QuestionSBA
QuestionChoice
This is not the correct answer. In the fourth week, the pronephros appear in the cervical region of the embryo. It is non-functional and regresses completely by the end of that week, leading to the development of the mesonephros which functions as the primitive excretory system. As such, while it is true that the kidneys become functional by the twelfth week of gestation, it is not accurate that the definitive kidney, the metanephros, is formed by week 4 as the metanephric system is formed in the fifth week of gestation.
10027357
b
4, 12
QuestionChoice
This is the correct answer. In the fourth week of gestation, the pronephros appear in the cervical region of the embryo. It is non-functional and regresses completely by the end of that week, leading to the development of the mesonephros which functions as the primitive excretory system. Ureteric buds develop from the mesonephric ducts, which are a remnant of the pronephric duct, and this induces the development of the definitive kidney known as the metanephros by week 5 of development. The metanephric system is composed of the excretory and collecting system and its development is initiated in the pelvis during the fifth week before the kidneys ascend into the abdomen and become functional by the twelfth week of gestation.
10027356
a
5, 12
QuestionChoice
This is not the correct answer. While it is correct that the definitive kidney (i.e. the metanephros) is formed in week 5, it is not true that the kidneys become functional by week 7. By the seventh week of gestation, the cloaca is divided into two structures by the urorectal septum, namely the urogenital sinus and the anal canal. The kidneys become functional when they ascend into the abdomen by the twelfth week of gestation.
10027359
d
5, 7
QuestionChoice
This is not the correct answer. While it is correct that the kidneys become functional by the twelfth week of gestation, it is not true that the definitive kidney, the metanephros, is formed by week 7 as the metanephric system is formed in the fifth week of gestation.
10027360
e
7, 12
QuestionChoice
This is not the correct answer. The metanephric system is formed in the fifth week of gestation, as such, the definitive kidney (i.e. the metanephros) is formed in week 5, not 4. The significance of the seventh week of gestation is that during weeks 4-7 of gestation, the cloaca is divided into two structures by the anorectal septum, namely the urogenital sinus and the anal canal. It does not indicate the stage of gestation when the kidney becomes functional as the development of the metanephros is initiated in the pelvis during the fifth week before the kidneys ascend into the abdomen and become functional by the twelfth week of gestation.
10027358
c
4, 7
Concept
Chapter
2693
4466
Development of the urinary tract
Topic
171
Embryology
17869
Which option is most appropriate to complete this statement - The definitive kidney is formed by week __ and becomes functional by week __
a