BIO 342
Comparative Vertebrate Anatomy
Lecture Notes 10 - Urogenital System

Vertebrate kidneys consist of glomeruli, tubules surrounded by peritubular capillaries, & longitudinal ducts. Variations in
 kidney structure among vertebrates are primarily in the number & arrangement of the glomeruli & tubules.

1 = Bowman's capsule, 2 = glomerulus, 3 = afferent arteriole, 4 = efferent arteriole,
5 = proximal convoluted tubule, 6 = distal convoluted tubule, 7 = collecting duct,
8 = loop of Henle, 9 = peritubular capillaries


Archinephros - earliest vertebrate kidneys probably extended the entire length of the body cavity & had external glomeruli that drained the coelomic fluid

Pronephros - 1st embryonic tubules in all vertebrates; called pronephric tubules because they are the 1st to develop & are anteriorly located


Jawed fishes & amphibians - among males, some anterior tubules of mesonephros conduct sperm from testis to mesonephric duct. That part of the mesonephros is called the SEXUAL KIDNEY while the rest is the URINIFEROUS KIDNEY.

Amniote embryos - mesonephros functions for a short time after hatching or birth &, during that time, a new kidney called the
  metanephros is developing



Mammalian kidneys are divided into the CORTEX(#5), MEDULLA (#6), & PELVIS(#4):

Tubules of mammalian kidney have U-shaped Loops of Henle (avian kidney = very short loops & reptilian kidney = no loops)

Blood supply:

Urinary bladders are found in all vertebrates except agnathans, snakes, crocodilians, some lizards, & birds (except ostriches).

Value of tetrapod urinary bladder:



Translocation of testes in mammals:
Male genital ducts:


Intromittent organs:

Female genital ducts:



Vagina - fused terminal portion of oviducts that opens either into urogenital sinus or to the exterior; receives male intromittent organ

Related links:

Vertebrate Urinary Systems

Vertebrate Reproductive Systems

BIO 342 Nervous System

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