Urogenital Embryology Flashcards by Iseoluwa Ojo

The genital system consists of:

a _____
___ system of gonads that ____
_____

pair of gonads

duct; carries the germ cells
external genital organs.

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The genital system develops from the following three sources:

______
Part of ____
______ covering the ______

Intermediate mesoderm

cloaca

Celomic epithelium

intermediate mesoderm

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The development of genital system begins during the ____ week of intrauterine life (IUL).
-The genetic sex (genotype XY or XX) of embryo is established at time of _____, but gonads do not acquire male or female morphological characteristics till ____ week of the development.

fertilization

seventh

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Initially (week __to__ of development) the gonads are structurally similar and hence this is called ___ stage of gonad.
-From ____ week onward, the development proceeds in different directions in males and females, and gonadal sex can then be determined morphologically.

1–6

indifferent

seventh

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By ____ week some male and female characteristics of the external genitalia can also be recognized.
-By the end of ____ week phenotypical differentiation is complete.

12th

20th

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This difference of development between male and female is because of ____ and ____ factors.

chromosomal and hormonal

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The phenotypical differentiation is determined by ___ gene located on the ____ of ____ (____)

SRY

short arm; Y chromosome ; Yp11

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The ___ chromosome is the key to sexual dimorphism because it contains the testis determining gene called the ____ gene

SRY

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SRY gene is _______

sex determining region on Y

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Under the influence of this SRY gene, ___ development occurs and during it absence the ____ development occurs.

male

female

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The SRY gene encodes for a protein called ______ (TDF)

testis determining factor

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The absence of TDF leads to development of male genital organs.

T/F

Presence

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As the indifferent gonad develops into the testis, the ___ and ___ cells differentiate to produce ____ and _______ (___).

This results in phenotypically (male or female?) embryo.

Leydig and Sertoli

testosterone; Mullerian inhibiting factor ;MIF

Male

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In the absence of the TDF, testosterone, and MIF, the indifferent gonad will develop into ___ and embryo will be phenotypically ____.

ovary

female

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Development of the Gonads

-Gonads appear as a pair of ____ called the _____

longitudinal ridges

Genital rigde.

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Genital ridge is formed by three sources of cells:

_____
______
_____

coelomic epithelium

underlying mesenchyme

primordial germ cells

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Genital ridges appear in ___ week?

3 rd!!

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the intermediate mesoderm is (medial or lateral?) to ____ part of mesonephros.

Medial

middle

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The first indication of development of primitive gonad is seen at about ___ week.

fourth

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Indifferent Gonads

An elongated elevation called _____ appears on medial side of ______
During the ____ week, the primordial germ cells migrate along _____ of ______ by ______ movement and reach the ___ at beginning of ____ week and invade it in the ____ week

genital ridge

mesonephric ridge.

fourth

dorsal mesentery of hindgut

active amoeboid

genital ridges; fifth ; sixth

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The genital ridge is formed by _____ of ______ and ____ of overlying _____

condensation

intermediate mesoderm

proliferation

celomic epithelium

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The primordial germ cells differentiate in the _____ close to ____ during ____ week.

wall of yolk sac

allantois

second

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If the primordial germ cells fail to reach the genital ridges, gonads can still develop.
T/F

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primordial germ cells have an inductive influence on the development of gonads into testis or ovary
T/F

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On arrival of germ cells into the genital ridge, the cells of surface epithelium of the genital ridge (celomic epithelium) ____ and penetrate ______ to form ____-like cords called _____ cords.

proliferate underlying mesenchyme finger primitive sex

The outer part of the indifferent gonad is called ___ and its central part is called ____

cortex medulla

Development of the Testis - the primordial germ cells carry ___ chromosome compliment under the influence of ___ gene on the ____ of Y chromosome (Yp11), which encodes for the ___, the primitive sex cords increase in ___ and extend deep into central part (medulla ) of the indifferent gonad. - These are called _____ or ______ cords.

XY; SRY; short arm; TDF length; medulla testis or medullary

Toward hilum of gonad the medullary cords ___ and ____ and ____ into tiny cell strands that _____ with each other. - The sex cords then become _____ shaped and subsequently get canalized to form _____. - The anastomosing tiny cell strands in medulla also get canalized to form ‘_____’.

regress ; break up anastomose horseshoe seminiferous tubules rete testis

In the ___ month, communication is established between the seminiferous tubules and rete testis.

fourth

The seminiferous tubules are lined by two types of cells: (a)____ cells (cells derived from _____) and (b)_____ cells (derived from ____

sex cord surface celomic epithelium primordial germ wall of the yolk sac

The primordial germ cells form _____ and the sex cord cells form ____ cells of _____

spermatogonia sustentacular; Sertoli

Sertoli cells produce ____ ( _______ ) or ____ ()

MIS mullerian inhibiting substance AMH Anti-müllerian hormone

Now the mesenchyme migrates beneath the _____, forms a tough (fibrous or serous?) layer around the ____, and seperates (cuts off) the ____ from the _____, thus blocking its contribution to the formation of sex cords (temporarily or permanently?)

celomic epithelium Fibrous developing testis sex cords celomic epithelium Permanently

celomic epithelium aka _____ epithelium

Germinal

This tough fibrous layer covering the testis is called ____

tunica albuginea

Mesoderm also forms mediastinum testis T/F

The fibrous septa arise from ___, extend toward _____, and divide the testis into _____.

mediastinum periphery various lobules

Mesoderm around the _____ forms interstitial cells of Leydig.

seminiferous tubules

By ____ week, the Leydig cells start secreting testosterone

eighth

______ is the male hormone that influences sexual differentiation of genital ducts (from mesonephric duct) and external genitalia.

testosterone

The tubules of rete testis extend into the mesonephric tissue, where they join the _____

mesonephric tubules.

The mesonephric tubules become ______ of the testis.

efferent ductules

Duct of epididymis, vas deferens, seminal vesicle, and ejaculatory duct are formed from the _______.

mesonephric duct

As the testes develop they project in the celomic cavity and are suspended from ____ abdominal wall by a mesentery called ‘ ______.’

posterior mesorchium

Development of the ovary - The primitive sex cords containing the primordial germ cells do not become ___ but ___ into the ___. - These cords dissociate into ____ called ____, which occupy the _____ part of the ovary close to the ______. - Later they _____ and are replaced by ____, which forms _____. - The surface epithelium (germinal epithelium) of female gonad, unlike that of male gonad, continues to ____ and in the ____ week forms _____ of sex cords.

prominent extend; medulla irregular cell clusters ; rete ovarii medullary;mesonephric tubules disappear; vascular stroma ovarian medulla proliferate; seventh; second generation

The ___ chromosomes bear genes for ovarian development.

Development of the ovary The second generation of sex cords containing the primordial germ cells do not extend into ______. Hence, they are also called _____ cords.

medulla cortical

In the ____ month, the cortical cords get fragmented and form isolated cell clusters. -Each cell cluster consists of a _______ in the _____ surrounded by a layer of _____

third primordial germ cell center celomic epithelial cells.

The primordial germ cells form ____ and celomic epithelial cells form _____. The resulting structure is called ‘ _____’.

oogonia follicular cells primordial follicle

All the primordial follicles remain confined in ____ of the ovary.

cortex

A small number of primordial follicles are formed during fetal life. T/F

F Large

Only few new primordial follicles are formed after birth. | T/F

F | No new

Further development of the primordial follicles takes place ______.

after puberty

In development of ovary, there’s No formation of tunica albuginea T/F

ovarian follicles are separated from surface epithelium | T/F

F They aren’t

The surface epithelium of ovary ____ to form a single layer of cells that is continuous with the ____ at ____ of the ovary. -The layer of these cells is called germinal epithelium, though it _____

flattens peritoneum at hilum does not form germ cells anymore.

The ovary is suspended from posterior abdominal wall by a mesentery called ‘______.’

mesovarium

Development of the Genital Ducts •Indifferent stage * In male the _____ ducts form the definitive genital ducts and ____ ducts mostly disappear - in female ____ ducts form the female genital ducts and the _____ ducts mostly disappear.

mesonephric paramesonephric paramesonephric mesonephric

The genital ducts of male include ____, duct of ____, ______, and _____ duct

vasa efferentia epididymis vas deferens ejaculatory

the genital ducts of female include ____,_____, and _____.

Fallopian tube uterus vagina

mesonephric ( ______ ) ducts paramesonephric ( _____ ) ducts

Wolffian Müllerian

Development of genital ducts In the male - Mullerian inhibiting Substance (= ____) : secreted by ___ cells ;causes regression of the _____ ducts - leydig cells secrete ____ that does the following: * Mesonephric tubules→ _____ * Mesonephric duct → ____,___,___,____

AMH Sertoli paramesonephric (Müllerian) testosterone ductuli efferentes; duct of epididymis, ductus deferens, ejaculatory duct, seminal vesicle

The secretion of dihydrosterone by Leydig cells stimulates the development of male external genitalia, viz., penis, scrotum, and prostate. T/F

Mesonephric duct develops in relation to mesonephros and opens into the ____ ( ____)

cloaca urogenital sinus

When the mesonephros is functional the mesonephric tubules open into the _____ -When mesonephros degenerates, most of the _____ would _____.

mesonephric duct. mesonephric tubules Disappear

Only few mesonephric tubules in the vicinity of testis persist and establish connection with ____ to form the _____ or ______ of testis.

rete testis vasa efferentia or efferent ductules

The upper part of mesonephric duct, which receives the efferent ductules, becomes ____ and _____ to form ______

elongated highly coiled duct of epididymis.

highly coiled duct of epididymis becomes wrapped in ___ to form a ____-shaped structure called _____. -Next part of the mesonephric duct develops a (thin or thick?) _____ and forms the _____

connective tissue comma epididymis thick; muscular coat ; vas deferens

The epididymis is attached to the ____ border of testis.

posterior

Just before the mesonephric duct opens into the definitive urogenital sinus (future _____), it gives a diverticulum that develops into ____

prostatic urethra seminal vesicle.

The part of mesonephric duct distal to seminal vesicle forms the _____ that opens into _____

ejaculatory duct prostatic urethra.

Development of genital duct In the females | - _____ produced by ovaries stimulates the ____ ducts to develop into the female genital ducts.

estrogen paramesonephric

The paramesonephric duct develops (medial or lateral?) to mesonephric ducts by a (vertical or horizontal?) invagination of ____ (mesothelium) and when traced caudally they cross in front of the _____ from ___ to ___ side and come close to each other in the midline.

Lateral Vertical celomic epithelium mesonephric ducts Lateral to medial

two paramesonephric ducts fuse together in midline to form a (horizontal or vertical?) duct called ______

Vertical uterovaginal canal.

Upper ends of the paramesonephric ducts remain _ into the ____ (future peritoneal cavity).

celomic cavity

The caudal end of uterovaginal canal grows ____ and comes in contact with the (ventral or dorsal ?) wall of the ___ part of the definitive urogenital sinus

down Dorsal phallic

At first, fusion between the two paramesonephric ducts is _____, being separated by a ____ - Initially 3 parts are recognized * a)A cranial part that opens into the ____ * b)a _____ part that crosses the mesonephric duct - This two parts develop into the ______ * c) a caudal part that fuses with its partner from the opposite side and forms the _____

Incomplete fenestrated septum. abdominal cavity horizontal uterine tube. uterine canal

Caudal part of the paramesonephric duct also forms the ____ and ____ in the uterus besides the uterus canal

corpus and cervix of the uterus

In fetus, which is larger, | Body or cervix of uterus

cervix is larger than the body of uterus

The initial angular junction between the two paramesonephric ducts becomes a (concave or convex?) dome and forms ___ of uterus. .

convex fundus

Myometrium of the uterus is derived from surrounding ____

mesoderm

Upper vaginal plate is derived from——- Lower vaginal plate is derived from——-

Uterovaginal canal Sinovaginal bulbs

Mesodermal upper part of vaginal plate becomes _____ part of ___ including ____ of ____

Upper vagina fornices of vagina

Endodermal lower part of vaginal plate becomes the ___ part of vagina

Lower

Thin plate of tissue separating vagina and ___ part of urogenital sinus becomes the ____

phallic hymen

estrogen also stimulates the development of female external genitalia, viz., labia majora, labia minora, clitoris, and lower portion of vagina. T/F

Development of the External Genitalia Indifferent stage (until the ___week) –fusion of cLoacal folds cranial to urogenital membrane = ______ –cloacal folds caudal to urogenital membrane : ________ and _______ ______ on each side of the urethral fold

6th genital tubercle anterior urethral folds and posterior anal fold genital swellings

So, at the indifferent stage, of development of external genitalia urogenital membrane is related to ____ medially and____ laterally

urethral fold genital swellings

Definitive stage of external genitalia IN MALE -Genital tubercle enlarges (slowly or rapidly?) and becomes _____ to form _____ -prepuce(____) is from ______

rapidly cylindrical phallus foreskin; coronary/circular sulcus

The enlargement of phallus forms the ____.

penis

genital swellings become ____ swellings that fuse in the midline to form the ____

scrotal scrotum

urogenital folds- spongious urethra T/F

IN FEMALE - The genital tubercle elongates only ___ to form _____ which bends to from ____. - The genital swellings now enlarge to form the ______.

slightly small phallus, clitoris labia majora

The clitoris contains urethra. T/F

F does not

The primitive urethral folds do not fuse and form the labia minora. T/F

The labia majora fuses with each other (anterior or posterior?) to the _____ but anterior to the ____ to form _______.

Posterior ; urogenital membrane anal membrane posterior labial commissure

The labia majora also fuses anteriorly to form _____ and _____.

mons pubis and anterior labial commissure

The labia majora overlaps the _____

labia minora.

during early stages of the development, whose genital tubercle is larger. Male or female?

Female

Descent of the Testis •Initially located in the _____ •Later move into the ____ (through the ____)

urogenital ridge scrotum inguinal canal

The testes arrive in the scrotum at about the time of ____

birth

Differential growth of the posterior abdominal wall deters the descent process T/F

F | It helps it

gubernaculum reduces in length during differential growth of the posterior abdominal wall so that testes assumes a lower position T/F

Formation of inguinal ____(inguinal canal) occurs as the testes enters into it T/F

F is formed before testes enters into it

_____ helps to dilate inguinal bursa and lays down the path for the descent of testis

Gubernaculum testis

Increased intra-abdominal pressure and Male sex hormones helps to push the testis out of abdomen T/F

A specific neurotransmitter called ________ is secreted by genitofemoral nerve supplying muscle fiber of the gubernaculum testis

calcitonin gene related peptide

Once the descent of testis is completed, the part of processus vaginalis between the ___ and the ______ is obliterated.

testis deep inguinal ring

The part of processus vaginalis that covers the testis is now known as ______ of testis.

tunica vaginalis

Descent of the Ovaries. - The ovary develops on the____ abdominal wall in the _____ region. - From here it descends into the ____ pelvis, where it lies on its (medial or lateral?) wall in a fossa called _____

posterior upper lumbar true Lateral ovarian fossa.

The caudal end of ovary is attached to the _____ by a fibromuscular band called ______ .

genital swelling gubernaculum ovarii

It is believed that the descent of ovary occurs due to __ of the ______

pull gubernaculum.

Ovary’s descent is arrested at the pelvis due to development of the _____ and _____. -This is because the gubernaculum gets attached to ____ of the developing _____.

uterus and broad ligament angle; uterus

The ____ part of gubernaculum drags the ovary into the pelvic cavity and becomes the _______.

proximal round ligament of ovary

The distal part of the gubernaculum becomes ______

round ligament of the uterus

The round ligaments of uterus pass through the inguinal canal and terminate in the _____.

labium majus

During the descent of the ovary a tubular prolongation of peritoneum, the _____ (also called _____) extends into the inguinal canal along the _____.

processus vaginalis canal of Nuck gubernaculum

The processus vaginalis (canal of Nuck) usually obliterates and disappears much before birth. T/F

Ovaries position is stabilized by two ligaments, both of which are remnants of structures associated with the ____ -Cranially, the ____ ligament of the mesonephros becomes the _____ ligament of the ovary.

mesonephros diaphragmatic; suspensory

Hypospadasis: -These defects result in failure of ______ of the ectodermal cord in the ____ and/or failure of fusion of the ____; as a consequence, there is incomplete formation of the ______. - When the external urethral orifice is on the ventral surface of the glans of the penis ( _______ hypospadias) - or on the ventral surface of the body of the penis ( ____ hypospadias)

canalization glans urethral folds spongy urethra glanular penile

Epispadias | -the urethra opens on the ____ surface of the penis.

dorsal

epispadias may occur as a separate entity | T/F

Although epispadias may occur as a separate entity, it is often associated with ____ of the ____

exstrophy of the bladder

Which is more common Epispadias or hypospadias

hypospadias

``` Micro penis: -In this condition, the penis is so ____ that it is almost hidden by the ______ -Micro-penis results from ____ failure - is commonly associated with _____ ```

small suprapubic pad of fat. fetal testicular hypopituitarism

``` Cryptorchism - ____ testis –unable to produce ____ –increased risk of ___ formation ```

undescended spermatozoa tumor

Ectopic Testes - After traversing the inguinal canal, the testis may deviate from its usual path of descent and lodge in various abnormal locations - e.g Interstitial (external to _____ of ______) - in the _____ part of the ____ thigh - _____ to the penis

aponeurosis of external oblique muscle proximal medial Dorsal

Double uterus - Latin, uterus _____ - results from failure of fusion of the ____ parts of the ____ ducts.

didelphys inferior paramesonephric

If one paramesonephric duct is retarded in its growth and does not fuse with the other one, a ____ uterus with a rudimentary ___ (——) develops.

bicornuate horn; Cornu

A unicornuate uterus develops when ____ fails to develop this results in a uterus with _____

one paramesonephric duct one uterine tube.

Testicular feminization syndrome –46, XY –the external appearance of normal ____ –tissues of the external genitalia are _____ to the ______

females Unresponsive testosterone

-The medullary cords/sex cords of testes (primordia of seminiferous tubules) remain solid until puberty. T/F

spermatogonia develop and form sperms only after puberty when the seminiferous tubules are formed by canalization of the sex cords. T/F

testicular tumor called _____ is unknown before ____ as the tumor arises from the _____, which do not develop before ____.

seminoma puberty seminiferous tubules Puberty

Appendix of epididymis: The ____ end of the ____ duct may persist as a small body called appendix of the epididymis, which is usually attached to ___ of the epididymis.

cranial mesonephric head

Paradidymis: The ____ that fail to connect with the ____ may persist and form a small body called paradidymis, which lies close to the ____ of the epididymis.

mesonephric tubules rete testis upper part

Superior aberrant ductules: These are remnants of ______ (cranial or caudal?) to efferent ductules (vasa efferentia) of the testis.

mesonephric tubules Cranial

Inferior aberrant ductules: These are remnants of ____ (cranial or caudal?) to efferent ductules (vasa efferentia) of testis.

mesonephric tubules Caudal

Appendix of testis: The ___ end of ____ duct may persist as a small vesicular body called appendix of the testis. It is found attached to the ___ pole of the testis.

cranial paramesonephric upper

Prostatic utricle: It is a (small or large?) _____ sac that opens into the _____ wall of the _____.

Small blind posterior prostatic urethra

The prostatic utricle is homologous to ____ and ______ in females.

uterus and vagina

Sinovaginal bulbs are mesodermal T/F

F Endodermal

Bicornuate uterus: In this condition, there is ___ vagina and____ cervix but the body of uterus is ___. Each half of the body is called horn or cornu of the uterus. ____ fallopian tube opens in each horn of the uterus.

one one duplicated One

Unicornuate uterus: In this condition, ____ of the uterus is missing. It occurs when ______ degener-ates so that only _____ of the uterus with ___ fallopian tube persists.

half one paramesonephric duct one horn One

Unicornuate uterus: In this condition, ____ of the uterus is missing. It occurs when one paramesonephric duct degener-ates so that only one horn of the uterus with one fallopian tube persists.

half

Urogenital Embryology Flashcards

(145 cards)