S2 Embryology Flashcards
What do the reproductive tracts rise from?
Reproductive tracts rise from INTERMEDIATE MESODERM.
Embryonic folding leads to a gut tube which can separated into foregut, mindgut and hindgut. Why is hindgut important?
The hindgut is important in the creation of the reproductive and urinary tracts as it gives rise to a single opening called cloaca.
What is the urogenital ridge?
An area of intermediate mesoderm which is in the posterior abdominal wall which gives rise to the embryonic kidney and the gonad.
What are primordial germ cells?
A specialised population of cells which arise from the yolk sac, and develop soon after gastrulation, they will ultimately go on to produce sperm or ova once sexual maturation has occurred,
How does differentiation of the gonad occur?
The primordial germ cells migrate along the retroperitoneum to the gonad, the karyotype of the fertilised oocyte determines the karyotype of the primordial germ cells (XX or XY) and therefore determines whether the gonad differentiates to become male or female.
What is carried on the Y chromosome?
An SRY gene, genes in this region cause differentiation of the gonad into a testis.
Other than the testes what does the SRY gene cause the development of?
The seminiferous tubules
How does internal genitalia of males form?
The presence of testes produces testosterone which drives the development of the duct system in men: epididymis, vas deferens by maintaining the Mesonephric duct.
The wolffian duct needs to be stimulated by male hormones in order to remain.
How does internal genitalia of females form?
The absence of testes causes the formation of uterus, Fallopian tubes, part of the vagina as the Mesonephric duct regresses but the PARAMESONEPHRIC duct remains.
The common elements of undifferentiated external genitalia are the genital tubercle, genital folds and genital swellings, what do these become?
Genital tubercle=
Genital folds=
Penis
Genital swellings=
Scrotum
If there is no testes present, what happens to the external genitalia?
Development of the vulva, and no fusion of the genital or swellings occur therefore labia minor and MAJORA are formed.
What is the processus vaginalis and what can happen if its not closed off?
The processus vaginalis is the area of peritoneum which pinches off to descend the testis first. It normally closes off but if not then it allows a connection to the peritoneal cavity and hence a route for hernias to occur.
What does the gubernaculum become in women?
The gubernaculum which drives the movement of ovaries (which remain in pelvis due to developing uterus) remains as the ROUND LIGAMENT and attaches to the LABIUM MAJORA, stretching this ligament during pregnancy can cause pain.
