Development Of Repro Tract Flashcards by Elizabeth Stevens

What is a germ cell?

Any biological cell that gives rise to gametes

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What is a karryotype?

Number and characteristics of a complete set of chromosomes within an individual

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Name the male internal genitalia

Testis
Duct system - epididymis, vas deferens, urethra
Seminal vesicles
Prostate
Bulbs-urethral glands

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Name the female internal genitalia

Ovaries

Duct system - Fallopian tube, uterus, cervix, vagina

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Name the male external genitalia

Penis

Scrotum

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Name the female external genitalia

Vagina
Vestibule
Labia majora and minora
Clitoris

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What are the male secondary sexual characteristics?

Larger body size
Body composition and fat composition
Hair and skin
Facial hair
Male pattern baldness
Central nervous system effects
Smell

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What are the female secondary sexual characteristics?

Smaller body size
Subcutaneous fat deposition
Hair and skin
Breasts
Central nervous system effects

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What is the gonad derived from and what else derived from here?

Intermediate mesoderm

Kidney

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What are the gonads known as at the very early stage?

Sex chords

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When do the sex cords acquire male/female characteristics?

Week 7

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Where do primordial germ cells arise from and where do they go?

Arise in the yolk sac

Migrate along the dorsal mesentery of the hindgut to the primitive gonads

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What is the gene that the Y chromosome carries and what does it drive development of?

SRY

Testis, duct system and external genitalia of the male

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What does the absence of the SRY a gene lead to?

Development of the female gonad (ovary), external genitalia and duct system

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What does the SRY gene code for?

Testis-determining factor

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How do the testis develop?

SRY gene codes for testis-determining factor
Primitive sex cords proliferate deep into the medulla to form the medullary cords
Towards the hilum of the gland, the cord breaks up into a network that later give rise to rete testis

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What separates the testis cords from the surface epithelium?

Dense layer of fibrous connective tissue - tunica albuginea

What do the testis cords/medullary cords become composed of?

Primitive germ cells and Sertoli cells

What lies between the medullary cords?

Leydig cells which start to produce testosterone at week 8

What happens at puberty to the testis cords?

Until puberty they are solid
Acquire a lumen forming seminiferous tubules
Join the rete testis which join the ductili efferentes which are remaining parts of the mesonephric system
They link the rete testis and mesonephric duct which becomes the vas deferens

What happens without the presence of the SRY gene?

Medullary cords in the gonad regress
Production of cortical cords
They split into isolated cell clusters which continue to proliferate
They surround each oogonium with a layer of epithelial cells - follicular cells

What are the two sets of genital ducts which initially develop in both sexes?

Mesonephric (Wolffian) ducts

Paramesonephric (Müllerian) ducts

Where do the genital ducts end?

At the cloaca

Difference between mesonephric ducts and mesonephric tubules?

Tubules form a renal function

Ducts and tubules make up the embryonic kidney

Where do the paramesonephric ducts arise from?

As an invagination of the epithelium of the urogenital ridge

Where do the paramesonephric ducts run from and to?

Caudally they contact the cloaca | Cranially they open into the abdominal cavity

What happens in the midline with the paramesonephric ducts?

They come into close contact Initially separated by a septum Fuse to form the uterine canal

What does the caudal tip of the combined paramesonephric ducts do?

Projects into posterior wall of the urogenital sinus where it causes a small swelling - the paramesonephric/Müllerian tubercle

What is on either side of the Müllerian tubercle?

Mesonephric ducts open on either side into the urogenital sinus of the tubercle

In the XY embryo, how are the different ducts supported/not supported?

Androgen secretion supports mesonephric/Wolffian ducts from Leydig cells Sertoli cells secrete Müllerian inhibiting substance so paramesonephric duct degenerates

In the XX embryo, how are the different ducts supported?

No androgen/testosterone so mesonephric/Wolffian duct degenerates No testis-derived Müllerian inhibiting hormone so the Müllerian ducts stay

At the basic stage, what is there in regards to external genitalia?

Genital tubercle Genital folds Genital swellings

What happens in males to produce the external genitalia?

Genital tubercle elongates and genital folds fuse to form the spongy urethra Happens under the influence of testis-driven androgen hormones -dihydrotestosterone

What happens in the females to produce external genitalia?

No fusion occurs so urethra opens into the vestibule

In which region do the testes arise?

Lumbar region, tethered to labioscrotal folds (future scrotum) by the gubernaculum

How does the processus vaginalis develop?

A musculo-fascial layer with the peritoneal membrane evaginates into the scrotum as it develops This forms the processus vaginalis

How do the testes descend?

Migrate over the pubic bone behind the processus vaginalis Above the testes, the fascia and peritoneum become closely apposed Fascial layers are obliterated by the stem of the processus vaginalis, testicular vessels and nerves from the spermatic cord

What is the remnant of the gubernaculum?

The scrotal ligament

Where do the ovaries begin?

Posterior abdominal wall, attached to the labioscrotal folds by the gubernaculum

What does the gubernaculum become in females?

Ovarian ligament which connects the ovaries to the uterus | Round ligament of the uterus which attaches the uterus to the labia

What do the wolffian ducts develop into?

Epididymis Vas deferens Seminal vesicles

What do the Müllerian ducts develop into?

Uterine tubes Uterus Cervix Upper vagina