate mesoderm condenses infront of mesonephric duct to form metanephric mesoderm. It releases growth factors to stimulate mesonephric duct to grow ureteric bud out of it. The ureteric bud also releases growth factors to stimulate metanephric mesoderm (blastema) to grow. Reciprocal induction.

10. The ureteric bud grows into the blastema and develops a ureteric stalk (ureter) connected to mesonephric duct.

11. The ureteric bud grows inside the blastema and develops the renal pelvis and major calyces from which the minor calyces develop. Millions of collecting tubules grow from the minor calyces. Collecting system.

12. Each collecting tubule has metanephric mesoderm cap around it, the collecting tubules secretes growth factors making the mesoderm condense and form metanephric vesicle and then forms the metanephric tubule which is connected to the collecting tubule.

13. The metanephric tubule then becomes the DCT and keeps growing to form the PCT and then makes a cup shape structure called bowmans capsule. The common iliac arteries form glomerular capillaries and interact with bowmans capsule. Loop of henle also formed between PCT & DCT. Bowmans capsule from PCT from DCT from collecting tubule from minor calyces…

14. The common iliac artery to the kidney degenerates and the kidney ascends and blood vessels from the top part of aorta develop and invade the kidney (renal arteries).

15. By week 10 the ureter is emptying into mesonephric duct then into cloaca. Distal part of mesonephric duct is absorbed by cloaca and then ureter is emptying directly into it. The mesonephric duct becomes a part of reproductive system.

16. The cloaca develops a urorectal septum that divides it into anterior portion (bladder) and posterior portion (anal canal). The anterior portion is called urogenital sinus which has 3 parts. Proximal part > bladder, middle part > urethra (prostatic & membranous in males), distal part > penile urethra.

[alih]

Dear Zach: You are a true Ninja. Each year you save millions of students from hard topics! You are the A team of Medicine. I am so Glad to see your channel Grow!

[ehsanulkarim]

I don't usually write comments on youtube videos but man this guy can teach! I hope that one day I can come back and donate to this channel.

Thank you from the bottom of my heart.

[ximenaguzmanrobledo]

I´m a Urology resident and I must say you've done an amazing job explaining this. Right now I'm in my pediatric rotation and this have been very useful. Thank you so much! Greetings from Colombia.

[ayeshasadiqa]

May Allah bless you zach and guide you to the TRUE path, you are helping millions of med students.Ameen

[drkasiasiuda]

Zach, I almost never give comments on youtube but this video just made my life so much easier! I have just finished watching it and now all my study notes make so much sense, the only question I am posing myself is WHY ISN'T IT TAUGHT LIKE THIS IN MY MEDSCHOOL? Keep the good job, I am getting my medcial degree thanks to you :)

[ibrahimkhalid]

I am a medical student in Pakistan. Our medical college is probably not equipped with the best of facilities in the world, but your videos really help us in tons of ways. Thank you so much, Zach! 😊

[Ohhhkkkk]

I never have imagined learning embryology would be so interesting!
You are amazingly talented and we are so blessed to have you Zach

[ranaosama]

You literally should get an Oscar for teaching medicine like that !

[kalenced]

There are no words that could describe what I feel right now. You are a true savior. My professors compared to you are nothing. Thank you so

[ombilitmnmbwalala]

I am out of words, i know that saying " Thank you so much" is not enough, I love your tutorial videos. I always watch your videos before opening my lecture notes. Keep it like that.

[MargheritaViola-lg]

I love you. I don't know how I'm just learning about your account now, but you have just SAVED me an entire afternoon trying to understand what my teachers explained. I wish you would be my teacher tbh. My med school is full of people with a giant ego and little to no capabilities of teaching <3

[praiseyoma]

The joy after understanding this is just indescribable. I love you... all the way from Ghana

[xtellii]

I just want to say I have watched so many of your videos and you've saved my ass so many times from confusing lectures from undergrad all the way into med school now. You're amazing!!! thank you and please don't stop making videos.

[wasnt.here.]

My med school is asking for donations from alumni. They're not getting anything because it's all going to his patreon once I graduate.

[scamacca]

i'm a 19 years old Italian medical student and i have no words to describe what this video means to me. Absolutely brilliant content. Subbed.

[Max-pihc]

Watching this from Germany! I got so frustrated with this topic! You made it so easy to grip and understand. Love it! Thank you for your work and dedication to all the videos!

[himanshuambilkar]

Goosebumps while watching, I was not able to understand this topic for so long . Thank you Zach sir

[medicoUsamaNaseer]

Almost seen half video...

ماشاءاللّٰه

You teach well!