 Kidney = Nephrons dorsal to coelom.  Nephron = Tubular structure that reabsorbs substances from a coelomic fluid-derived or plasma-derived filtrate Urinary System

 Coelomic funnel = cilliated opening of nephron to coelom – where coelomic fluid enters the nephron  Bowman’s capsule = end of nephron that surrounds a mass of capillaries (Glomerulus) – where plasma enters the nephron  Concentrated fluid waste (urine) is formed that usually is rich in nitrogenous (e.g. urea, uric acid) waste. Nephron Structure

Human Kidney Development

 Intermediate mesoderm forms nephric tubules in nephric ridges.  Some remain contiguous with the coelom of the lateral plate mesoderm. Nephron Development int. mesoderm dorsal aorta coelom

Nephron Function

Vertebrate Embryo (section) neural crest cells dermatome sclerotome myotome splanchnic mesoderm somatic mesoderm gut lateral plate mesoderm inter- mediate meso- derm

Vertebrate Embryo (section) gut lateral plate mesoderm inter- mediate meso- derm neural crest cells dermatome sclerotome myotome splanchnic mesoderm somatic mesoderm

Vertebrate Embryo (section) gut coelom dermatome sclerotome myotome dorsal & ventral mesenteries (splanchnic mesoderm) lateral plate mesoderm inter- mediate meso- derm

Vertebrate Embryo (section) gut dermatome vertebra myotome horizontal septum dorsal & ventral mesenteries (splanchnic mesoderm) lateral plate mesoderm inter- mediate meso- derm coelom

Vertebrate Embryo (section) gut dermatome vertebra myotome horizontal septum dorsal mesentery (splanchnic mesoderm) lateral plate mesoderm inter- mediate meso- derm coelom

Nephron Development

 Nephric ridges  Pronephros = Segmental; develops 1 st ; coelomic funnel (Lost in adults, except Myxini).  Mesonephros = Segmental; posterior to pronephros; coelomic funnel & Bowman’s capsule (Lost in adult amniotes).  Metanephros = Develop segmentally but obscured by nephron proliferation (but segmental in hagfishes) ; posterior to mesonephros; Bowman’s capsule. Kidney Regions

Vertebrate Mesoderm Lateral Plate Mesoderm Somites Somitomeres Intermediate Mesoderm

 Archinephric duct = Pronephros initiates formation; drains pro-, meso-, & sometimes meta-nephros.  Accessory duct = Develops longitudinally from the archinephric duct (in some elasmobrachs and salamanders) ; drains the meso- and meta-nephros.  Metanephric Duct (ureter) = Develops as bud from base of the archinephric duct; drains metanephros (Only in amniotes). Kidney Development

pronephros mesonephros meta- nephros Hagfish Kidney archinephric duct

pronephros mesonephros meta- nephros Opisthonephric Kidney archinephric duct accessory duct

pronephros mesonephros archinephric duct Metanephric Kidney meta- nephros

 Holonephric Kidney = pro-, meso-, and segmental meta-nephric tubules  Opisthonephric Kidney = mesonephric and metanephric tubules drained by archinephric and possibly accessory ducts.  Metanephric Kidney = composed only of non-segmental metanephric tubules; drained by metanephric duct (ureter). Adult Kidney Types

Human Kidney Development

Human Urinary

Adult Kidney GroupTypeTubules Myxini holonephric pro-, meso-, & meta- Petromyzontida opisthonephricmeso- & meta- Chondrichthys opisthonephricmeso- & meta- Actinopterygii opisthonephricmeso- & meta- Dipnoi opisthonephricmeso- & meta- Lissamphibia opisthonephricmeso- & meta- Mammalia metanephricmeta- Reptilia metanephricmeta-

Subphylum Vertebrata hagfishes lampreys sharks, rays, etc. Actinopterygii coelacanths lungfishes amphibians Mammalia Reptilia meta- nephric kidney; ureters function of pronephric tubules reduced opisthonephric kidney

 Ammonia = NH 4 +, toxic, excreted in large amounts by many aquatic organisms (not all). hagfishes, lampreys, Actinopterygii, lungfishes, coelacanths, amphib., crocodylians, aquatic turtles.  Urea = CO(NH 2 ), less toxic, gnathostomes (Actinopterygiians use it less, Chondrichthyians and Mammals most).  Uric Acid = C 4 O 3 N 4 H 3, less toxic, slightly soluble in water, precipitates in cloaca. Requires least amount of water to excrete. Only reptiles produce in large amounts. Nitrogenous Waste

Subphylum Vertebrata hagfishes lampreys sharks, rays, etc. Actinopterygii coelacanths lungfishes amphibians Mammalia Reptilia uric acid function of pronephric tubules reduced urea ancestrally ammonia

 Gonad = Organ that produces gametes and hormones.  Testis = Male gonad  Seminiferous tubules = site of sperm formation in testis.  Ovary = Female gonad  Follicle = Specialized cells that surround a developing ovum in the ovary.  Gamete = 1n sex cell (sperm/ ovum). Reproductive System

Gonadal Histology

 Indifferent gonad (Genital ridges) = the early gonad; neither testis nor ovary.  Germ cells = will form gametes. Migrate from endoderm via dorsal mesentery.  Primary Sex Cords = coelomic mesothelium of ridge grows into mesenchyme of ridge. ♂ primary sex cords  seminiferous tubules ♀ primary sex cords  form and disappear  Secondary Sex Cords = mesothelium again grows into mesenchyme of genital ridge. ♀ secondary sex cords  ovarian follicles Gonad Development

Vertebrate Embryo (section) gut dermatome vertebra myotome horizontal septum dorsal mesentery (splanchnic mesoderm) lateral plate mesoderm inter- mediate meso- derm coelom genital ridge

Gonad Development

 ALL Non-amniotes = archinephric ducts drain kidneys.  Amniotes = metanephric ducts drain kidneys.  Hagfishes & Lampreys = no testis ducts.  Gnathostomes = archinephric ducts drain the testes (also drain the kidneys in all non- amniote ganthostomes). EXCEPTION - Teleosts & Amia = new gonoduct drains testes (not the archinephric duct) Male Urogenital Ducts

Hagfish and Lamprey Male Ducts archi- nephric duct testis kidney abdominal pore

Male Genital Ducts (Non-amniote) archi- nephric duct testes kidney abdominal pore

Male Genital Ducts (Non-amniote) archi- nephric duct testes kidney abdominal pore

Male Genital Ducts (Amniote) archi- nephric duct testes kidney meta- nephric ducts

Male Genital Ducts (Teleost or Amia) archi- nephric duct testes kidney gonoduct

 ALL Non-amniotes = archinephric ducts drain kidneys.  Amniotes = metanephric ducts drain kidneys.  Hagfishes & lampreys = no ovary ducts.  Gnathostomes = Müllerian ducts open to the coelom capture ova. (archinephric ducts lost in female amniotes) In birds the right Müllerian duct is reduced and the right ovary is usually absent EXCEPTION - Teleosts & Amia = new gonoduct not open to coelom captures ova (not the Müllerian duct) Female Urogenital Ducts

Hagfish and Lamprey Female Ducts archi- nephric duct ovary kidney abdominal pore

Female Genital Ducts (Non-amniote) archi- nephric duct ovaries kidney abdominal pore Müllerian duct

Female Genital Ducts (Amniote) ovaries kidney meta- nephric ducts Müllerian duct

Female Genital Ducts (Teleost or Amia) archi- nephric duct ovaries kidney gonoduct

Female Genital Ducts Teleosts

Male Genital Ducts

Male Urogenital Ducts Groupfrom Kidneyfrom Testis Myxini archinephricnone Petromyzontida archinephricnone Chondrichthys accessory & arch. archinephric Polypter-, Ascipenser-, & Lepisosteiformes archinephric Teleostei & Amia archinephric male gonoduct Dipnoi archinephric Lissamphibia accessory & arch. archinephric Mammalia metanephricarchinephric Reptilia metanephricarchinephric

Female Urogenital Ducts Groupfrom Kidneyfrom Ovary Myxini archinephricnone Petromyzontida archinephricnone Chondrichthys archinephricMüllerian duct Polypter-, Ascipenser-, & Lepisosteiformes archinephricMüllerian duct Teleostei & Amia archinephric female gonoduct Dipnoi archinephricMüllerian duct Lissamphibia archinephricMüllerian duct Mammalia metanephricMüllerian duct Reptilia metanephricMüllerian duct

Subphylum Vertebrata hagfishes lampreys sharks, rays, etc. Actinopterygii coelacanths lungfishes amphibians Mammalia Reptilia archinephric duct lost in females; meta- nephric serves kidneys archinephric duct serves testes in males; Müllerian duct in females

sturgeons & paddlefishes gars bowfin (Amia) TELEOSTS bichirs & ropefishes Class Actinopterygii Müllerian duct lost; new gonoducts for ovary and testis

Amniota montremes marsupials eutherians turtles lizards & snakes crocodylians birds right ovary and oviduct (Müllerian) reduced or lost

 The human genitalia are sexually homologous developing from the “same” developmental precursors. Human Genitalia

Human Genital Development urinary reproductive Early MaleFemale tubercle glansglans penisclitoris folds scrotumlabia

Human Genitalia Development

Human Genital Intersexuality

Human Female Reproductive

Human Male Reproductive

 In both male and female humans the gonads move inferiorly, in males dramatically so into the scrotum. Gonadal Descent

Cryptorchidism

 Genitalia = external or extruded reproductive structures  Intromittent organ = structure for transfer of sperm to facilitate internal fertilization (but not necessary for it) ; Intromittent organs evolved repeatedly.  Internal fertilization: Chondrichthyans, Amniotes, & Miscellaneous others Comparative Vertebrate Genitalia

 Cloaca = (sewer in Latin) ectodermal, posterior chamber; intestine, urinary system, and reproductive system “empty” here.  Cloaca lost in Therian mammals, Actinopterygiians, and chimaeras. Separate, external anal and urogenital openings. Cloaca

Chondrichthyan Male Genitalia  Claspers = paired pelvic fin derived structures; grooved for sperm transfer.

 Amniotes ancestrally develop a genital tubercle. Homologous to glans penis and glans clitoris in mammals.  Genital tubercle often regresses in female non-mammalian amniotes.  Lepidosaurs and most birds have secondarily lost the genital tubercle. Amniote Genitalia

Amniote Genital Development urinary reproductive Early MaleFemale tubercle glansglans penisclitoris folds scrotumlabia

 Median penis = in amniotes; derived from genital tubercle; erectile tissue and a sulcus spermaticus (groove). Secondarily lost in lepidosaurs and most birds (ratites, ducks & geese retain) Mammals = closed sulcus spermaticus that in therians also extends the urethra Many mammals have a baculum (bone in the penis) Male Genitalia

Testudinean Male Genitalia

Crocodylian Genitalia

Rhea Male Genitalia

Monotreme Male Genitalia  Slightly forked penis (four-headed).  Testes remain abdominal (no scrotum). echidna penis

Therian Testes  Scrotum sac containing the testes outside of the male’s body.  Adult testes usually are in a scrotum or to under the skin’s surface.

Marsupial Genitalia  Forked penis in most male marsupials. (scrotum anterior to penis)  Paired vaginas in all female marsupials. sugar glider penis

Kangaroo Male Genitalia

Eutherian Genitalia  Simple penis in most male euterians. (scrotum posterior to penis)  Single vagina in all female eutherians.

Hyaena Genitalia two female hyaenas

Lepidosaur Male Genitalia  Hemipenes = paired cloacal structures; grooved for sperm transfer.

Subphylum Vertebrata hagfishes lampreys sharks, rays, etc. Actinopterygii coelacanths lungfishes amphibians Mammalia Reptilia cloaca cloaca lost genital tubercle; median penis & clitoris claspers

hemipenes; gen. tubercle lost Amniota montremes marsupials eutherians turtles lizards & snakes crocodilians birds genital tubercle lost in most genital tubercle - median penis & clitoris vagina(s); scrotum; cloaca lost (or reduced) sulcus sper- maticus closed (tubular) forked penis & paired vaginas