Urogenital Embryology Flashcards
The genital system consists of:
- a _____
- ___ system of gonads that ____
- _____
pair of gonads
duct; carries the germ cells
external genital organs.
The genital system develops from the following three sources:
- ______
- Part of ____
- ______ covering the ______
Intermediate mesoderm
cloaca
Celomic epithelium
intermediate mesoderm
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
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
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
This difference of development between male and female is because of ____ and ____ factors.
chromosomal and hormonal
The phenotypical differentiation is determined by ___ gene located on the ____ of ____ (____)
SRY
short arm; Y chromosome ; Yp11
The ___ chromosome is the key to sexual dimorphism because it contains the testis determining gene called the ____ gene
Y
SRY
SRY gene is _______
sex determining region on Y
Under the influence of this SRY gene, ___ development occurs and during it absence the ____ development occurs.
male
female
The SRY gene encodes for a protein called ______ (TDF)
testis determining factor
The absence of TDF leads to development of male genital organs.
T/F
F
Presence
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
In the absence of the TDF, testosterone, and MIF, the indifferent gonad will develop into ___ and embryo will be phenotypically ____.
ovary
female
Development of the Gonads
-Gonads appear as a pair of ____ called the _____
longitudinal ridges
Genital rigde.
Genital ridge is formed by three sources of cells:
- _____
- ______
- _____
coelomic epithelium
underlying mesenchyme
primordial germ cells
Genital ridges appear in ___ week?
3 rd!!
the intermediate mesoderm is (medial or lateral?) to ____ part of mesonephros.
Medial
middle
The first indication of development of primitive gonad is seen at about ___ week.
fourth
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
The genital ridge is formed by _____ of ______ and ____ of overlying _____
condensation
intermediate mesoderm
proliferation
celomic epithelium
The primordial germ cells differentiate in the _____ close to ____ during ____ week.
wall of yolk sac
allantois
second
If the primordial germ cells fail to reach the genital ridges, gonads can still develop.
T/F
F
primordial germ cells have an inductive influence on the development of gonads into testis or ovary
T/F
T
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
T
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.
X
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
T
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
T
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
T
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
T
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
T
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
T
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
T
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
T
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
T
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
T
spermatogonia develop and form sperms only after puberty when the seminiferous tubules are formed by canalization of the sex cords.
T/F
T
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
