Lecture 2: Development of the reproductive tract Flashcards
The urinary and genital system is closely associatedly, particularly in males. Which part of the urogenital system is shared (urine and sperm both)?
Urethra
The urogenital tract originates from which embryological structure?
Intermediate mesoderm
In kidney development, there are three slightly overlapping kidney structures that are formed during development.
Name the three structures?
Pronephros
Mesonephros
Metanephros
(s before t)
**NOTE remember this development occurs on the other side of the embryo too (as there are two kidneys that develop)**
Describe the formation of the pronephros?
- At the beginning of the 4th week of development, the pronephros is represented by 7-10 solid cell groups, thickened mesoderm.
- These solid cell groups are located in the cervical region
- By the end of the 4th week the pronephric system has regressed.
What is the functional capacity of the pronephros?
Rudimentary and nonfunctional
Regresses before more caudale kidney systems form
Where is the location of the pronephros?
Cervical region
Describe the formation of the mesonephros?
- Derived from intermediate mesoderm from the upper thoracic to upper lumbar segments.
- During the regression of the pronephric system (end of week 4), the first excretory tubules of the mesonephros appear.
- Solid rod of mesoderm begins to form
The sequence of the formation of the kidney systems goes from which end to which end of the embryo?
Cranial to caudal
What is the functional capacity of the mesonephros?
Has the capacitiy to be functional for a short time during the early fetal period however regresses
The metonephros is known as the what?
Definitive kidney
What week does the metanephros appear?
Week 5 of development
How long does it take for the metanephros to become fully functioning kidneys
Takes 6 weeks
Overall, about week 11 of development
The metanephros is formed from which two structures?
- Ureteric bud
- Metanephric cap
The ureteric bud is an outgrowth of the?
Mesonephric duct
Name these kidney structures?
Name these parts of these embryological structures?
Define the cloaca?
Common chamber for the hindgut and urinary systems
Important in waste removal, including the kidneys
The ureteric bud is going to develop into which structure(s) of the permanent kidney?
The collecting system
Allows urine drainage from the developing kidneys
The metanephric cap is going to develop into which structure(s) of the permanent kidney?
Excretory units
Urine production begins for form when?
In early gestration
Remember the kidneys are fully formed by week 11/12
The anterior portion of the cloaca forms?
The urogenital sinus i.e. the bladder
The posterior portion of the cloaca forms?
The anus
What happens to the cloaca during the 4 to 7th week of development?
The cloaca divides into the urogenital sinus (anteriorly) and the anal canal (posteriorly).
What is the function of the urorectal spetum?
This is a layer of mesoderm between the anterior and posterior parts of the cloacal.
It divides cloaca (into anterior and posterior) by fusion with cloacal membrane
Name these parts that are a involved in the division of the cloaca?
What does the bladder form from?
The urogenital sinus and caudal parts of the mesonephric duct
What is the function of the allantois?
Not really functionally important in humans
Describe the process of the division of the cloaca?
The urorectal septum begins to form in the hindgut.
The septum grows forwards towards the cloacal membrane.
The urorectal septum and cloacal membrane will fuse creating two distinct openings of the cloaca.
Anterior: the opening to the bladder.
Posterior: the opening to the rectum
The bladder is formed from which embryological structure?
The cranial part of the urogenital sinus
When do the gonads acquire male or female morphological characteristics?
Week 7
Until this point males and females are indistinguishable