Embryology: Urogenital System

Front 1

nephrogenic ridge

Back 1

intermediate mesoderm which grows into a longitudinal mass running cranio-caudally

Front 2

development from nephrogenic ridge

Back 2

-3 systems develop from cr to ca:
1. pronephros
2. mesonephros
3. metanephros
- represents evolutionary approach to development of the kidney, example of recapitulation

Front 3

pronephros

Back 3

- 7-8 pairs of pronephric tubules form at the cr end of nephrogenic ridge
- one end of each tubule tuns ca to meet its neighbor, forming the pronephric duct
-mammals: tubules are not functional and regress, but pronephric ducts persists and continues as mesonephric duct

Front 4

mesonephros

Back 4

-develops in thoracic and lumbar nephrogenic ridge
- mesonephric tubules functional in embryonic life
-forms: bowman's capsule and glomerulus

Front 5

mesonephros in different animals

Back 5

-size correlated with type of placenta
1. endotheliochorial/ carnivores: smallest
2. sheep: intermediate
3. epitheliochorial/ pigs: largest
-larger size of mesonephros may be responsible for the normal herniation of the growing intestinal loop

Front 6

bowman's capsule

Back 6

1 end of the mesonephric tubule enlarges, forming this double-walled cup

Front 7

glomerulus

Back 7

tuft of capillaries derived from a series of branches of the dorsal aorta, invaginated in bowman's capsule

Front 8

mesonephric duct

Back 8

-other end of mesonephric tubule joins the mesonephric duct (continuation of pronephric duct)
- provides and outlet for excretory products
-persists, whereas most of the mesonephric tubules regress

Front 9

metanephros

Back 9

-mammals: permanent, functional
-develops from ca part of nephrogenic ridge
-dual origin

Front 10

ureteric bud (metanephric diverticulum)

Back 10

-arises from the caudal part of the mesonephric duct
-develops into collecting duct system
- grows into the metanephric tissues and induces them to form the metanephric cap

Front 11

metanephric cap

Back 11

-induced by ureteric bud
- develops into the excretory system (nephron)

Front 12

further development of metanephric cap and ureteric bud

Back 12

- establish connections and communications
- outer part of the metanephric mass forms the capsule and interstitial tissue of the kidney

Front 13

excretory system of adult

Back 13

-derived from metanephric tissue cap
1. bowman's capsule
2. proximal convoluted tubules
3. loop of Henle
4. distal convoluted tubules

Front 14

glomerulus of adult

Back 14

tuft of capillaries derived from a series of branches of the dorsal aorta invaginated in bowman's capsule

Front 15

collecting duct system of adult

Back 15

- derived from ureteric bud
1. collecting tubules
2. major and minor calyces
3. renal pelvis
4. ureter

Front 16

urorectal septum

Back 16

divides cloaca into:
1. dorsal rectum
2. ventral urogenital sinus

Front 17

urogenital sinus

Back 17

divides into parts:
1. vesicular
2. pelvic
3. phallic

Front 18

bladder

Back 18

- enlarged proximal part of the allantois and vesicular part of the urogenital sinus
- with development, lower part of the mesonephric (deferent) duct and metanephric (ureter) duct are separated
- metanephric duct: opens into bladder
- mesonephric duct becomes situated more caudally within the urogenital sinus (pelvic part)

Front 19

urachus

Back 19

remainder of allatois
- slowly degenerates

Front 20

renal agenesis

Back 20

absence of one or both kidneys

Front 21

horseshoe kidney

Back 21

two kidneys fuse

Front 22

cystic kidney

Back 22

failure of union between the developing nephron and collecting tubules

Front 23

ectopic ureter

Back 23

ureter opens into urethra
-common in female dogs

Front 24

indifferent stage of genital system

Back 24

- cannot determine the morphological sex of an animal until 6-8 weeks

Front 25

Genital (gonadal ridge)

Back 25

-develops in ventro-medial aspect of mesonephros
-lined by coelemic epithelium which overlies a condensed mesenchyme

Front 26

primordial germ cells

Back 26

-originate from the yolk sac
- migrates to the genital ridge which induces the development of the genital ridge to form the primitive sex cords in the mesenchyme

Front 27

mesonephric (wolffian) duct

Back 27

-lateral to the genital ridge
-develops into male duct system
-in indifferent stage

Front 28

paramesonephric (mullerian) duct

Back 28

-develops dorsolateral to the mesonephric duct
-develops into female duct system
- in indifferent stage

Front 29

ductspresent in indifferent stage

Back 29

in each embryo
1. mesonephric duct
2. paramesonephric duct

Front 30

testis determining factor (TDF)

Back 30

- contained in Y chromosome
- absence results in female development

Front 31

mullerian inhibitory substance

Back 31

-produced by sertoli cells
-cause regression of mullerian duct

Front 32

testosterone

Back 32

- produced by leydig cells
- stimulates the development of wolffian ducts and regression of the mullerian duct
- review freemartin

Front 33

testis (gonadal) cords develop into

Back 33

develops into:
1. seminiferous tubules (peripheral part)
2. rete testis: central part

Front 34

primordial germ cells develop into

Back 34

-differentiate into gonocytes
-after birth give rise to spermatogonia

Front 35

(male) mesenchyme develops into

Back 35

1. sertoli cells
2. leydig cells

Front 36

tunica albugenia from

Back 36

testis cords are separated from the coelomic epithelium by a this distinct mesenchymal sheet

Front 37

efferent ductules from

Back 37

some persisting mesonephric tubules

Front 38

follicles

Back 38

-many small clusters from broken upp gonadal cords
-contain primordial germ cells
- most situated peripherally (cortex)
- most clusters located deep in medulla degenerate
-tunica albuginea poorly developed in ovary
- mesenchymal origin

Front 39

mesonephric tubules form

Back 39

- male: efferent ductules
- female: vestigeal structures

Front 40

mesonephric duct forms

Back 40

- male: epidydimus, ductus deferens, vesicular gland
- female: vestigeal structures

Front 41

paramesonephric duct forms in males

Back 41

vestigeal structures
- uterus masculinus: especially in bulls

Front 42

paramesonephric ducts forms in females

Back 42

1. uterine tube
2. uterus
3. vagina (partly)

Front 43

vesicular part of urogenital sinus forms

Back 43

- urinary bladder in both sexes

Front 44

pelvic part of urogenital sinus forms

Back 44

- male: pelvis urethra, prostate
- female: urethra, caudal vagina

Front 45

phallic part of urogenital sinus forms in males

Back 45

1. penile urethra
2. bulbourethral gland

Front 46

phallic part of the urogenital sinus forms in females

Back 46

1. vestibule
2. vestibular gland

Front 47

urachus forms

Back 47

medial ligament of the bladder in both sexes

Front 48

gebernaculum forms

Back 48

- male: ligament of the testes and epididymus
- female: round ligament of the uterus

Front 49

genital swelling forms

Back 49

-male: scrotum
- female: labia

Front 50

genital tubercle forms

Back 50

-male: penis
- female: clitoris

Front 51

gebernaculum testis

Back 51

-mesenchymal condensation extends from gonad to scrotal swelling
-descent of testes caused by: swelling of the gebernaculum testis and intra-abdominal pressure
-failure: cryptorchidism

Front 52

hydrocoele

Back 52

accumulation of the fluid within the two layers of tunica vaginalis