Mesoderm Divided Into Three Main Types - Paraxial (Somite) - Intermediate - Lateral (Somatic and Splanchnic)
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3 Embryology and Development
BIOL 6505 − INTRODUCTION TO FETAL MEDICINE 3. EMBRYOLOGY AND DEVELOPMENT Arlet G. Kurkchubasche, M.D. INTRODUCTION Embryology – the field of study that pertains to the developing organism/human Basic embryology –usually taught in the chronologic sequence of events. These events are the basis for understanding the congenital anomalies that we encounter in the fetus, and help explain the relationships to other organ system concerns. Below is a synopsis of some of the critical steps in embryogenesis from the anatomic rather than molecular basis. These concepts will be more intuitive and evident in conjunction with diagrams and animated sequences. This text is a synopsis of material provided in Langman’s Medical Embryology, 9th ed. First week – ovulation to fertilization to implantation Fertilization restores 1) the diploid number of chromosomes, 2) determines the chromosomal sex and 3) initiates cleavage. Cleavage of the fertilized ovum results in mitotic divisions generating blastomeres that form a 16-cell morula. The dense morula develops a central cavity and now forms the blastocyst, which restructures into 2 components. The inner cell mass forms the embryoblast and outer cell mass the trophoblast. Consequences for fetal management: Variances in cleavage, i.e. splitting of the zygote at various stages/locations - leads to monozygotic twinning with various relationships of the fetal membranes. Cleavage at later weeks will lead to conjoined twinning. Second week: the week of twos – marked by bilaminar germ disc formation. Commences with blastocyst partially embedded in endometrial stroma Trophoblast forms – 1) cytotrophoblast – mitotic cells that coalesce to form 2) syncytiotrophoblast – erodes into maternal tissues, forms lacunae which are critical to development of the uteroplacental circulation. -
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. -
Essential Roles of Inhibin Beta a in Mouse Epididymal Coiling
Essential roles of inhibin beta A in mouse epididymal coiling Jessica Tomaszewski*, Avenel Joseph†, Denise Archambeault†, and Humphrey Hung-Chang Yao†‡ *Department of Biology, School of Integrative Biology, and †Department of Veterinary Biosciences, College of Veterinary Medicine, University of Illinois at Urbana–Champaign, Urbana, IL 61802 Edited by Jean D. Wilson, University of Texas Southwestern Medical Center, Dallas, TX, and approved May 29, 2007 (received for review April 13, 2007) Testis-derived testosterone has been recognized as the key factor appear to be indirect via a mesenchyme-derived regulator(s). When for morphogenesis of the Wolffian duct, the precursor of several the upper Wolffian duct epithelium (the future epididymis) was male reproductive tract structures. Evidence supports that testos- grafted onto the lower Wolffian duct mesenchyme (the future terone is required for the maintenance of the Wolffian duct via its seminal vesicle), the epithelium underwent seminal vesicle mor- action on the mesenchyme. However, it remains uncertain how phogenesis and expressed markers specific for seminal vesicle testosterone alone is able to facilitate formation of regionally epithelium instead of those for epididymal epithelium (10). This specific structures such as the epididymis, vas deferens, and sem- inductive ability of Wolffian duct mesenchyme was also found in the inal vesicle from a straight Wolffian duct. In this study, we iden- prostate, providing further support that AR in the mesenchyme is tified inhibin beta A (or Inhba) as a regional paracrine factor in necessary to dictate androgenic actions of the epithelium (11). mouse mesonephroi that controls coiling of the epithelium in the Furthermore, when the epithelium from the AR-deficient testicular anterior Wolffian duct, the future epididymis. -
The Zebrafish Presomitic Mesoderm Elongates Through Compression-Extension
bioRxiv preprint doi: https://doi.org/10.1101/2021.03.11.434927; this version posted March 11, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. The zebrafish presomitic mesoderm elongates through compression-extension Lewis Thomson1, Leila Muresan2 and Benjamin Steventon1* 1) Department of Genetics, University of Cambridge, Cambridge, UK, CB2 3EH 2) Cambridge Advanced Imaging Centre, University of Cambridge, Cambridge, UK *[email protected] Abstract In vertebrate embryos the presomitic mesoderm become progressively segmented into somites at the anterior end while extending along the anterior- posterior axis. A commonly adopted model to explain how this tissue elongates is that of posterior growth, driven in part by the addition of new cells from uncommitted progenitor populations in the tailbud. However, in zebrafish, much of somitogenesis is associated with an absence of overall volume increase and posterior progenitors do not contribute new cells until the final stages of somitogenesis. Here, we perform a comprehensive 3D morphometric analysis of the paraxial mesoderm and reveal that extension is linked to a volumetric decrease, compression in both dorsal-ventral and medio-lateral axes, and an increase in cell density. We also find that individual cells decrease in their cell volume over successive somite stages. Live cell tracking confirms that much of this tissue deformation occurs within the presomitic mesoderm progenitor zone and is associated with non-directional rearrangement. Furthermore, unlike the trunk somites that are laid down during gastrulation, tail somites develop from a tissue that can continue to elongate in the absence of functional PCP signalling. -
From Bipotent Neuromesodermal Progenitors to Neural-Mesodermal Interactions During Embryonic Development
International Journal of Molecular Sciences Review From Bipotent Neuromesodermal Progenitors to Neural-Mesodermal Interactions during Embryonic Development Nitza Kahane and Chaya Kalcheim * Department of Medical Neurobiology, Institute of Medical Research Israel-Canada (IMRIC) and the Edmond and Lily Safra Center for Brain Sciences (ELSC), Hebrew University of Jerusalem-Hadassah Medical School, P.O. Box 12272, Jerusalem 9112102, Israel; [email protected] * Correspondence: [email protected] Abstract: To ensure the formation of a properly patterned embryo, multiple processes must operate harmoniously at sequential phases of development. This is implemented by mutual interactions between cells and tissues that together regulate the segregation and specification of cells, their growth and morphogenesis. The formation of the spinal cord and paraxial mesoderm derivatives exquisitely illustrate these processes. Following early gastrulation, while the vertebrate body elongates, a pop- ulation of bipotent neuromesodermal progenitors resident in the posterior region of the embryo generate both neural and mesodermal lineages. At later stages, the somitic mesoderm regulates aspects of neural patterning and differentiation of both central and peripheral neural progenitors. Reciprocally, neural precursors influence the paraxial mesoderm to regulate somite-derived myogen- esis and additional processes by distinct mechanisms. Central to this crosstalk is the activity of the axial notochord, which, via sonic hedgehog signaling, plays pivotal roles in neural, skeletal muscle and cartilage ontogeny. Here, we discuss the cellular and molecular basis underlying this complex Citation: Kahane, N.; Kalcheim, C. developmental plan, with a focus on the logic of sonic hedgehog activities in the coordination of the From Bipotent Neuromesodermal Progenitors to Neural-Mesodermal neural-mesodermal axis. -
The Genetic Basis of Mammalian Neurulation
REVIEWS THE GENETIC BASIS OF MAMMALIAN NEURULATION Andrew J. Copp*, Nicholas D. E. Greene* and Jennifer N. Murdoch‡ More than 80 mutant mouse genes disrupt neurulation and allow an in-depth analysis of the underlying developmental mechanisms. Although many of the genetic mutants have been studied in only rudimentary detail, several molecular pathways can already be identified as crucial for normal neurulation. These include the planar cell-polarity pathway, which is required for the initiation of neural tube closure, and the sonic hedgehog signalling pathway that regulates neural plate bending. Mutant mice also offer an opportunity to unravel the mechanisms by which folic acid prevents neural tube defects, and to develop new therapies for folate-resistant defects. 6 ECTODERM Neurulation is a fundamental event of embryogenesis distinct locations in the brain and spinal cord .By The outer of the three that culminates in the formation of the neural tube, contrast, the mechanisms that underlie the forma- embryonic (germ) layers that which is the precursor of the brain and spinal cord. A tion, elevation and fusion of the neural folds have gives rise to the entire central region of specialized dorsal ECTODERM, the neural plate, remained elusive. nervous system, plus other organs and embryonic develops bilateral neural folds at its junction with sur- An opportunity has now arisen for an incisive analy- structures. face (non-neural) ectoderm. These folds elevate, come sis of neurulation mechanisms using the growing battery into contact (appose) in the midline and fuse to create of genetically targeted and other mutant mouse strains NEURAL CREST the neural tube, which, thereafter, becomes covered by in which NTDs form part of the mutant phenotype7.At A migratory cell population that future epidermal ectoderm. -
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 -
Secreted Molecules in Metanephric Induction
J Am Soc Nephrol 11: S116–S119, 2000 Secreted Molecules in Metanephric Induction THOMAS J. CARROLL and ANDREW P. McMAHON Department of Molecular and Cellular Biology, Biological Laboratories, Harvard University, Cambridge, Massachusetts. Abstract. Nearly 50 yr ago, Clifford Grobstein made the ob- the classic model of metanephric induction. The studies of the servation that the ureteric bud induced the nephrogenic mes- classic ureteric inducer performed to date have most likely enchyme to undergo tubulogenesis. Since that discovery, sci- been characterizations of a mesenchyme-specific inducer, entists have attempted to characterize the molecular nature of Wnt-4, and its role in tubulogenesis. Ureteric induction most the inducer. To date, no single molecule that is both necessary likely involves a series of distinct events that provide prolif- and sufficient for nephric induction has been identified. Be- erative, survival, and condensation signals to the mesenchyme, cause of recent insights regarding the role of several secreted integrating the growth of the ureteric system with tubulogen- molecules in tubulogenesis, it has become necessary to revise esis. The developmental biologic processes of the kidney have been logenesis. The conclusion drawn from this discovery was that the subject of intense study for more than 100 yr (for review, the ureteric bud induces tubulogenesis within the surrounding see reference (1). All three vertebrate kidney types (pro- mesenchyme. During further investigation, it was discovered nephros, mesonephros, and metanephros) are derivatives of a that a number of tissues, including, most notably, a dorsal region of the embryo known as the intermediate mesoderm. In portion of the embryonic spinal cord, are able to substitute for mice, a portion of the mesonephric duct, known as the meta- the ureter in this inductive interaction. -
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. -
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. -
Understanding Paraxial Mesoderm Development and Sclerotome Specification for Skeletal Repair Shoichiro Tani 1,2, Ung-Il Chung2,3, Shinsuke Ohba4 and Hironori Hojo2,3
Tani et al. Experimental & Molecular Medicine (2020) 52:1166–1177 https://doi.org/10.1038/s12276-020-0482-1 Experimental & Molecular Medicine REVIEW ARTICLE Open Access Understanding paraxial mesoderm development and sclerotome specification for skeletal repair Shoichiro Tani 1,2, Ung-il Chung2,3, Shinsuke Ohba4 and Hironori Hojo2,3 Abstract Pluripotent stem cells (PSCs) are attractive regenerative therapy tools for skeletal tissues. However, a deep understanding of skeletal development is required in order to model this development with PSCs, and for the application of PSCs in clinical settings. Skeletal tissues originate from three types of cell populations: the paraxial mesoderm, lateral plate mesoderm, and neural crest. The paraxial mesoderm gives rise to the sclerotome mainly through somitogenesis. In this process, key developmental processes, including initiation of the segmentation clock, formation of the determination front, and the mesenchymal–epithelial transition, are sequentially coordinated. The sclerotome further forms vertebral columns and contributes to various other tissues, such as tendons, vessels (including the dorsal aorta), and even meninges. To understand the molecular mechanisms underlying these developmental processes, extensive studies have been conducted. These studies have demonstrated that a gradient of activities involving multiple signaling pathways specify the embryonic axis and induce cell-type-specific master transcription factors in a spatiotemporal manner. Moreover, applying the knowledge of mesoderm development, researchers have attempted to recapitulate the in vivo development processes in in vitro settings, using mouse and human PSCs. In this review, we summarize the state-of-the-art understanding of mesoderm development and in vitro modeling of mesoderm development using PSCs. We also discuss future perspectives on the use of PSCs to generate skeletal tissues for basic research and clinical applications. -
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.