DOCSLIB.ORG

Urogenital Sinus Also Take Part in the Development of the Urogenital System

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Urogenital Sinus Also Take Part in the Development of the Urogenital System LESSON 9 DEVELOPMENT OF GENITOURINARY SYSTEM Objectives By the end of this lesson, you should be able to: - 1. Describe the origin of the urogenital system 2. Describe the development of the male and female urinary system 3. Describe the development of the male and the female gonads 4. Describe the development of the male and the female accessory structures of reproduction 5. Describe the development of the male and the female external genitalia Introduction The urogenital system can be divided functionally into the urinary system and the genital system. • Embryologically and anatomically, however, they are closely connected. • The urogenital system develops from the intermediate mesoderm which extends along the dorsal body wall of the embryo. • The intermediate mesoderm later loses its connection with the somites and forms a longitudinal elevation of the mesoderm called the urogenital ridge. • Part of the urogenital ridge giving rise to the urinary tract is known as the nephrogenic cord. • The medial part of the urogenital ridge forms the gonadal (genital) ridge. • The mesothelial lining of the peritoneal cavity and the endoderm of the urogenital sinus also take part in the development of the urogenital system. Urogenital ridge 1. Gut 2. Gonad 3. Bowman's capsule 4. Mesonephric duct 5. Excretory tubule of mesonephros 6. Glomerulus 7. Mesentery URINARY SYSTEM KIDNEY • During the intrauterine life, three separate excretory systems arise successively. 1. The pronephros - This is nonfunctional and undergoes complete regression soon after its formation. 2. The mesonephros - serves as a temporary excretory organ. The body of the mesonephros undergoes degenerative changes, but caudal parts of the mesonephric tubules and mesonephric duct persist in the male. 3. The metanephros – This is a definitive structure Pronepros 1. Nephrotomes 2. Pronephric tubuli 3. Pronephric duct Mesonepros 1. Excretory units 2. Mesonephric duct 3. Nephrogenic cord Metanephros 1. Cloaca 2. Metanephric mesoderm 3. Ureteric bud PRONEPHROS The pronephros appears early in the fourth week as segmentally arranged cell (nephrotomes) and tubular (pronephric tubuli) structures in the cervical region of the intermediate mesoderm. The pronephric tubules open into the intraembryonic coelom (coelomic cavity), while the pronephric duct runs caudally and opens into the cloaca. By the beginning of the 5th week, the regression of the vestigial nephrotomes is complete. Pronepros 1. Pronephric tubule 2. Glomerulus 3. Dorsal aorta 4. Splanchnic mesoderm 5. Somatic mesoderm 6. Intraembryonic cavity 7. Neural tube 8. Yolk sac 9. Endoderm MESONEPROS • Late in the 4th week, caudal to the rudimentary pronephros. • The nephrogenic cord, from the first thoracic to the third lumbar segment, differentiates into mesonephric vesicles which elongate to form an S-shaped loops (tubules). • At their medial end, Bowman's capsule forms a mesonephric (renal) corpuscle together with the glomerulus. • At the opposite end, the tubules enter the mesonephric (Wolffian) duct. • Some parts of the mesonephric (Wolffian) duct do not completely disappear, but they persist in the male as the epididymis duct, ductus deferens, seminal vesicle and ejaculatory duct. • Also, some of the mesonephric tubules near the gonad persists in the male as the efferent ductules of the testis. Mesonepros 1. Gut 2. Gonad 3. Bowman's capsule 4. Mesonephric duct 5. Excretory tubule of mesonephros 6. Glomerulus 7. Mesentery Mesonephros and developing gonad 1. Gonad 2. Interstinal loop 3. Mesonephric duct 4. Neural tube 5. Mesonephros METANEPHROS • The definitive kidney or metanephros originates from two mesodermal rudiments: the ureteric bud (metanephric diverticulum) and the metanephric mesoderm (metanephrogenic blastema). • The collecting system develops from the ureteric bud, a dorsal outgrowth of the mesonephric (Wolffian) duct close to its entrance into the cloaca. • The bud penetrates the metanephric mesoderm forming the ampulla, which undergoes a series of repeated bifurcations. • The ureteric bud gives rise to the ureter, renal pelvis, major and minor calyces and collecting tubules within the kidney. Development of the renal pelvis • Metanephric mesoderm develops from the sacral portion of the nephrogenic cord. • Under the inductive influence of the ampulla, the metanephric mesoderm differentiates into renal vesicles and than into S-shaped tubules. • The tubules give rise to the excretory parts of the metanephros, called nephrons. • A nephron consists of the Bowman's capsule, the proximal convoluted tubule, the loop of Henle, and the distal convoluted tubule. Development of the renal pelvis 1 . Metanephric mesoderm 2 . Ureteric bud Development of the renal pelvis 1. Metanephric mesoderm 2. Ureteric bud 3. Pelvis 4. Major calyx Development of the renal pelvis 1. Metanephric mesoderm 2. Ureteric bud 3. Minor calyses 4. Pelvis Development of the nephron 1. Metanephric tissue cups 2. Ampulla 3. Collecting tubule 4. Metanephric mesoderm Development of the nephron 1. Metanephric tissue cups 2. Cell clusters 3. Renal vesicle 4. Collecting tubule Development of the nephron 1. Proximal convoluted tubule 2. Bowman's capsule 3. Metanephric mesoderm 4. Collecting tubule Development of the nephron 1. Bowman's capsule 2. Distal convoluted tubule 3. Collecting tubules Development of the nephron 1. Distal convoluted tubule 2. Glomerulus 3. Collecting tubules 4. Proximal convoluted tubule 5. Henle's loop 6. Bowman's capsule Development of the metanephros • The metanephros originates in the pelvic region. • Between the 6th to 8th week of the development, the metanephros ascends to the lumbar region, because of the disproportionate growth of the lumbar and sacral region. • During the kidney ascent to the abdominal level it rotates medially almost 90º. • Initially, the kidney hilum faces ventrally, but is finally directed anteromedially after the ascent and rotation. Ascent of the kidney 1. Urogenital ridge 2. Genital ridge 3. Mesonephric duct 4. Mesonephros 5. Gonad 6. Metanephric tissue 7. Ureter 8. Cloacal membrane 9. Cloaca 10. Allantois 11. Urorectal septum 12. Tail Ascent of the kidney 1. Mesonephric duct 2. Mesonephros 3. Gonad 4. Metanephros 5. Ureter 6. Cloacal membrane 7. Cloaca 8. Urorectal septum 9. Urogenital sinus 10. Anorectal canal 11. Tail Ascent of the kidney 1 . Ureter 2 . Metanephros 3 . Gonad 4 . Mesonephric duct 5 . Anal membrane 6 . Urogenital membrane 7 . Perineal body 8 . Bladder 9 . Rectum URETER, URINARY BLADDER AND THE URETHRA • The ureters develop from the caudal portion of the ureteric bud. • The urinary bladder and urethra are derived from the primitive urogenital sinus (a ventral part of the cloaca) and adjacent splanchnic mesenchyme. • The cloaca, the terminal portion of the hindgut is divided into the dorsal primitive rectum and ventral primitive urogenital sinus by the growth of the urorectal septum. • The same septum also divides cloacal membrane into the urogenital membrane anteriorly, and the anal membrane posteriorly. Development of urogenital sinus 1. Mesonephric duct 2. Mesonephros 3. Gonad 4. Metanephros 5. Ureter 6. Cloacal membrane 7. Cloaca 8. Urorectal septum 9. Urogenital sinus 10. Anorectal canal 11. Tail Formation of the urogenital sinus 1 . Ureter 2 . Metanephros 3 . Gonad 4 . Mesonephric duct 5 . Anal membrane 6 . Urogenital membrane 7 . Perineal body 8 . Bladder 9 . Rectum Development of the urinary bladder • The urogenital sinus gives rise to the urinary bladder, which is cranially continuous with allantois (later urachus) and caudally with the urethra. • During division of the cloaca the caudal portions of the mesonephric ducts are incorporated into the wall of the urinary bladder thus forming the trigone of the bladder. • The ureters and mesonephric ducts with time obtain the separate entrances into the urinary bladder. • In the male, the pelvic part of the urogenital sinus gives rise to the prostatic and membranous part of the urethra. • The penile urethra is partly formed by the closure of urethral folds, while its most distal portion is formed by an inward penetration of ectodermal cells on the tip of the glans. Development of the bladder and ureters 1. Ureter 2. Mesonephric duct 3. Urinary bladder Development of the bladder and ureters 1. Ureter 2. Mesonephric duct 3. Urinary bladder GENITAL SYSTEM • The genital system consists of the gonads, associated genital ducts and external genitalia. • Although the genetic sex of an embryo is determined at the time of fertilization, male and female genital systems are similar until the 7th week of the development (indifferent gonads stage). GONADS The gonads (testes and ovaries) are derived from three sources: - 1. The mesothelium (coelomic epithelium) lining the posterior abdominal wall 2. The underlying gonadal ridge mesenchyme 3. The primordial germ cells (precursors of spermatogonia or oogonia). Urogenital ridge 1. Gut 2. Gonadal ridge mesenchyme 3. Bowman’s capsule 4. Excretory tubule of mesonepros 5. Longitudinal mesonephric duct 6. Glumerulus 7. Mesentry Development of the gonads • The primordial germ cells first appear in the wall of the yolk sac in the 6th week and migrate along the dorsal mesentery of the hindgut to the genital ridges. • Genital ridges form a thickened area comprising mesothelium and underlying mesenchyme on the medial side of the mesonephros. • Epithelium of the genital ridge proliferates and penetrates the underlying mesenchyme, forming the primitive sex cords. Indifferent gonad 1. Coelomic epithelium
Load more

Recommended publications
  • Te2, Part Iii
    TERMINOLOGIA EMBRYOLOGICA Second Edition International Embryological Terminology FIPAT The Federative International Programme for Anatomical Terminology A programme of the International Federation of Associations of Anatomists (IFAA) TE2, PART III Contents Caput V: Organogenesis Chapter 5: Organogenesis (continued) Systema respiratorium Respiratory system Systema urinarium Urinary system Systemata genitalia Genital systems Coeloma Coelom Glandulae endocrinae Endocrine glands Systema cardiovasculare Cardiovascular system Systema lymphoideum Lymphoid system Bibliographic Reference Citation: FIPAT. Terminologia Embryologica. 2nd ed. FIPAT.library.dal.ca. Federative International Programme for Anatomical Terminology, February 2017 Published pending approval by the General Assembly at the next Congress of IFAA (2019) Creative Commons License: The publication of Terminologia Embryologica is under a Creative Commons Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0) license The individual terms in this terminology are within the public domain. Statements about terms being part of this international standard terminology should use the above bibliographic reference to cite this terminology. The unaltered PDF files of this terminology may be freely copied and distributed by users. IFAA member societies are authorized to publish translations of this terminology. Authors of other works that might be considered derivative should write to the Chair of FIPAT for permission to publish a derivative work. Caput V: ORGANOGENESIS Chapter 5: ORGANOGENESIS
    [Show full text]
  • Structure of Pronephros and Development of Mesonephric Kidney in Larvae of Russian Sturgeon, Acipenser Gueldenstaedtii Brandt (Acipenseridae)
    Zoologica5 PRONEPHROS Poloniae-AND (2012)-MESONEPHRIC 57/1-4: 5-20-KIDNEY-IN-LARVAE-OF-A.-GUELDENSTAEDTII 5 DOI: 10.2478/v10049-012-0001-6 STRUCTURE OF PRONEPHROS AND DEVELOPMENT OF MESONEPHRIC KIDNEY IN LARVAE OF RUSSIAN STURGEON, ACIPENSER GUELDENSTAEDTII BRANDT (ACIPENSERIDAE) L.S. KRAYUSHKINA*1, A.A. GERASIMOV1, A.A. KIRSANOV1, M.V. MOSYAGINA1, A. OGORZA£EK2 1Department of Ichthyology and Hydrobiology, St. Petersburg State University, 16-th Line 29, 199178, St. Petersburg, Russia, [email protected] 2 Department of Animal Developmental Biology, Zoological Institute, University of Wroclaw, Sienkiewicza 21, 50-335 Wroclaw, Poland. *Corresponding author Abstract. The structure of the pronephros and development of mesonephric kidney in Russian sturgeon larvae, Acipenser gueldenstaedtii Brandt at different stages of early postembryonic development (from hatching to 14 days), were studied with histological and electronic microscopy methods. The larval pronephros is represented by the system of bilaterally located pronephric tubules with ciliated nephrostomes and funnels and exog- enous single glomus, which is not integrated directly into pronephric tubules and located in the pronephric chamber. The glomus is positioned below the dorsal aorta and vascular- ized by its capillaries. The glomus has the same features of the thin structure that are typical of and necessary for the function of a filtering organ. The structure of the prone- phros in acipenserids is discussed and compared with teleosts and amphibians. Histogen- esis of the mesonephric kidney is observed during the period of pronephros functioning; it is complete by the time the larvae transfer to exogenous feeding. At this moment, the pronephros undergoes significant structural degradation.
    [Show full text]
  • Stem Cells in the Embryonic Kidney R Nishinakamura1
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector http://www.kidney-international.org mini review & 2008 International Society of Nephrology Stem cells in the embryonic kidney R Nishinakamura1 1Division of Integrative Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, 2-2-1 Honjo, Kumamoto, Japan The mammalian kidney, the metanephros, is formed by a STRATEGY TOWARD KIDNEY RECONSTITUTION USING reciprocally inductive interaction between two precursor PROGENITOR CELLS tissues, the metanephric mesenchyme and the ureteric bud. Stem cells are defined by two criteria: self-renewal and The ureteric bud induces the metanephric mesenchyme to multipotency. Few reports in the kidney field have addressed differentiate into the epithelia of glomeruli and renal tubules. both of these criteria at a clonal level, so it is better to use the Multipotent renal progenitors that form colonies upon Wnt4 term ‘progenitor’ rather than ‘stem cells.’ In this review, renal stimulation and strongly express Sall1 exist in the progenitors in the embryonic kidney, not those in the adult metanephric mesenchyme; these cells can partially kidney, from the viewpoint of developmental biology and reconstitute a three-dimensional structure in an organ stem/progenitor cell biology will be discussed. To generate culture setting. Six2 maintains this mesenchymal progenitor multiple cell lineages for kidney regeneration, the identifica- population by opposing Wnt4-mediated epithelialization. tion of renal progenitors is a prerequisite. Furthermore, there Upon epithelial tube formation, Notch2 is required for the exist three obstacles to be overcome: (1) derivation of the differentiation of proximal nephron structures (podocyte and renal progenitors; (2) expansion of the renal progenitors; and proximal tubules).
    [Show full text]
  • The Reproductive System
    27 The Reproductive System PowerPoint® Lecture Presentations prepared by Steven Bassett Southeast Community College Lincoln, Nebraska © 2012 Pearson Education, Inc. Introduction • The reproductive system is designed to perpetuate the species • The male produces gametes called sperm cells • The female produces gametes called ova • The joining of a sperm cell and an ovum is fertilization • Fertilization results in the formation of a zygote © 2012 Pearson Education, Inc. Anatomy of the Male Reproductive System • Overview of the Male Reproductive System • Testis • Epididymis • Ductus deferens • Ejaculatory duct • Spongy urethra (penile urethra) • Seminal gland • Prostate gland • Bulbo-urethral gland © 2012 Pearson Education, Inc. Figure 27.1 The Male Reproductive System, Part I Pubic symphysis Ureter Urinary bladder Prostatic urethra Seminal gland Membranous urethra Rectum Corpus cavernosum Prostate gland Corpus spongiosum Spongy urethra Ejaculatory duct Ductus deferens Penis Bulbo-urethral gland Epididymis Anus Testis External urethral orifice Scrotum Sigmoid colon (cut) Rectum Internal urethral orifice Rectus abdominis Prostatic urethra Urinary bladder Prostate gland Pubic symphysis Bristle within ejaculatory duct Membranous urethra Penis Spongy urethra Spongy urethra within corpus spongiosum Bulbospongiosus muscle Corpus cavernosum Ductus deferens Epididymis Scrotum Testis © 2012 Pearson Education, Inc. Anatomy of the Male Reproductive System • The Testes • Testes hang inside a pouch called the scrotum, which is on the outside of the body
    [Show full text]
  • Development of the Urogenital System of the Dog
    DEVELOPMENT OF THE UROGENITAL SYSTEM OF THE DOG MAJID AHMED AL-RADHAWI LICENCE, Higher Teachers' Training College, Baghdad, Iraq, 1954 A. THESIS submitted in partial fulfillment of the requirements for the degree MASTER OF SCIENCE Department of Zoology KANSAS STATE COLLEGE OF AGRICULTURE AND APPLIED SCIENCE 1958 LD C-2- TABLE OF CONTENTS INTRODUCTION AND HEVIEW OF LITERATURE 1 MATERIALS AND METHODS 3 OBSERVATIONS 5 Group I, Embryos from 8-16 Somites 5 Group II, Embryos from 17-26 Somites 10 Group III, Embryos from 27-29 Somites 12 Group 17, Embryos from 34-41 Somites 15 Group V , Embryos from 41-53 Somites 18 Subgroup A, Embryos from 41-<7 Somites 18 Subgroup B, Embryos from 4-7-53 Somites 20 Group VI, Embryos Showing Indifferent Gonad 22 Group VII, Embryos with Differentiatle Gonad 24 Subgroup A, Embryos with Seoondarily Divertioulated Pelvis ... 25 Subgroup B, Embryos with the Anlagen of the Uriniferous Tubules . 26 Subgroup C, Embryos with Advanced Gonad 27 DISCUSSION AND GENERAL CONSIDERATION 27 Formation of the Kidney .... 27 The Pronephros 31 The Mesonephros 35 The Metanephros 38 The Ureter 39 The Urogenital Sinus 4.0 The Mullerian Duot 40 The Gonad 41 1 iii TABLE OF CONTENTS The Genital Ridge Stage 41 The Indifferent Stage , 41 The Determining Stage, The Testes . 42 The Ovary 42 SUMMARI , 42 ACKNOWLEDGMENTS 46 LITERATURE CITED 47 APJENDEC 51 j INTRODUCTION AND REVIEW OF LITERATURE Nephrogenesis has been adequately described in only a few mammals, Buchanan and Fraser (1918), Fraser (1920), and MoCrady (1938) studied nephrogenesis in marsupials. Keibel (1903) reported on studies on Echidna Van der Strioht (1913) on the batj Torrey (1943) on the rat; and Bonnet (1888) and Davles and Davies (1950) on the sheep.
    [Show full text]
  • Glomus Specification and Induction in Xenopus
    Development 126, 5847-5856 (1999) 5847 Printed in Great Britain © The Company of Biologists Limited 1999 DEV6378 The specification and growth factor inducibility of the pronephric glomus in Xenopus laevis Hannah C. Brennan, Sarbjit Nijjar and Elizabeth A. Jones* Cell and Molecular Development Group, Department of Biological Sciences, Warwick University, Coventry, CV4 7AL, UK *Author for correspondence (e-mail: [email protected]) Accepted 23 September; published on WWW 24 November 1999 SUMMARY We report a study on the specification of the glomus, the Furthermore, we have analysed the growth factor filtration device of the amphibian pronephric kidney, using inducibility of the glomus in the presence or absence of an explant culturing strategy in Xenopus laevis. Explants of retinoic acid (RA) by RT-PCR. We define for the first time presumptive pronephric mesoderm were dissected from the conditions under which these growth factors induce embryos of mid-gastrula to swimming tadpole stages. These glomus tissue in animal cap tissue. Activin together with explants were cultured within ectodermal wraps and high concentrations of RA can induce glomus tissue from analysed by RT-PCR for the presence of the Wilm’s Tumour- animal cap ectoderm. Unlike the pronephric tubules, the 1 gene, xWT1, a marker specific for the glomus at the stages glomus can also be induced by FGF and RA. analysed, together with other mesodermal markers. We show that the glomus is specified at stage 12.5, the same stage at which pronephric tubules are specified. We have previously shown that pronephric duct is specified somewhat later, at stage 14.
    [Show full text]
  • Cranial Cavitry
    Embryology Endo, Energy, and Repro 2017-2018 EMBRYOLOGY OF THE REPRODUCTIVE SYSTEM Janine Prange-Kiel, Ph.D. Office: L1.106, Phone: 83117 Email: [email protected] LEARNING OBJECTIVES: • Name the structures in kidney development that contribute to the development of the reproductive organs. • Predict how the presence or absence of the Y chromosome and the expression of the SRY gene would influence the development of the gonads. • Predict how the presence or absence of testosterone, dihydrotestosterone, and anit- Mullerian hormone would influence the development of the genital ducts and indifferent primordia of the external genitalia. I. Introduction In general, the function of the genital (reproductive) system in males and females is the formation, nurture, and transport of germ cells. In females, an additional function is to provide the proper milieu for the fetal development after conception. Like the urinary system, the genital system derives from intermediate mesoderm. The development of these two systems is tightly interwoven as structures that develop as parts of the urinary system gain function in the genital system. In the adult, the sexual organs differ between males and females. The early genital system, however, is similar in both sexes, and the sexual differentiation of this initially indifferent, bipotential system starts only in the seventh week of embryonic development. The details on how sexual differentiation is determined will be discussed below, but it is worth mentioning here that irregularities in this process result in disorders of sexual differentiation (DSDs). DSDs occur in approximately 1 in 4,500 live births and will be discussed in a separate lecture.
    [Show full text]
  • Short Communication Clinical and Pathological
    Reprod Dom Anim 45, 368–372 (2010); doi: 10.1111/j.1439-0531.2009.01495.x ISSN 0936-6768 Short Communication Clinical and Pathological Findings of a Sac-like Formation in the Tunica Vaginalis of a Nelore (Bos indicus) Bull J Chaco´n1 and A Berrocal2,* 1Section of Andrology, Research Program on Applied Animal Andrology; 2Department of Pathology, School of Veterinary Medicine, Universidad, Nacional (UNA), Heredia, Costa Rica Contents and abnormalities in the ejaculate compared with A seven-month-old purebred Nelore calf was diagnosed with a normal bulls (Chaco´n et al. 1999; Chaco´n 2001). bilateral finger-shaped swelling although more prominent at Regarding the tunica vaginalis in the bull, abnormal- the left side of the scrotum, located longitudinal and parallel to ities reported in this serosa are mainly limited to epididymis corpus. The finding was present from 7 months of conditions such as hydrocele and adherences within age up to castration (performed at 25 months of age). Scrotal tunica layers secondary to orchitis. Blom and Christen- circumference, testicular and epididymis consistency and sen (1958) described also the presence of cyst like symmetry as well as seminal quality were normal during the formations (paradidymis), in the funiculus spermaticus follow-up period. The ultrasonographic appearance of the scrotal wall, pampiniform plexus, gonad and epididymis was (mesorchium), presumable derived from remnants of the normal. However, an anechoic region surrounded by a wall mesonephric duct. It is unknown that sac-like forma- forming a sac-like structure with a blind end at its dorsal pole tions in the tunica vaginalis of the bull or any other was seen on the swelling area.
    [Show full text]
  • Urinary System Intermediate Mesoderm
    Urinary System Intermediate mesoderm lateral mesoderm: somite ectoderm neural NOTE: Intermediate mesoderm splanchnic groove somatic is situated between somites and lateral mesoderm (somatic and splanchnic mesoderm bordering the coelom). All mesoderm is derived from the primary mesen- intermediate mesoderm endoderm chyme that migrated through the notochord coelom (becomes urogenital ridge) primitive streak. Intermediate mesoderm (plus adjacent mesothelium lining the coelom) forms a urogenital ridge, which consists of a laterally-positioned nephrogenic cord (that forms kidneys & ureter) and a medially-positioned gonadal ridge (for ovary/testis & female/male genital tract formation). Thus urinary & genital systems have a common embryonic origin; also, they share common ducts. NOTE: Urine production essentially requires an increased capillary surface area (glomeruli), epithelial tubules to collect plasma filtrate and extract desirable constituents, and a duct system to convey urine away from the body. Kidneys Bilateraly, three kid- mesonephric duct neys develop from the neph- metanephros pronephros rogenic cord. They develop mesonephric tubules chronologically in cranial- mesonephros caudal sequence, and are designated pro—, meso—, Nephrogenic Cord (left) and meta—, respectively. cloaca The pronephros and mesonephros develop similarly: the nephrogenic cord undergoes seg- mentation, segments become tubules, tubules drain into a duct & eventually tubules disintegrate. spinal ganglion 1] Pronephros—consists of (7-8) primitive tubules and a pronephric duct that grows caudally and terminates in the cloaca. The tubules soon degenerate, but the pronephric duct persists as the neural tube mesonephric duct. (The pronephros is not functional, somite except in sheep.) notochord mesonephric NOTE tubule The mesonephros is the functional kidney for fish and am- aorta phibians. The metanephros is the functional kidney body of reptiles, birds, & mammals.
    [Show full text]
  • The Derivatives of Three-Layered Embryo (Germ Layers)
    HUMANHUMAN EMBRYOLOGYEMBRYOLOGY Department of Histology and Embryology Jilin University ChapterChapter 22 GeneralGeneral EmbryologyEmbryology FourthFourth week:week: TheThe derivativesderivatives ofof trilaminartrilaminar germgerm discdisc Dorsal side of the germ disc. At the beginning of the third week of development, the ectodermal germ layer has the shape of a disc that is broader in the cephalic than the caudal region. Cross section shows formation of trilaminar germ disc Primitive pit Drawing of a sagittal section through a 17-day embryo. The most cranial portion of the definitive notochord has formed. ectoderm Schematic view showing the definitive notochord. horizon =ectoderm hillside fields =neural plate mountain peaks =neural folds Cave sinks into mountain =neural tube valley =neural groove 7.1 Derivatives of the Ectodermal Germ Layer 1) Formation of neural tube Notochord induces the overlying ectoderm to thicken and form the neural plate. Cross section Animation of formation of neural plate When notochord is forming, primitive streak is shorten. At meanwhile, neural plate is induced to form cephalic to caudal end, following formation of notochord. By the end of 3rd week, neural folds and neural groove are formed. Neural folds fuse in the midline, beginning in cervical region and Cross section proceeding cranially and caudally. Neural tube is formed & invade into the embryo body. A. Dorsal view of a human embryo at approximately day 22. B. Dorsal view of a human embryo at approximately day 23. The nervous system is in connection with the amniotic cavity through the cranial and caudal neuropores. Cranial/anterior neuropore Neural fold heart Neural groove endoderm caudal/posterior neuropore A.
    [Show full text]
  • Embryology of the Kidney Rizaldy Paz Scott | Yoshiro Maezawa | Jordan Kreidberg | Susan E
    1 Embryology of the Kidney Rizaldy Paz Scott | Yoshiro Maezawa | Jordan Kreidberg | Susan E. Quaggin CHAPTER OUTLINE MAMMALIAN KIDNEY DEVELOPMENT, 2 MOLECULAR GENETICS OF MODEL SYSTEMS TO STUDY KIDNEY NEPHROGENESIS, 22 DEVELOPMENT, 8 GENETIC ANALYSIS OF MAMMALIAN KIDNEY DEVELOPMENT, 15 KEY POINTS • The development of the kidney relies on reciprocal signaling and inductive interactions between neighboring cells. • Epithelial cells that comprise the tubular structures of the kidney are derived from two distinct cell lineages: the ureteric epithelia lineage that branches and gives rise to collecting ducts and the nephrogenic mesenchyme lineage that undergoes mesenchyme to epithelial transition to form connecting tubules, distal tubules, the loop of Henle, proximal tubules, parietal epithelial cells, and podocytes. • Nephrogenesis and nephron endowment requires an epigenetically regulated balance between nephron progenitor self-renewal and epithelial differentiation. • The timing of incorporation of nephron progenitor cells into nascent nephrons predicts their positional identity within the highly patterned mature nephron. • Stromal cells and their derivatives coregulate ureteric branching morphogenesis, nephrogenesis, and vascular development. • Endothelial cells track the development of the ureteric epithelia and establish the renal vasculature through a combination of vasculogenic and angiogenic processes. • Collecting duct epithelia have an inherent plasticity enabling them to switch between principal and intercalated cell identities. MAMMALIAN KIDNEY DEVELOPMENT The filtration function of the kidneys is accomplished by basic units called nephrons (Fig. 1.1). Humans on average have 1 million nephrons per adult kidney but the range of ANATOMIC OVERVIEW OF THE 4 MAMMALIAN KIDNEY total nephrons is highly variable across human populations. Each mouse kidney may contain up to 12,000–16,000 nephrons The kidney is a sophisticated, highly vascularized organ that depending on the strain.5 This wide range in nephron number plays a central role in overall body homeostasis.
    [Show full text]
  • Nephric Lineage Specification by Pax2 and Pax8
    Downloaded from genesdev.cshlp.org on September 28, 2021 - Published by Cold Spring Harbor Laboratory Press Nephric lineage specification by Pax2 and Pax8 Maxime Bouchard, Abdallah Souabni, Markus Mandler, Annette Neubüser, and Meinrad Busslinger1 Research Institute of Molecular Pathology, Vienna Biocenter, A-1030 Vienna, Austria The mammalian kidney develops in three successive steps from the initial pronephros via the mesonephros to the adult metanephros. Although the nephric lineage is specified during pronephros induction, no single regulator, including the transcription factor Pax2 or Pax8, has yet been identified to control this initial phase of kidney development. In this paper, we demonstrate that mouse embryos lacking both Pax2 and Pax8 are unable to form the pronephros or any later nephric structures. In these double-mutant embryos, the intermediate mesoderm does not undergo the mesenchymal-epithelial transitions required for nephric duct formation, fails to initiate the kidney-specific expression of Lim1and c -Ret, and is lost by apoptosis 1d after failed pronephric induction. Conversely, retroviral misexpression of Pax2 was sufficient to induce ectopic nephric structures in the intermediate mesoderm and genital ridge of chick embryos. Together, these data identify Pax2 and Pax8 as critical regulators that specify the nephric lineage. [Keywords: Pax2;Pax8;genetic redundancy;kidney development;mesenchymal-epithelial transition;lineage specification] Received June 28, 2002;revised version accepted September 20, 2002. Kidney development in mammals and birds proceeds in development (for review, see Kuure et al. 2000;Davies three successive steps that are all characterized by the and Brändli 2002). The majority of these genes are essen- mesenchymal-to-epithelial transformation of intermedi- tial for proper morphogenesis of the metanephros with ate mesoderm cells.
    [Show full text]