1. Comparative Anatomy Urogenital System
Kardong
Chapter 14
Part 14

2. Urogenital System
Ducts of excretory and reproductive systems are intimately associated with each other
Figure Embryonic
origin of the kidneys (book figure 14.4).
Figure Evolutionary development of kidneys in vertebrates.

3. Primitive Kidney Archinephros- primitive excretory kidney organ
Holonephric concept - (3 kidneys are a part of one organ)
Filtration system
Archinephric duct- drains to cloaca or bladder
Figure Hypothetical archinephros.

4. Primitive Kidney (cont.)
Pronephros
1st tubules to appear
Anteriorly located; head kidney
Involutes to form lymphoidal mass
Only functions temporarily
All tubules associated with pronephros
Pronephric (archinephric) duct drains pronephros
Figure Three-part kidney (book figure 14.5).
Figure Pronephros – anterior region of primitive kidney.

5. Kidney Structure (cont.)
Figure Pronephric, mesonephric, and metanephric system relationships (see book figure 14.6).
Figure Fate of nephrogenic mesoderm (red).

6. Kidney Structure (cont.)
Mesonephros (opisthonephros)- kidney mass caudal to pronephric region
Functional adult kidney of fish and amphibians
Opisthonephros - in most adult amphibians and fishes.
Drained by mesonephric (archinephric) duct
Figure Mesonephros of urodeles (see book figure 14.8)
Figure Mesonephric duct of opossum embryo.

7. Urogenital Anatomy Ductus efferens: Pronephric duct Mesonephric duct
Archinephric duct (= wolffian duct)
Anterior portion of mesonephric tubules used in male reproductive system
Figure Urogenital system and adrenal glands of male frog.

8. Urogenital Anatomy (cont.)
Figure Mesonephric kidneys with mesonephric duct (black) carrying sperm and/or urine (see book figure 14.24).

9. Urogenital Anatomy (cont.)
Accessory urinary ducts
Tubules also in reproductive sys.
Path for sperm to enter mesonephric duct (sperm duct)
Figure Mesonephric kidneys with separate sperm duct (red) (see book figure 14.24).

10. Urogenital Anatomy (cont.)
Pronephros
Lost
Mesonephros
Mainly an embryonic kidney
Involutes at birth
Metanephric kidney
Takes over functions of mesonephros
Ureter- new duct drains meta. kidney
Figure Metanephric kidney assuming superior position to remainder of urogenital system.

11. Urogenital Anatomy (cont.)
Mesonephric duct
Sperm duct in males
Ductus deferens in amphibians
Vas deferens in mammals
Terminate at cloaca
Most amniotes
Not in higher vertebrates
Figure Male teleost, caudal end of urogenital system.

12. Summary of Embryonic Amniote Urogenital Anatomy
Pronephros involutes
Mesonephros involutes
Metanephric kidney develops
Vas deferens (sperm duct in mammals)
Table 1. Terminology of
the urogenital system (book
Figure 14.21).

13. Urinary Bladder Found in most vertebrates Formation varies
Fish- terminal segment of mesonephric duct
Large bladders- turtles and lizards
Turtles- accessory bladder
Figure Evolution of the urinary bladder (book figure 14.53).

14. Gonads Elevated ridges medial to kidneys
Gonads enlarge, suspended by mesenteries
Mesorchium- males
Mesovarium- females
Figure Urogenital ridge in developing embryo (book figure 14.18).
Figure Ovary of hagfish (book figure 14.23).

15. Gonads (cont.) Bidder’s organ Rudimentary ovary of toads (genus
Anaxyrus—formerly Bufo)
If testes removed, become functional ovary
Ovotestes in fish
Both ovary and testis in lizards
Multi-lobed testis in some species of salamanders (genus Desmognathus)
Figure Left bidder’s organ of male Anaxyrus.

16. Male Urogenital System (cont.)
Figure Urogenital anatomy of male fishes (book figure 14.33).

17. Male Urogenital System (cont.)
Figure Urogenital anatomy of tetrapod males (book figure 14.35).

18. Female Gonads (cont.)
Figure Urogenital anatomy of female fishes (book figure 14.25).

19. Female Gonads (cont.)
Figure Urogenital anatomy of tetrapod females (book figure 14.27).

20. Copulatory Organs Claspers in cartilagenous fish Gonopodium in teleost
Intromittent organ
Hemipenes
Single penis
Figure Gonopodium of a male guppy.

21. Copulatory Organs (cont’d.)
Figure Intromittent organs
in the chondrichthyans
(book figure 14.38).

22. Copulatory Organs (cont.)
Figure Intromittent
organs in the turtles and crocodylians (book figure 14.42).

23. Copulatory Organs (cont.)
Figure Intromittent organs in birds—domestic turkey (book figure 14.44).

24. Copulatory Organs (cont.)
No copulatory organs
Sperm pocket- Spermatheca in most salamanders
Rudimentary copulatory organ
Some amniotes (tuatara)
Cloacal apposition
Male and female cloacae come together
Figure Penis in the dog (book figure 14.45).

25. Cloaca
Receives digestive, reproductive, and urinary products and tracts
No cloaca
Fish – may have three separate openings
Lost in mammals above monotremes
Cloaca subdivisions:
Coprodaeum
Urodaeum
Proctodaeum
Figure Cloacal cavities and urogenital structures in a salamander.

26. Cloacal Subdivisions Coprodeum Receives alimentary canal
Simple columnar
Urodeum
Receives urinary and reproductive products
Transitional epithelium
Proctodeum
Associated with excretory
Stratified squamous
Figure Subdivisions of cloaca shown in a lizard.

27. Urogenital Papilla Sperm
Cloacal gland
Ductus deferens
Ureter
Cloacal cavity
Sperm
Typically found in chondrichthyans and squamates.
Figure Urogenital papilla
in snakes.

28. Cloacal Region of a Bird
Figure Bird cloacae (book figure 14.49).

29. Bird Cloaca (cont.) Bursa of Fabricius Lymphoid evagination off cloaca
Figure Bursa of Fabricius on young bird.
Figure Histology of Bursa of Fabricius and cloaca.

30. Urogenital System (cont.)
Figure Urogenital systems of female tetrapods (book figure 14.28).

31. Urogenital System (cont.)
Muellarian ducts
In males, ducts are nonfunctional
In females, ducts give rise to female reproductive tract
Only left reproductive tract
Birds and crocodiles
Raptors have vestigial right reproductive tract
Figure Book figures and

32. Reproductive Tracts of Mammals
Duplex uterus
Monotremes and marsupials
Separated female reproductive tracts
Bipartite uterus
Rabbit
Body of uterus seems unpaired, yet has two lumens
Bicornuate uterus
Cat
Two uterine horns and single lumen
Figure Morphology
of uteri (book figures ).

33. Reproductive Tracts of Mammals (cont.)
Bicornuate uterus
Cat
Two uterine horns and single lumen
Simplex uterus
Primates
Large body and horns
Figures Mammalian uteri; fused muellerian ducts (blackened regions) and cloaca (red).

34. Reproduction Most vertebrates require both sexes
Some vertebrates are asexual
Reproduce parthenogenetically
Some fish and lizards
Embryonic humans are asexual
Until differentiation of sexual structures

35. Differentiation of Sexual Structures
Figures Mesonephros contributions to male and female reproductive tracts.

36. Differentiation of Sexual Structures in Mammals (cont.)
Genital tubercle
Male - penis
Female - clitoris
Genital folds
Male - penis contribution
Female - labia minora
Genital swellings
Male - scrotum
Female - labia majora
Figure External genitalia of bisexual stage of human embryo.

37. Differentiation of Sexual Structures in Mammals (cont.)
Mesonephric duct
Male - vas deferens
Female - Gartner’s duct
Muellerian duct
Male - portions are retained
Female - reproductive tract
Figure Changes in female, mammalian urogenital system.

38. Differentiation of Sexual Structures in Mammals (cont.)
Mesonephric tubule
Male - vasa efferentia
Female - epoophoran and paraophoran
Genital ridge
Male - testes
Female - ovaries

39. Homologous Urogenital Structures
Figure Homologous urogenital structures in male and female mammals.

40. Mechanism for Elimination of Nitrogenous Wastes
Figure Nitrogenous
waste excretion (book figure 14.11).