Module 6: Development of the Urinary and Genital Systems Flashcards
(133 cards)
1
Q
Urinary system
A
-consists of kidneys, bladder, ureters, and urethra
1
Q
Genital system
A
-includes external genitalia and internal organs including gametes and hormone producing gonads
2
Q
What does the intermediate mesoderm form
A
-kidneys and genitals
3
Q
When does the urogenital ridge first appear
A
-week 4
4
Q
What is urogenital ridge derived from
A
-intermediate mesoderm
5
Q
Divisions of the urogenital ridge
A
-genital ridge
-nephrogenic ridge
6
Q
Genital ridge
A
-will develop into genital system
7
Q
Nephrogenic ridge
A
-will form the urinary tract
8
Q
3 kidney systems
A
-pronephros
-mesonephros
-metanephros
9
Q
Pronephros
A
-first and most cranial
-develops in the cervical region
10
Q
When does development of the pronephros begin
A
-week 4
11
Q
Mesonephros
A
-formed during regression of pronephros
-develops in thoracic and lumbar regions
12
Q
When is the mesonephros functional
A
-weeks 4-12
13
Q
Mesonephros regression
A
-regresses in females but remnants go on to form several structures of male genital system
14
Q
When does mesonephros dissapear by
A
-month 4
15
Q
Metanephros
A
-permanent kidney
-replaces the primitive urinary system of the mesonephros
16
Q
When does the metanephros appear
A
-week 5
17
Q
When does metanephros become functional
A
-week 12
18
Q
Pronephros devlopment stages
A
-duct formation
-duct degeneration
19
Q
Pronephros duct formation
A
-nephrotomes begin to appear in nephrogenic ridge
-vesicles link with eachother forming a pronephric duct
-pronephric duct grows toward sacral end of embryo to reach and open into cloaca
20
Q
Pronephros duct degeneration week
A
-week 4
21
Q
Pronephros duct degeneration
A
-pronephric part of neprogenic ridge and pronephric duct regress
-remainder of pronephric duct is referred to as mesonephric duct
22
Q
Mesonephros components
A
-mesonephric tubules
-mesonephric duct
23
Q
Mesonephric tubules
A
-associated with glomeruli and drain into mesonephric duct
24
What happens during pronephros degeneration
-mesonephric tubules develop, lateral ends fuse with and open into wolffian duct
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Lateral end of mesonephric tubules
-fuses with wolffian duct and forms tubules of nephron
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When is temporary excretion pathway formed
-week 4
27
Medial end of mesonephric tubules
-small glomerular vessels grow off aorta towards these ends to form glomerulus
-these lengthen rapidly to form S shaped loop and bowmans capsule
28
How is urine excreted until week 12
-fetus swallows it and it is recycled by kidneys
-placenta is responsible for all excretion, not kidneys
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Metanephros development
-mesonephric duct develops epithelial outgrowth called ureteric bud which continues to grow into metanephric tissue
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Metanephric system components
-collecting system
-excretory system
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What interaction is essential for development of metanephric system
-interaction between ureteric bud and metanephric tissue
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Metanephric collecting system
-consists of collecting tubules within the kidneys, major and minor calyces and ureters
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Metanephric excretory system
-consists of nephrons
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Steps of development of the collecting system
-penetration
-division
-formation
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Penetration of the collecting system
-ureteric bud penetrated metanephric tissue and dilates to form primitive renal pelvis and major calyces
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Division of the collecting system
-each major calyx forms 2 new buds, which continually subdivide until 12 generations of tubules have developed
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Formation of the collecting system
-of the 12 generations of tubules
-generations 2-4 form minor calyces
-generations 5-12 elongate to form renal pyramids and collecting tubules
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Ureter duplication
-when ureteric bud splits too early
-2 ureters or 2 renal pelvises connecting to 1 ureter may result
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Ureter duplication symptoms
-often goes undetected but may present with symptoms of a urinary tract infection
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Development of excretory system steps
-nephric vesicles
-nephrons
-bowmans capsule
-tubules and loop of henle
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Nephric vesicles excretory system
-each collecting duct is covered with metanphric tissue which induces formation of nephric vesicles
-which will then develop into nephric tubules
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Excretory system nephrons
-capillaries grow into neprhic tubules and differentiate into glomeruli
-glomeruli within tubules form nephrons
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Excretory system bowmans capsule
-proximal end of each nephron forms bowmans capsule
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Excretory system tubules and loop of henle
-distal end of each nephron forms proximal convoluted tubule, loop of henle, and distal convoluted tubule
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Ascent of the kidney weeks
-weeks 6-9
46
Ascent of the kidney
-metanephric kidneys initially lie close to eachother in pelvic cavity but then move to posterior abdominal wall and further apart
47
What is ascent of the kidney caused by
-growth of lumbar and sacral regions
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Rotation of the kidney
-medial rotation which brings kidney hilus to face medially
49
Ectopic kidney
-abnormal location of one or both kidneys
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Urorectal septum
-separates urogenital tract and hindgut
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Cloaca
-shared end of urogenital tract and hindgut
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Derivatives of the urogenital sinus
-urinary bladder portion
-urethral (pelvic) portion
-phallic (flattened) portion
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Urinary bladder portion of the urogenital sinus
-largest part
-initially continuous with allantois and later becomes median umbilical ligament
54
Urethral (pelvic) portion of urogenital sinus
-gives rise to prostatic and membranous urethra in male, and female urethra
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Phallic (flattened) portion of urogenital sinus
-gives rise to clitoris and penis
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Derivatives of mesonephric duct
-ureters
-in males, ejaculatory ducts
-in females, degenerates
57
What is mesoderm of vagal trigone replaced with
-endodermal epithelium
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What is the epithelium of urethra
-endodermal
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What is smooth muscle tissue surrounding urethra derived from
-visceral mesoderm
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What forms prostate gland in males
-epithelium of prostatic urethra
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Structures of the genital system
-gonads
-genital ducts
-external genitalia
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Gonads
-responsible for producing gametes and sex hormones
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Genital ducts
-function to transport gametes through the genital system
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External genitalia
-protect internal genital tract from infection, act as sensory tissues during sexual intercourse and assist in urination
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Indifferent stage
-period preceding sexual differentiation when no differences can be observed between genetic male and female embryos
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When does the indifferent stage last until
-week 7
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Primordial germ cells
-development of testes and ovaries relies on induction from these
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Where do primordial germ cells originate
-in epiblast and migrate through primitive pit to reside in genital ridges
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Migration of primordial germ cells important weeks
-week 3
-week 6
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Week 3 of primordial germ cell migration
-migrate from epiblast through primitive pit and reside in wall of yolk sac, close to allantois
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Week 6 of primordial germ cell migration
-migrate along dorsal mesentery and invade genital
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Primitive sex cords
-form from genital ridge epithelium and precursor to cords in the testis or cortical cords
73
SRY gene
-what determines whether testes or ovaries are developed found on the chromosome and triggers development of testes
-not present in females
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Development of the testes steps
-presence of SRY
-rete testis
-AMH and testosterone
-seminferous tubules
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Development of the testes presence of SRY
-causes primitive sex cords to penetrate deep into medulla of genital ridge to form testis
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Development of testes rete testes
-toward hilum of testis
-cords dissociate to form network of tubules testis
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Development of testes AMH and testosterone
-sertoli cells develop from surface epithelium and produce anti mullerian hormone, leydig cells develop from genital ridge and produce testosterone
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Development of testes seminferous tubules
-testis cords remain solid until puberty, at puberty they canalize and acquire lumen to form seminferous
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Development of the ovaries steps
-absence of SRY
-cortical cords
-primordial follicles
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Development of ovaries absence of SRY
-primitive sex cords dissociate into irregular cell clusters which contain primoridal germ cells, these irregular cells clusters are later replaced by a vascular stroma
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Development of the ovaries cortical cords
-surface epithelium of ovary proliferates and gives rise to cortical cords which split into isolated cell clusters
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Development of the ovaries primordial follicles
-isolated cell clusters surround each oogonium with a layer of follicular cells, thereby forming primordial follicles
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Male fates of wolffian and mullerian ducts
-AMH causes mullerian ducts to regress week 8
-testosterone ensures wolffian ducts persist and differentiate
84
Female fates of wolffian and mullerian ducts
-absence of testosterone causes mullerian ducts to persist
-wolffian ducts regress by week 10
85
What are the male genital ducts formed from
-wolffian ducts
86
Male genital ducts
-efferent ductules
-paradidymis
-epididymis
-vas deferens
-ejaculatory duct
87
Efferent ductules
-rete testis joins seminferous tubules to form efferent ductules
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Paradidymis
-formed from paragenital tubules that do not join rete testis
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Epididymis
-wolffian duct elongates to form this
90
Vas deferens
-from tail of epididymis to seminal vesicle, wolffian duct obtains thick muscular coat to form this
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Ejaculatory duct
-region of wolffian duct beyond seminal vesicle
92
Gonadal dysgenesis
-karyotype 46 XY
-known as swyer syndrome
-born with external phenotypes of females and some female internal reproductive structures
-gonads are usually not functional, termed "streak gonads typically removed because of cancer
93
Development of the female genital ducts
-cranial portion
-horizontal portion
-caudal portion
94
Cranial portion
-cranial, vertical position opens into abdominal cavity which partially forms the uterine (fallopian) tube
95
Horizontal portion
-crosses the regressing wolffian ducts and forms the uterine tube
96
Caudal portion
-fuses with partner from opposite side to form uterine canal, cervix, and vagina
97
Fusion of mullerian ducts
-when horizontal portions of the mullerian duct move medio-caudally, the urogenital ridges come to lie in a transverse plane
-the ducts fuse at the midline establishing the broad ligament of the uterus
98
Divisions of pelvis
-uterus and broad ligament divide pelvis into utero-rectal and utero-vesicle pouches
99
Development of the vagina and uterus steps
-fusion
-proliferation
-canalization
100
Development of the vagina and uterus fusion
-uterus and vagina begin to form as the mullerian ducts fuse together near their attachment to the posterior wall of the urogenital
101
Development of the vagina and uterus proliferation
-2 evaginations, the sinovaginal bulbs, grow out from the pelvic part of the urogenital sinus and form the vaginal plate
-proliferation continues at cranial end of vaginal plate, increasing distance between uterus and urogenital sinus
102
Development of the vagina and uterus canalization
-by month 5, vagina is entirely canalized and vaginal fornices form
103
What is the upper portion of the vagina derived from
-uterine canal
104
What is the lower portion of the vagina derived from
-urogenital sinus
105
How is lumen of vagina separated from urogenital sinus
-by the hymen
106
Bicornate uterus
-uterine malformation resulting from impaired fusion of mullerian ducts
-partial failure of fusion of the 2 ducts resulting in a uterus divided into 2 horns
107
Development of the male external genitalia steps
-urethral groove
-penile urethra
-external urethral meatus
-scrotum
108
Development of male genitalia urethral groove
-genital tubercle forms phallus
-during elongation phallus pulls urethral folds forwards and forms urethral groove
109
Development of male genitalia penile urethra
-urethral groove extends along elongated phallus but does not reach the glans of the penis
110
Development of male genitalia external urethral meatus
-month 4
-ectodermal cells from the tip of the glans penetrate inwards and form the external urthral meatus
111
Development of male genitalia scrotum
-genital swellings grow to become scrotal swellings
-these swellings move caudally and fuse to form the scrotum
-the 2 swellings are seperated by the scrotal septum
112
Descent of the testis weeks
-weeks 6-12
113
Gubernaculum
-fibrous cord that connects the fetal testis with the bottom of the scrotum
114
Descent of the testis
-located in the abdomen and will need to descend to reside in the scrotum
115
Processus vaginalis
-evagination of the anterior vaginal wall that forms the inguinal canal
-where the testis travels to the scrotum
116
How does testis enter inguinal canal
-through deep inguinal ring
117
How does testis exit inguinal canal
-through superficial inguinal ring
118
Coverings of the testis
-external abdominal oblique muscle
-internal abdominal oblique muscle
-transversus abdominus muscle
-transversalis fascia
119
External abdominal oblique muscle
-forms the external spermatic fascia
120
Internal abdominal oblique muscle
-gives rise to cremaster muscle
121
Transversus abdominus muscle
-does not contribute to a layer of the testis
122
Transversalis fascia
-forms the internal spermatic fascia of the testis
123
Cryptorchidism
-one or both testis fail to descend into the scrotum
-may be located anywhere along the the normal path of testicular descent
124
Ectopic testicle
-rare congenital anomaly which describes a testicle that has not followed the normal route of testicular descent
125
Development of the female external genitalia
-genital tubercle elongates to form clitoris
-during elongation, clitoris if pulled forwards and forms urethral groove
-urethral groove extends along elongated tubercle and forms vestibule
-epithelial lining of urethral groove forms the urethral plate
126
Descent of the ovaries steps
-gubernaculum
-descent
-ligaments
127
Descent of the ovaries gubernaculum
-ovary descends into pelvis alongside this
-this descent is supported by the suspensory ligament which connects ovary to wall of pelvis
128
What is the suspensory ligament derived from
-mesonephros
129
Descent of the ovaries descent
-ovaries continue to descend along gubernaculum in peritoneal cavity
-also fuses with mullerian
130
How is the broad ligament formed
-2 layers of peritoneum form it
131
Broad ligament purpose
-envelops the genital organs
-fully covers the ovaries, uterus, and uterine tubes
132
Descent of the ovaries ligaments
-ovaries are fixed in place by the suspensory ligament
-gubernaculum remains as ovarian ligament and round ligament of uterus
