Comparative AnatomyComparative AnatomyUrogenital SystemUrogenital System

KardongKardongChapter 14Chapter 14

Part 14 Part 14

Urogenital SystemUrogenital System Ducts of excretory and reproductive Ducts of excretory and reproductive

systems are intimately associated systems are intimately associated with each otherwith each other

Figure 14.2. Evolutionary development of kidneys in vertebrates.

Figure 14.1. Embryonic origin of the kidneys (book figure 14.4).

Primitive KidneyPrimitive Kidney Archinephros- primitive excretory kidney Archinephros- primitive excretory kidney

organorgan Holonephric concept - (3 kidneys are a part Holonephric concept - (3 kidneys are a part

of one organ)of one organ) Filtration systemFiltration system Archinephric duct- drains to cloaca or Archinephric duct- drains to cloaca or

bladderbladder

Figure 14.3. Hypothetical archinephros.

Primitive Kidney Primitive Kidney (cont.)(cont.) Pronephros Pronephros

11stst tubules to appear tubules to appear Anteriorly located; head kidneyAnteriorly located; head kidney Involutes to form lymphoidal massInvolutes to form lymphoidal mass Only functions temporarily Only functions temporarily

All tubules associated with pronephrosAll tubules associated with pronephros Pronephric (archinephric) duct drains pronephrosPronephric (archinephric) duct drains pronephros

Figure 14.5. Pronephros – anterior region of primitive kidney.

Figure 14.4. Three-part kidney (book figure 14.5).

Figure 14.6. Fate of nephrogenic mesoderm (red).

Kidney Structure Kidney Structure (cont.)(cont.)

Figure 14.7. Pronephric, mesonephric, and metanephric system relationships (see book figure 14.6).

Kidney Structure Kidney Structure (cont.)(cont.) Mesonephros (opisthonephros)- kidney Mesonephros (opisthonephros)- kidney

mass caudal to pronephric regionmass caudal to pronephric region Functional adult kidney of fish and Functional adult kidney of fish and

amphibiansamphibians Opisthonephros - in most adult Opisthonephros - in most adult

amphibians and fishes.amphibians and fishes. Drained by mesonephric Drained by mesonephric

(archinephric) duct(archinephric) duct

Figure 14.9. Mesonephric duct of opossum embryo.

Figure 14.8. Mesonephros of urodeles (see book figure 14.8)

Urogenital Anatomy Urogenital Anatomy Ductus efferens:Ductus efferens:

Pronephric ductPronephric duct Mesonephric ductMesonephric duct Archinephric duct (= Archinephric duct (=

wolffian duct)wolffian duct) Anterior portion of Anterior portion of

mesonephric tubules used in mesonephric tubules used in male reproductive systemmale reproductive system

Figure 14.10. Urogenital system and adrenal glands of male frog.

Figure 14.11. Mesonephric kidneys with mesonephric duct (black) carrying sperm and/or urine (see book figure 14.24).

Urogenital Anatomy Urogenital Anatomy (cont.)(cont.)

Urogenital Anatomy Urogenital Anatomy (cont.)(cont.) Accessory urinary ductsAccessory urinary ducts

Tubules also in reproductive sys.Tubules also in reproductive sys. Path for sperm to enter mesonephric duct (sperm duct)Path for sperm to enter mesonephric duct (sperm duct)

Figure 14.12. Mesonephric kidneys with separate sperm duct (red) (see book figure 14.24).

Urogenital Anatomy Urogenital Anatomy (cont.)(cont.) Pronephros Pronephros

LostLost Mesonephros Mesonephros

Mainly an embryonic kidneyMainly an embryonic kidney Involutes at birthInvolutes at birth

Metanephric kidney Metanephric kidney Takes over functions of mesonephros Takes over functions of mesonephros Ureter- new duct drains meta. kidneyUreter- new duct drains meta. kidney

Figure 14.13. Metanephric kidney assuming superior position to remainder of urogenital system.

Urogenital Anatomy Urogenital Anatomy (cont.)(cont.)

Mesonephric ductMesonephric duct Sperm duct in malesSperm duct in males Ductus deferens in amphibiansDuctus deferens in amphibians Vas deferens in mammalsVas deferens in mammals

Terminate at cloacaTerminate at cloaca Most amniotesMost amniotes Not in higher vertebratesNot in higher vertebrates

Figure 14.14. Male teleost, caudal end of urogenital system.

Summary of Embryonic Amniote Summary of Embryonic Amniote Urogenital AnatomyUrogenital Anatomy

Pronephros involutesPronephros involutes Mesonephros involutesMesonephros involutes Metanephric kidney developsMetanephric kidney develops

Vas deferens (sperm duct in Vas deferens (sperm duct in mammals)mammals)

Table 1. Terminology ofthe urogenital system (bookFigure 14.21).

Urinary BladderUrinary Bladder Found in most vertebratesFound in most vertebrates Formation variesFormation varies

Fish- terminal segment of mesonephric ductFish- terminal segment of mesonephric duct Large bladders- turtles and lizardsLarge bladders- turtles and lizards

Turtles- accessory bladderTurtles- accessory bladder

Figure 14.15. Evolution of the urinary bladder (book figure 14.53).

GonadsGonads

Elevated ridges medial to kidneysElevated ridges medial to kidneys Gonads enlarge, suspended by Gonads enlarge, suspended by

mesenteriesmesenteries Mesorchium- malesMesorchium- males Mesovarium- femalesMesovarium- females

Figure 14.16. Urogenital ridge in developing embryo (book figure 14.18).

Figure 14.17. Ovary of hagfish (book figure 14.23).

GonadsGonads (cont.)(cont.)

Bidder’s organBidder’s organ Rudimentary ovary of toads (genusRudimentary ovary of toads (genusAnaxyrusAnaxyrus—formerly —formerly BufoBufo))

If testes removed, become If testes removed, become functional ovaryfunctional ovary

Ovotestes in fishOvotestes in fish Both ovary and testis in lizardsBoth ovary and testis in lizards Multi-lobed testis in some species of Multi-lobed testis in some species of

salamanders (genus salamanders (genus DesmognathusDesmognathus))

Figure 14.18. Left bidder’s organ of male Anaxyrus.

Male Urogenital System (cont.)

Figure 14.19. Urogenital anatomy of male fishes (book figure 14.33).

Male Urogenital System (cont.)

Figure 14.20. Urogenital anatomy of tetrapod males (book figure 14.35).

Figure 14.21. Urogenital anatomy of female fishes (book figure 14.25).

Female Gonads (cont.)

Female Gonads (cont.)

Figure 14.22. Urogenital anatomy of tetrapod females (book figure 14.27).

Copulatory OrgansCopulatory Organs

Claspers in cartilagenous fishClaspers in cartilagenous fish Gonopodium in teleostGonopodium in teleost Intromittent organ Intromittent organ

HemipenesHemipenes Single penisSingle penis

Figure 14.23. Gonopodium of a male guppy.

Figure 14.24. Intromittent organs in the chondrichthyans(book figure 14.38).

Copulatory Organs (cont’d.)

Copulatory Organs (cont.)

Figure 14.25. Intromittent organs in the turtles and crocodylians (book figure 14.42).

Copulatory Organs (cont.)

Figure 14.26. Intromittent organs in birds—domestic turkey (book figure 14.44).

Copulatory Organs (cont.)

Figure 14.27. Penis in the dog (book figure 14.45).

No copulatory organsNo copulatory organs Sperm pocket- Sperm pocket-

Spermatheca in most Spermatheca in most salamanderssalamanders

Rudimentary copulatory Rudimentary copulatory organorgan Some amniotes Some amniotes

(tuatara)(tuatara) Cloacal appositionCloacal apposition

Male and female Male and female cloacae come togethercloacae come together

CloacaCloaca Receives digestive, reproductive, and Receives digestive, reproductive, and

urinary products and tractsurinary products and tracts No cloacaNo cloaca

Fish – may have three separate openingsFish – may have three separate openings Lost in mammals above monotremesLost in mammals above monotremes

Cloaca subdivisions:Cloaca subdivisions: CoprodaeumCoprodaeum UrodaeumUrodaeum ProctodaeumProctodaeum

Figure 14.28. Cloacal cavities and urogenital structures in a salamander.

Cloacal SubdivisionsCloacal Subdivisions CoprodeumCoprodeum

Receives alimentary canalReceives alimentary canal Simple columnarSimple columnar

UrodeumUrodeum Receives urinary and Receives urinary and

reproductive productsreproductive products Transitional epitheliumTransitional epithelium

ProctodeumProctodeum Associated with excretoryAssociated with excretory Stratified squamousStratified squamous

Figure 14.29. Subdivisions of cloaca shown in a lizard.

Urogenital papilla

Cloacal gland

Ductus deferens

Ureter

Cloacal cavity

Sperm

Urogenital Papilla

Figure 14.30. Urogenital papilla in snakes.

• Typically found in chondrichthyans and squamates.

Cloacal Region of a Bird

Figure 14.31. Bird cloacae (book figure 14.49).

Bird Cloaca Bird Cloaca (cont.)(cont.)

Bursa of FabriciusBursa of Fabricius Lymphoid evagination off cloacaLymphoid evagination off cloaca

Figure 14.32. Bursa of Fabricius on young bird. Figure 14.33. Histology of

Bursa of Fabricius and cloaca.

Urogenital System Urogenital System (cont.)(cont.)

Figure 14.34. Urogenital systems of female tetrapods (book figure 14.28).

Urogenital System Urogenital System (cont.)(cont.)

Muellarian ductsMuellarian ducts In males, ducts are nonfunctionalIn males, ducts are nonfunctional In females, ducts give rise to female In females, ducts give rise to female

reproductive tractreproductive tract Only left reproductive tractOnly left reproductive tract

Birds and crocodiles Birds and crocodiles Raptors have vestigial right Raptors have vestigial right

reproductive tractreproductive tract

Figure 14.35. Book figures 14.25 and 14.27.

Reproductive Tracts of Mammals Reproductive Tracts of Mammals Duplex uterusDuplex uterus

Monotremes and marsupialsMonotremes and marsupials Separated female reproductive tractsSeparated female reproductive tracts

Bipartite uterusBipartite uterus RabbitRabbit Body of uterus seems unpaired, yet Body of uterus seems unpaired, yet

has two lumenshas two lumens Bicornuate uterusBicornuate uterus

CatCat Two uterine horns and single lumenTwo uterine horns and single lumen

Figure 14.36. Morphology of uteri (book figures 14.51-52).

Reproductive Tracts of Mammals Reproductive Tracts of Mammals (cont.)(cont.)

Bicornuate uterusBicornuate uterus CatCat Two uterine horns and single Two uterine horns and single

lumenlumen Simplex uterusSimplex uterus

PrimatesPrimates Large body and hornsLarge body and horns

Figures 14.37-38. Mammalian uteri; fused muellerian ducts (blackened regions) and cloaca (red).

ReproductionReproduction

Most vertebrates require both sexesMost vertebrates require both sexes Some vertebrates are asexualSome vertebrates are asexual

Reproduce parthenogeneticallyReproduce parthenogenetically Some fish and lizardsSome fish and lizards

Embryonic humans are asexualEmbryonic humans are asexual Until differentiation of sexual structuresUntil differentiation of sexual structures

Differentiation of Sexual StructuresDifferentiation of Sexual Structures

Figures 14.39-40. Mesonephros contributions to male and female reproductive tracts.

Differentiation of Sexual Structures in Differentiation of Sexual Structures in Mammals Mammals (cont.)(cont.)

Genital tubercleGenital tubercle Male - penisMale - penis Female - clitorisFemale - clitoris

Genital foldsGenital folds Male - penis contributionMale - penis contribution Female - labia minoraFemale - labia minora

Genital swellingsGenital swellings Male - scrotumMale - scrotum Female - labia majoraFemale - labia majora

Figure 14.41. External genitalia of bisexual stage of human embryo.

Differentiation of Sexual Structures in Differentiation of Sexual Structures in Mammals Mammals (cont.)(cont.)

Mesonephric ductMesonephric duct Male - vas deferensMale - vas deferens Female - Gartner’s ductFemale - Gartner’s duct

Muellerian ductMuellerian duct Male - portions are retainedMale - portions are retained Female - reproductive tractFemale - reproductive tract

Figure 14.42. Changes in female, mammalian urogenital system.

Mesonephric tubuleMesonephric tubule Male - vasa efferentiaMale - vasa efferentia Female - epoophoran and paraophoranFemale - epoophoran and paraophoran

Genital ridgeGenital ridge Male - testesMale - testes Female - ovariesFemale - ovaries

Differentiation of Sexual Structures in Differentiation of Sexual Structures in Mammals Mammals (cont.)(cont.)

Homologous Urogenital StructuresHomologous Urogenital Structures

Figure 14.43. Homologous urogenital structures in male and female mammals.

Mechanism for Elimination of Nitrogenous Wastes

Figure 14.44. Nitrogenouswaste excretion (book figure 14.11).