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52 Cards in this Set

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  • Back
nephrogenic ridge
intermediate mesoderm which grows into a longitudinal mass running cranio-caudally
development from nephrogenic ridge
-3 systems develop from cr to ca:
1. pronephros
2. mesonephros
3. metanephros
- represents evolutionary approach to development of the kidney, example of recapitulation
- 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
-develops in thoracic and lumbar nephrogenic ridge
- mesonephric tubules functional in embryonic life
-forms: bowman's capsule and glomerulus
mesonephros in different animals
-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
bowman's capsule
1 end of the mesonephric tubule enlarges, forming this double-walled cup
tuft of capillaries derived from a series of branches of the dorsal aorta, invaginated in bowman's capsule
mesonephric duct
-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
-mammals: permanent, functional
-develops from ca part of nephrogenic ridge
-dual origin
ureteric bud (metanephric diverticulum)
-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
metanephric cap
-induced by ureteric bud
- develops into the excretory system (nephron)
further development of metanephric cap and ureteric bud
- establish connections and communications
- outer part of the metanephric mass forms the capsule and interstitial tissue of the kidney
excretory system of adult
-derived from metanephric tissue cap
1. bowman's capsule
2. proximal convoluted tubules
3. loop of Henle
4. distal convoluted tubules
glomerulus of adult
tuft of capillaries derived from a series of branches of the dorsal aorta invaginated in bowman's capsule
collecting duct system of adult
- derived from ureteric bud
1. collecting tubules
2. major and minor calyces
3. renal pelvis
4. ureter
urorectal septum
divides cloaca into:
1. dorsal rectum
2. ventral urogenital sinus
urogenital sinus
divides into parts:
1. vesicular
2. pelvic
3. phallic
- 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)
remainder of allatois
- slowly degenerates
renal agenesis
absence of one or both kidneys
horseshoe kidney
two kidneys fuse
cystic kidney
failure of union between the developing nephron and collecting tubules
ectopic ureter
ureter opens into urethra
-common in female dogs
indifferent stage of genital system
- cannot determine the morphological sex of an animal until 6-8 weeks
Genital (gonadal ridge)
-develops in ventro-medial aspect of mesonephros
-lined by coelemic epithelium which overlies a condensed mesenchyme
primordial germ cells
-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
mesonephric (wolffian) duct
-lateral to the genital ridge
-develops into male duct system
-in indifferent stage
paramesonephric (mullerian) duct
-develops dorsolateral to the mesonephric duct
-develops into female duct system
- in indifferent stage
ductspresent in indifferent stage
in each embryo
1. mesonephric duct
2. paramesonephric duct
testis determining factor (TDF)
- contained in Y chromosome
- absence results in female development
mullerian inhibitory substance
-produced by sertoli cells
-cause regression of mullerian duct
- produced by leydig cells
- stimulates the development of wolffian ducts and regression of the mullerian duct
- review freemartin
testis (gonadal) cords develop into
develops into:
1. seminiferous tubules (peripheral part)
2. rete testis: central part
primordial germ cells develop into
-differentiate into gonocytes
-after birth give rise to spermatogonia
(male) mesenchyme develops into
1. sertoli cells
2. leydig cells
tunica albugenia from
testis cords are separated from the coelomic epithelium by a this distinct mesenchymal sheet
efferent ductules from
some persisting mesonephric tubules
-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
mesonephric tubules form
- male: efferent ductules
- female: vestigeal structures
mesonephric duct forms
- male: epidydimus, ductus deferens, vesicular gland
- female: vestigeal structures
paramesonephric duct forms in males
vestigeal structures
- uterus masculinus: especially in bulls
paramesonephric ducts forms in females
1. uterine tube
2. uterus
3. vagina (partly)
vesicular part of urogenital sinus forms
- urinary bladder in both sexes
pelvic part of urogenital sinus forms
- male: pelvis urethra, prostate
- female: urethra, caudal vagina
phallic part of urogenital sinus forms in males
1. penile urethra
2. bulbourethral gland
phallic part of the urogenital sinus forms in females
1. vestibule
2. vestibular gland
urachus forms
medial ligament of the bladder in both sexes
gebernaculum forms
- male: ligament of the testes and epididymus
- female: round ligament of the uterus
genital swelling forms
-male: scrotum
- female: labia
genital tubercle forms
-male: penis
- female: clitoris
gebernaculum testis
-mesenchymal condensation extends from gonad to scrotal swelling
-descent of testes caused by: swelling of the gebernaculum testis and intra-abdominal pressure
-failure: cryptorchidism
accumulation of the fluid within the two layers of tunica vaginalis