The urogenital system includes both the reproductive and excretory organs. The excretory system includes the kidneys, ureters, urinary bladder, and urethra. The kidneys function to eliminate wastes and regulate water balance and pH. They are bean-shaped organs located in the abdominal region. The urogenital system also includes the male and female reproductive organs. In males this includes the testes and male genital ducts which produce and transport sperm. In females the ovaries produce eggs which are released into the oviducts.

1. Urinogenital system
• The urogenital system includes both the reproductive
organs and the excretory organs.
• They are considered together because they share some
common ducts. We will begin by exploring the
excretory system, which is comprised of the kidneys,
ureters, urinary bladder, and urethra.
• The kidneys function to eliminate nitrogenous wastes
produced during the breakdown of proteins, regulate
water balance, pH and the ionic composition of the
body fluids. These bean-shaped organs are located in
the abdominal region adjacent to the dorsal body wall.

2. Basic structure of embryonic kidney
• Pair of compact organs lying
on either side of dorsal aorta.
• Each kidney is composed of
large no of units called as
• URINIFEROUS TUBULES OR
NEPHRONS.
• Kidney tubules arise in the
embryo in a linear series from
mesoderm.
Each uriniferous tubule is
differentiated into 3 parts.
• 1.PERITONEAL FUNNEL
• 2.MALPIGHIAN BODY
• 3.TUBULE

3. Kidneys are pair of compact
organs lying on either
Side of dorsal aorta.
Evolution of kidney takes place
as:
• ARCHINEPHROS
• PRONEPHROS
• MESONEPHROS
• METANEPHROS

4. ARCHINEPHROS
• Excretory organ of ancestral vertebrates.
• Also called as HOLONEPHROS 0r
complete kidney as it runs throughout
the entire length of coelom.
• Composed of pair of archinephric ducts.
• Each duct has a pair of tubules to a
• segment.
• Each tubule is opened by a nephrostome in
• coelom.
• Near each nephrostome there is an external
• glomerulus.
• All tubules are drained into duct
• Which opens in cloaca.

5. ARCHINEPHROS
• Larvae of caecilians and Hagfish have this type
of excretory system.
• Tissue fluid discharge from
glomerulus<<coelom<<
• Nephrostome<<tubules<<
• Archinepric ducts<<cloaca.

6. PRONEPHROS
• Embryonic tubule to appear
hence called as pronephros.
• Also called as head kidney.
• Composed of pronephric
ducts.
• Consist of 3 to 15 tubules
segmentally arranged,
• Each tubules open into
coelomby nephrostome.
• Also projecting into
coelomthere is an external
glomerulus.
• In some cases glomeruli unite
to form glomus.

7. PRONEPHROS
• All tubules of pronephros open
into the pronephric duct. Which
opens into cloaca..
• Pronephros is functional only in
embryonic or larval stage,and it is
soon replaced by mesonephros.
• Pronephros is retained
throughout life in adult
cyclostomes and teleost fishes.
• Filtrate of blood through
• glomerulus<<coelom<<nephrost
• ome<<
• Tubule<<pronephric
• duct<<cloaca.

8. MESONEPHROS
• They are also termed as
wolffian body.
• Mesonephros is
functional only in
embryos in amniotes.
• In sharks n caecilians
tubules extend
posteriorly
• Throughout coelom such
kidney is called as
OPISTHONEPHROS.

9. MESONEPHROS
• Soon with the degradation
of pronephros the
pronephric duct forms the
wolfian or mesonephric
duct.
• In amniotes mesonephros
is functional only in the
embryos and replaced by
metanephros in adults
• Nephrpstomes are
generally lacking in
embryonic amniotes.

10. METANEPHROS
• Arise posterior to the mesonephros.
• It’s the functional kidney of higher
vertebrates or amniotes.
• it is formed from the posterior end
of the nephrogenic mesoderm.
• When all metanephric tubules
develop all mesonephric ducts
disappear except those
• Associated with testis in male
forming vasa efferentia.
• It shows greater multiplication and
concentration of nephrons.
• It s functional unit is nephron.

11. METANEPHROS
• Renal Cortex:
• Renal corpuscle
• Convoluted tubules
• Renal Medulla:
• Collecting ducts
• Loop of Henle
• Each Minor calyx drains a tree
• of collecting ducts
• within a renal pyramid
• Pyramids are separated by
• columns of cortical tissues
• called renal columns
• The Renal pyramids

12. Nephron
• The tubules differentiates into the
• 1) Bowman’s capsule
• 2) Proximal convoluted tubule
• 3) Loop of Henle
• 4) Distal convoluted tubule
• The distal convuluted tubule fuses with the
collecting duct Renal corpuscle = Bowman’s
capsule/glomerulus. The nephron is the
metanephric excretory unit.
• The origin of the Renal corpuscle and tubules
is distinct from the collecting duct
(Metanephric duct)
• Duct systems merge
• Renal duct – sequence of differentiation renal
corpuscle 􀃆 proximal tubule 􀃆 distal
• tubule
• Loop of Henle elongates into the medulla

14. URINARY BLADDER

15. Urinary bladder
• Most vertebrates have urinary bladder to store
urine before it is discharged.
• FISHES: enlargement of mesonephric ducts called
• TUBAL BLADDER.
• AMPHIBIANS: termed as CLOACAL BLADDER.
• AMNIOTES: ATLONTOC BLADDER
• Mammals lack cloaca hence the kidney ducts or
ureter lead directly into the urinary bladder
which opens into URETHRA

16. GENITAL SYSTEM
• Vertebrates exhibit sexual reproduction.
• Sexes are separate with exception of few
hagfishes and few bony fishes.
• Male gonads…..Testes ….. produces sperms
• Female gonads …..Ovaries ….produces ova
• Gonads originate as a pair of genital ridges.
• Generally 1 pair of gonad are present but
some vertebrates have single gonad.

17. TESTES AND MALE GENITAL DUCTS.
• TESTES: Seminiferous
tubules: sperm factory
• Produces sperm
• Mature spermatozoa will
move to rete testis
• Then to efferent
dutules<<epididymis<<va
s deferens<<urethra.
• Testes also act as an
endocrine gland produces
teststerone.

19. OVARIES
Ovaries are found in pairs
except in some
cyclostomes and teleosts.
Ovary shows layer of
germinal epithelium
showing ova in various
stages of development.
Mature eggs are releasesd in
the oviduct .
This process is termed as
OVULATION.

22. In the absence of testosterone:
The mesonephric duct degenerates
The Mullerian duct develops uninhibited
Mullerian duct - cranial funnel-shaped opening to
The coelom forms the fimbriare of the infundibulum
The cranial Mullerian duct forms the uterine tubes
The caudal end of the Mullerian ducts fuse to form
The uterovaginal canal that later forms the uterus and the
superior vagina

23. • useful when fertilization is
internal; introduce sperm into
female reproductive tract
• found in some fish, some birds,
reptiles, & mammals
• cartilaginous fish - appendages of
pelvic fins called claspers direct
sperm into female reproductive
tract
• snakes & lizards - have pair of
HEMIPENES
• turtles, crocodilians, a few birds, &
mammals - exhibit an unpaired
erectile penis
• penis - usually a thickening of floor
of cloaca consisting of spongy
erectile tissue (corpus
spongiosum) with grooves to
direct sperm & ending in a glans
penis (sensory endings that
reflexly stimulate ejaculation)