Session 1 Flashcards
Where is the Urogenital ridge?
By the posterior abdominal wall of the embryo
What tissue makes up the Urogenital ridge?
Intermediate mesoderm
What forms the gonad in the embryo?
Intermediate mesoderm of the Urogenital ridge and primordial germ cells
What do the primordial germ cells have in males only?
The Y chromosome
What drives the development of the male in embryos?
The hormone SRY
What does SRY drive the development of in male embryos?
Gonad (Testis)
Internal genitalia (Duct system)
External genitalia
What part of the indifferent gonad develops into the testis in embryos?
The medulla
What causes the development of a female embryo?
Absence of the Y chromosome
What part of the indifferent gonad develops into the ovaries in embryos?
The cortex
What is the other name for Mesonephric ducts?
Wolffian ducts
What is the other name for Paramesonephric ducts?
Mullerian ducts
What makes the Mesonephric ducts remain in the embryo?
Androgens
What happens to the Mesonephric ducts if there are no androgens present?
It regresses
What forms the Urogenital sinus?
Created from hindgut by the urorectal septum
How do the Paramesonephric ducts develop?
Appear as invaginations of the epithelium of the urogenital ridge
What makes the Paramesonephric ducts develop?
Develop either way, do not need anything to maintain them
How is the uterus and fallopian tubes formed?
The 2 Paramesonephric ducts grow towards one another and fuse to form them
How is the vagina and hymen formed?
The urogenital sinus tissue expands to make a vaginal plate which then forms the vagina and hymen
What does the testis secrete to prevent the Paramesonephric duct from developing?
Mullerian inhibiting substance (Hormone)
Why do the Mesonephric ducts regress in females?
There are no testis to release androgens to support the Mesonephric ducts
What are the 3 basic components of the indifferent stage in development of the external genitalia?
Genital tubercle
Genital folds
Genital swelling
What is the outline of the urogenital sinus?
The genital folds
In male embryos, what does the Genital tubercle and genital folds become?
The Genital tubercle elongates and fuses with the genital folds to become the spongy urethra
What does the genital swelling become?
Folding of it leads to development of the scrotum
What influences the development of the spongy urethra?
Testis derived androgen hormones, specifically Dihydrotestosterone
Why is there no fusion in the female urethra?
There is no Dihydrotestosterone present so no fusion occurs and the urethra opens into the vestible
How does the descent of the testis occur?
They are attached to the posterior abdominal wall via the Gubernaculum ligament.
As the abdomen elongates, the ligament shortens so the testis move to behind the processes vaginalis
It takes its ducts and lymphatics with it
What does the testis pass through during its descent?
Deep inguinal ring into the inguinal canal to the scrotum
How does the descent of the ovaries occur?
Gubernaculum ligament attaches the ovary inferiorly to the labro-scrotal folds. The ovary descends into the pelvis via the inguinal canal
What ligament is in the inguinal canal?
The round ligament on the uterus
