Lecture 1
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Questions and Answers

What is the primary source of maternal factors in embryonic development?

  • Zygotic genes
  • Cytoplasmic granules
  • Mitochondrial cloud
  • Maternal genes (correct)

    • What is the characteristic of the vegetal pole in oocytes?

  • Less maternal factors
  • Less mitochondria
  • More yolk (correct)
  • More proteins

    • What is the function of cytoplasmic granules in embryonic development?

  • To store zygotic genes
  • To translate maternal mRNAs
  • To synthesize proteins
  • To regulate post-transcriptional processing (correct)

    • When are maternal mRNAs activated during embryonic development?

    <p>After fertilization</p> Signup and view all the answers

    What is the primary characteristic of totipotent cells?

    <p>Ability to differentiate into any cell type in the body</p> Signup and view all the answers

    What is the characteristic of preformed guidelines in embryonic development?

    <p>They are present right at the start of ontogeny</p> Signup and view all the answers

    What is the function of Balbiani body in embryonic development?

    <p>To accumulate mitochondria and cytoplasmic granules</p> Signup and view all the answers

    What is the main difference between pluripotent and multipotent cells?

    <p>Pluripotent cells can differentiate into any cell type, while multipotent cells are limited to a specific lineage</p> Signup and view all the answers

    What is the process of gradual commitment to a specific cell fate called?

    <p>Determination</p> Signup and view all the answers

    What is the difference between the animal and vegetal poles in oocytes?

    <p>The animal pole has more proteins, while the vegetal pole has more maternal factors</p> Signup and view all the answers

    What is the purpose of the color-coding of maternal factors in embryonic development?

    <p>To visualize the expression of proteins</p> Signup and view all the answers

    What is the term for the ability of a cell to respond to an inductive signal?

    <p>Competence</p> Signup and view all the answers

    What type of development is characterized by the potential of a cell being much greater than its normal fate?

    <p>Regulative development</p> Signup and view all the answers

    What is the term for the programmed cell death that regulates proper structure sculpting?

    <p>Apoptosis</p> Signup and view all the answers

    What is the term for the organization of cells in a specific pattern to form a structure?

    <p>Morphogenesis</p> Signup and view all the answers

    What is the term for the ability of a cell to induce a specific response in a neighboring cell?

    <p>Evocative influence</p> Signup and view all the answers

    What is the term for the formation of the dorsal lip of blastopore during embryonic development?

    <p>Primary induction</p> Signup and view all the answers

    What is the term for the presence of normal homeobox genes?

    <p>Positional information</p> Signup and view all the answers

    What mechanism is responsible for eliminating cells between the digits in the development of interdigital webbings?

    <p>Programmed cell death</p> Signup and view all the answers

    What is the function of imaginal discs in insect development?

    <p>To give rise to novel structures</p> Signup and view all the answers

    What is the purpose of PCD in eliminating autoreactive lymphocytes?

    <p>To eliminate abnormal cells</p> Signup and view all the answers

    What is the role of survival-promoting factors in PNS development?

    <p>To promote neuronal survival</p> Signup and view all the answers

    What is the function of the biological clock in somite development?

    <p>To generate somites sequentially</p> Signup and view all the answers

    What is the central mechanism for the generation of oscillatory gene expression in somite development?

    <p>Notch signaling</p> Signup and view all the answers

    What is the function of cell-intrinsic timers in development?

    <p>To change precursor cells over time</p> Signup and view all the answers

    What is the purpose of apoptosis in PNS development?

    <p>To adjust the number of neurons to match their targets</p> Signup and view all the answers

    Which field of study involves biochemical investigations of the embryo and has contributed to the development of molecular biology?

    <p>Chemical Embryology</p> Signup and view all the answers

    What is the primary focus of Experimental Embryology?

    <p>Investigating when and how a process is carried out</p> Signup and view all the answers

    Which area of study is concerned with the abnormal development of embryos, resulting in birth defects?

    <p>Teratology</p> Signup and view all the answers

    What is the broad approach that encompasses embryonic development, normal growth, metamorphosis, regeneration, and tissue repair?

    <p>Developmental Biology</p> Signup and view all the answers

    Which area of study deals with the techniques of fertilization, implantation of embryos, endocrinology of reproduction, and embryonic development?

    <p>Reproductive Embryology</p> Signup and view all the answers

    What is the primary function of the Balbiani Body during oogenesis?

    <p>To transport and localize maternal factors to the vegetal cortex</p> Signup and view all the answers

    What is the significance of the vegetal pole in the egg?

    <p>It has the highest concentration of yolk</p> Signup and view all the answers

    What is the role of microtubule-mediated transport in the establishment of the dorsal axis?

    <p>It translocates Sybu and Wnt8 to the future dorsal axis</p> Signup and view all the answers

    What is the characteristic of the guidelines that appear during ontogeny?

    <p>They come in the form of newly synthesized proteins and signaling factors</p> Signup and view all the answers

    What is the relationship between the anterior-posterior axis and gastrulation?

    <p>The anterior-posterior axis is established during gastrulation</p> Signup and view all the answers

    What is the significance of the dorsal lip of the blastopore (DLB) in embryonic development?

    <p>It has inducing properties that guide the formation of the anterior-posterior axis</p> Signup and view all the answers

    What is the role of Wnt signal activity in the establishment of the anterior-posterior axis?

    <p>It is low in the anterior and high in the posterior</p> Signup and view all the answers

    What is the significance of cell asymmetries in the formation of different cell lineages in the embryo?

    <p>It leads to the formation of different cell lineages</p> Signup and view all the answers

    What is the role of the Oct4 gene in the formation of the inner cell mass (ICM)?

    <p>It is required for the maturation of the ICM</p> Signup and view all the answers

    What is the characteristic of the cells that express Oct4 at a low level during the blastula stage?

    <p>They divide asymmetrically</p> Signup and view all the answers

    What is the primary function of the effector (TH-thyroid hormone) in the cell-intrinsic timer?

    <p>To stop cell division and initiate differentiation at the appropriate time</p> Signup and view all the answers

    What is the term used to describe the DNA sequence containing about 180-nucleotide sequence in the master developmental control genes?

    <p>Homeobox</p> Signup and view all the answers

    What is the term used to describe the process of specifying cell identity and positioning during embryonic development?

    <p>Craniocaudal morphogenesis</p> Signup and view all the answers

    What is the primary function of DNA methylation and Histone acetylation during embryonic development?

    <p>To affect differential expressions of Pluripotency-associated genes and Developmental genes</p> Signup and view all the answers

    Who is credited with the concept of 'omne vivium ex ovo'?

    <p>William Harvey</p> Signup and view all the answers

    What is the term used to describe the theory that the egg does not contain a preformed embryo, but only the materials of which the embryo is formed?

    <p>Theory of Epigenesis</p> Signup and view all the answers

    Who is credited with being the first person to note the many similarities between the embryos of vertebrates, particularly amniotes?

    <p>Karl Ernst von Baer</p> Signup and view all the answers

    What is the term used to describe the process of a single cell, the zygote, undergoing a series of mitotic divisions to form the morula?

    <p>Cleavage</p> Signup and view all the answers

    What is the term used to describe the process of regulating gene expression through DNA methylation and Histone modifications?

    <p>Gene regulation</p> Signup and view all the answers

    What is the term used to describe the master developmental control genes that regulate aspects of morphogenesis and cell differentiation?

    <p>Homeobox genes</p> Signup and view all the answers

    What is the main concept of Von Baer's Law?

    <p>Embryos of different species develop similar structures during early stages</p> Signup and view all the answers

    Who is credited with the concept of 'Ontogeny Recapitulates Phylogeny'?

    <p>Ernst Haeckel</p> Signup and view all the answers

    What is the name of the theory that states that the development of an organism is a shortened and modified version of the evolutionary history of its ancestors?

    <p>Law of Biogenesis</p> Signup and view all the answers

    Who is known for identifying the primary germ layers: endoderm, ectoderm, and mesoderm?

    <p>Christian Pander</p> Signup and view all the answers

    What is the term for the process by which the fertilized egg is divided into future parts of a developing organism?

    <p>Mitotic cell division</p> Signup and view all the answers

    Who is credited with the discovery of the importance of chromosomes in heredity?

    <p>Oscar Hertwig</p> Signup and view all the answers

    What is the term for the phenomenon where the development of an organism is influenced by the presence of certain structures or molecules?

    <p>Embryonic induction</p> Signup and view all the answers

    What is the name of the technique developed in 1990 for the treatment of extreme infertility?

    <p>ICSI</p> Signup and view all the answers

    What is the name of the research approach that involves the detailed study of the structure and arrangement of minute internal organs during embryonic development?

    <p>Descriptive Embryology</p> Signup and view all the answers

    Who is credited with the development of experimental embryology?

    <p>Wilhelm Roux</p> Signup and view all the answers

    What is the mechanism responsible for eliminating cells between the digits in the development of interdigital webbings?

    <p>Programmed cell death mechanism</p> Signup and view all the answers

    What is the primary function of imaginal discs in insect development?

    <p>To provide a cellular template for the formation of adult structures</p> Signup and view all the answers

    What is the role of survival-promoting factors in PNS development?

    <p>To promote the survival of neurons through competition for limited amounts of survival factors</p> Signup and view all the answers

    What is the central mechanism for the generation of oscillatory gene expression in somite development?

    <p>Notch signaling via a transcription factor Hes7</p> Signup and view all the answers

    What is the function of cell-intrinsic timers in development?

    <p>To change precursor cells over time</p> Signup and view all the answers

    What is the purpose of PCD in eliminating autoreactive lymphocytes?

    <p>To eliminate abnormal cells</p> Signup and view all the answers

    What is the term for the formation of the dorsal lip of blastopore during embryonic development?

    <p>Gastrulation</p> Signup and view all the answers

    What is the role of apoptosis in PNS development?

    <p>To match the number of neurons with the number of target cells</p> Signup and view all the answers

    What is the primary function of the Balbiani Body during oogenesis?

    <p>To localize maternal factors to the vegetal cortex during oogenesis</p> Signup and view all the answers

    What is the characteristic of the guidelines that appear during ontogeny?

    <p>They appear gradually in every step of ontogeny</p> Signup and view all the answers

    What is the significance of the dorsal lip of the blastopore (DLB) in embryonic development?

    <p>It has inducing properties that guide the development of posterior neural structures</p> Signup and view all the answers

    What is the role of Wnt signal activity in the establishment of the anterior-posterior axis?

    <p>It is low in the anterior and high in the posterior</p> Signup and view all the answers

    What is the significance of cell asymmetries in the formation of different cell lineages in the embryo?

    <p>It influences the formation of different cell lineages</p> Signup and view all the answers

    What is the characteristic of the cells that express Oct4 at a low level during the blastula stage?

    <p>They divide asymmetrically and give rise to the inner cell mass</p> Signup and view all the answers

    What is the primary function of the microtubule network during oogenesis?

    <p>To mediate the transport of maternal factors to the vegetal cortex</p> Signup and view all the answers

    What is the characteristic of the egg cytoarchitecture?

    <p>It is the study of the cellular structure of the egg</p> Signup and view all the answers

    What is the significance of the vegetal pole in the egg?

    <p>It has a high concentration of yolk</p> Signup and view all the answers

    What is the primary mechanism of progressive formation of guidelines during ontogeny?

    <p>The expression of signaling factors and morphogens</p> Signup and view all the answers

    What is the primary function of p27/Kip1 in the cell-intrinsic timer?

    <p>To accumulate in precursor cells as they proliferate</p> Signup and view all the answers

    What is the characteristic of homeobox genes in invertebrates and vertebrates?

    <p>They are conserved and correlated with the position of Hox genes in the cluster</p> Signup and view all the answers

    What is the primary mechanism of differential gene expression during embryonic development?

    <p>DNA methylation and Histone acetylation</p> Signup and view all the answers

    Who is credited with being the first person to do a systematic study of embryos?

    <p>Aristotle</p> Signup and view all the answers

    What is the primary function of the effector (TH-thyroid hormone) in the cell-intrinsic timer?

    <p>To stop cell division and initiate differentiation</p> Signup and view all the answers

    What is the term used to describe the process of specifying cell identity and positioning during embryonic development?

    <p>Craniocaudal morphogenesis</p> Signup and view all the answers

    What is the role of Hox genes in normal development?

    <p>Patterning embryonic structures</p> Signup and view all the answers

    What is the term used to describe the theory that the egg contains a preformed embryo?

    <p>Theory of Preformation</p> Signup and view all the answers

    What is the primary function of oligodendrocytes?

    <p>Forming the myelin sheath of nerve cells outside the CNS</p> Signup and view all the answers

    Who is credited with being the 'Father of Embryology'?

    <p>Karl Ernst von Baer</p> Signup and view all the answers

    What is the primary characteristic of preformed guidelines in embryonic development?

    <p>are present right at the start of ontogeny, even before fertilization</p> Signup and view all the answers

    What is the role of the Balbiani body in amphibian and fish oocytes?

    <p>accumulation of mitochondria and cytoplasmic granules containing silenced mRNAs</p> Signup and view all the answers

    What is the term for the genes that result from the fusion of maternal and paternal genes during fertilization?

    <p>Zygotic genes</p> Signup and view all the answers

    What is the characteristic of the vegetal pole in oocytes?

    <p>has more yolk</p> Signup and view all the answers

    What is the process by which maternal mRNAs are activated during embryonic development?

    <p>fertilization</p> Signup and view all the answers

    What is the term for the maternal factors that are present in the oocyte before fertilization?

    <p>Maternal genes</p> Signup and view all the answers

    What is the characteristic of the animal pole in oocytes?

    <p>has more proteins</p> Signup and view all the answers

    What is the role of cytoplasmic granules in embryonic development?

    <p>organization of maternal mRNAs and regulatory proteins</p> Signup and view all the answers

    What is the primary characteristic of totipotent cells in embryonic development?

    <p>Ability to give rise to any cell type in the entire organism</p> Signup and view all the answers

    What is the key difference between pluripotent and multipotent cells?

    <p>Pluripotent cells can differentiate into any cell type, while multipotent cells can only differentiate into cell types within a given lineage</p> Signup and view all the answers

    What is the process of gradual commitment to a specific cell fate called?

    <p>Determination</p> Signup and view all the answers

    What is the term for the ability of a cell to respond to an inductive signal?

    <p>Competence</p> Signup and view all the answers

    What type of development is characterized by the potential of a cell being much greater than its normal fate?

    <p>Regulative development</p> Signup and view all the answers

    What is the term for the programmed cell death that regulates proper structure sculpting?

    <p>Apoptosis</p> Signup and view all the answers

    What is the primary function of programmed cell death during embryonic development?

    <p>To eliminate excess cells during morphogenesis</p> Signup and view all the answers

    What is the term for the organization of cells in a specific pattern to form a structure?

    <p>Morphogenesis</p> Signup and view all the answers

    What is the term for the ability of a cell to induce a specific response in a neighboring cell?

    <p>Evocative influence</p> Signup and view all the answers

    What is the primary characteristic of the chordamesoderm (CM) during embryonic development?

    <p>It has the ability to induce the formation of the neural plate</p> Signup and view all the answers

    What is the fundamental concept of Ernst Haeckel's theory of 'Ontogeny recapitulates Phylogeny'?

    <p>Individual development progresses through the adult stages of the organism's ancestors</p> Signup and view all the answers

    Who is credited with the discovery of the primary germ layers: endoderm, ectoderm, and mesoderm?

    <p>Christian Pander</p> Signup and view all the answers

    What is the fundamental concept of Von Baer's Law?

    <p>Uninterrupted series of correlated events occur during embryonic development</p> Signup and view all the answers

    Who is credited with founding the field of experimental embryology?

    <p>Wilhelm Roux</p> Signup and view all the answers

    What is the term for the theory that the germ cells are not influenced by the body that bears them?

    <p>The Germplasm Theory</p> Signup and view all the answers

    What is the term for the process of fertilization in which the sperm is directly injected into the oocyte cytoplasm?

    <p>Intracytoplasmic Sperm Injection (ICSI)</p> Signup and view all the answers

    Who is credited with the concept of Embryonic Induction?

    <p>Hans Spemann and Hilde Mangold</p> Signup and view all the answers

    What is the term for the process of embryonic development in which the organism passes through a series of constructive stages like those of its ancestors?

    <p>Ontogeny recapitulates Phylogeny</p> Signup and view all the answers

    Who is credited with laying the foundation of Modern Embryology and Histology?

    <p>Matthias Schleiden and Theodor Schwann</p> Signup and view all the answers

    What is the term for the theory that all animal tissues are composed of cells?

    <p>The Cell Theory</p> Signup and view all the answers

    What is the mechanism responsible for deleting cells between the digits in the development of interdigital webbings?

    <p>Programmed cell death</p> Signup and view all the answers

    What is the function of imaginal discs in insect development?

    <p>To generate novel structures from undifferentiated cells</p> Signup and view all the answers

    What is the purpose of PCD in eliminating autoreactive lymphocytes?

    <p>To remove abnormal cells</p> Signup and view all the answers

    What is the role of survival-promoting factors in PNS development?

    <p>To provide a competitive advantage for neuron survival</p> Signup and view all the answers

    What is the function of the biological clock in somite development?

    <p>To generate oscillatory gene expression</p> Signup and view all the answers

    What is the central mechanism for the generation of oscillatory gene expression in somite development?

    <p>Notch signaling</p> Signup and view all the answers

    What is the function of cell-intrinsic timers in development?

    <p>To change precursor cells over time</p> Signup and view all the answers

    What is the purpose of apoptosis in PNS development?

    <p>To match the number of neurons with their targets</p> Signup and view all the answers

    What is the primary difference between preformed and progressively formed guidelines in embryonic development?

    <p>Preformed guidelines are expressed during oogenesis, while progressively formed guidelines are expressed during ontogeny.</p> Signup and view all the answers

    What is the role of Balbiani body in oogenesis?

    <p>It organizes maternal mRNAs in cytoplasmic granules.</p> Signup and view all the answers

    What is the characteristic of the vegetal pole in oocytes?

    <p>It contains more maternal factors and fewer proteins.</p> Signup and view all the answers

    What is the significance of maternal factors in embryonic development?

    <p>They are organized in cytoplasmic granules and silenced until fertilization.</p> Signup and view all the answers

    What is the relationship between maternal genes and maternal effect genes?

    <p>Maternal genes regulate zygotic gene expression, while maternal effect genes regulate oogenesis.</p> Signup and view all the answers

    What is the significance of cytoplasmic granules in oogenesis?

    <p>They organize maternal mRNAs and regulate their translation.</p> Signup and view all the answers

    What is the characteristic of progressively formed guidelines in embryonic development?

    <p>They appear gradually during ontogeny as a result of zygotic gene expression.</p> Signup and view all the answers

    What is the significance of fertilization in the activation of maternal mRNAs?

    <p>It activates maternal mRNAs and regulates their translation.</p> Signup and view all the answers

    What is the primary characteristic of totipotent cells compared to pluripotent cells?

    <p>They can differentiate into any cell type, including extraembryonic membranes.</p> Signup and view all the answers

    What is the main difference between regulative and mosaic development?

    <p>Regulative development has unlimited potential, while mosaic development has limited potential.</p> Signup and view all the answers

    What is the role of the chordamesoderm (CM) in embryonic induction?

    <p>It induces the formation of the neural plate.</p> Signup and view all the answers

    What is the primary function of programmed cell death (PCD) during development?

    <p>To eliminate interdigital webbings during limb development.</p> Signup and view all the answers

    What is the term for the ability of a cell to respond to an inductive signal?

    <p>Competence</p> Signup and view all the answers

    What is the primary characteristic of multipotent cells compared to pluripotent cells?

    <p>They can differentiate into multiple cell types within a specific lineage.</p> Signup and view all the answers

    What is the term for the gradual commitment to a specific cell fate?

    <p>Determination</p> Signup and view all the answers

    What is the primary function of the dorsal lip of the blastopore during embryonic development?

    <p>To organize the formation of the germ layers.</p> Signup and view all the answers

    What is the term for the process of cell-cell interactions that influence development?

    <p>Induction</p> Signup and view all the answers

    What is the primary characteristic of unipotent cells compared to multipotent cells?

    <p>They can only differentiate into a single specific cell type.</p> Signup and view all the answers

    What is the primary component of the cell-intrinsic timer that measures elapsed time?

    <p>PDGF-platelet-derived growth factor</p> Signup and view all the answers

    What is the primary function of homeobox genes?

    <p>To regulate gene expression during embryonic development</p> Signup and view all the answers

    What is the term used to describe the process of specifying cell identity and positioning during embryonic development?

    <p>Craniocaudal morphogenesis</p> Signup and view all the answers

    What is the primary mechanism of differential gene expression during embryonic development?

    <p>DNA methylation and Histone acetylation</p> Signup and view all the answers

    Who is credited with the concept of 'omne vivium ex ovo'?

    <p>William Harvey</p> Signup and view all the answers

    What is the term used to describe the theory that the egg contains a preformed embryo?

    <p>Theory of Preformation</p> Signup and view all the answers

    Who is credited with being the first person to note the many similarities between the embryos of vertebrates, particularly amniotes?

    <p>Karl Ernst von Baer</p> Signup and view all the answers

    What is the primary function of the effector (TH-thyroid hormone) in the cell-intrinsic timer?

    <p>To stop cell division and initiate differentiation</p> Signup and view all the answers

    What is the term used to describe the process of regulating gene expression through DNA methylation and Histone modifications?

    <p>Epigenetic regulation</p> Signup and view all the answers

    What is the primary component of the master developmental control genes?

    <p>Homeodomain</p> Signup and view all the answers

    What is the primary function of Sybu and Wnt6 during embryonic development?

    <p>To influence the establishment of the future dorsal side of the embryo</p> Signup and view all the answers

    What is the characteristic of the guidelines that appear during ontogeny?

    <p>They are gradually formed during embryonic development</p> Signup and view all the answers

    What is the significance of the dorsal lip of the blastopore (DLB) in embryonic development?

    <p>It has inducing properties and synthesizes signaling factors</p> Signup and view all the answers

    What is the role of cell asymmetries in the formation of different cell lineages in the embryo?

    <p>It affects the formation of different cell lineages in the embryo</p> Signup and view all the answers

    What is the primary function of the Oct4 gene in the formation of the inner cell mass (ICM)?

    <p>To regulate the maturation of the inner cell mass</p> Signup and view all the answers

    What is the characteristic of the cells that express Oct4 at a low level during the blastula stage?

    <p>They divide asymmetrically and have small and large cells</p> Signup and view all the answers

    What is the role of Wnt signal activity in the establishment of the anterior-posterior axis?

    <p>It is high in the posterior and low in the anterior</p> Signup and view all the answers

    What is the significance of the vegetal pole in the egg?

    <p>It has the highest concentration of yolk</p> Signup and view all the answers

    What is the primary function of the Balbiani body during oogenesis?

    <p>To transport and localize maternal factors to the vegetal cortex</p> Signup and view all the answers

    What is the relationship between the anterior-posterior axis and gastrulation?

    <p>The anterior-posterior axis is established during gastrulation</p> Signup and view all the answers

    What is the primary concept of Ernst Haeckel's Law of Biogenesis?

    <p>That individual development progresses through the adult stages of the organism's ancestors</p> Signup and view all the answers

    Who is credited with the discovery of the primary germ layers, including endoderm, ectoderm, and mesoderm?

    <p>Christian Pander</p> Signup and view all the answers

    What is the term used to describe the process of shortened or modified recapitulation of phylogeny during individual development?

    <p>Biogenesis</p> Signup and view all the answers

    Who is credited with the development of the concept of embryonic induction?

    <p>Hans Spemann</p> Signup and view all the answers

    What is the term used to describe the process of fertilization of an egg cell outside the human body?

    <p>In-Vitro Fertilization (IVF)</p> Signup and view all the answers

    What is the primary function of the nucleus of a chicken egg?

    <p>To provide genetic material for the development of the embryo</p> Signup and view all the answers

    Who is credited with the development of the Germplasm theory?

    <p>August Weismann</p> Signup and view all the answers

    What is the term used to describe the process of determining the formation of the vertebral column during embryonic development?

    <p>Notocord formation</p> Signup and view all the answers

    Who is credited with the development of experimental embryology?

    <p>Wilhelm Roux</p> Signup and view all the answers

    What is the term used to describe the process of development of an organism from a fertilized egg cell to a mature adult?

    <p>Ontogeny</p> Signup and view all the answers

    Study Notes

    Guidelines on Embryonic Development

    • Preformed Guidelines: present at the start of ontogeny, referring to maternal factors resulting from the activation of maternal genes/maternal effect genes.
    • Progressively-formed Guidelines: appear gradually in every step of ontogeny, referring to cellular products as a result of zygotic genes.

    Maternal Factors

    • Maternal factors are maternal mRNA which are silenced or not expressed as proteins, waiting for their activation.
    • Oocytes (amphibian and fish oocytes) have distinct poles: animal and vegetal.
    • Vegetal pole has more yolk and maternal factors.
    • Maternal factors are color-coded (e.g. VegT mRNA is purple).
    • The unequal distribution of vegetal pole having more maternal factors and the animal pole having more proteins forms preformed guidelines.

    Balbiani Body

    • Located at the vegetal pole, it accumulates mitochondria and cytoplasmic granules (germ granules) containing silenced mRNAs.
    • Mitochondrial cloud + cytoplasmic granules (germ granules) organize maternal mRNAs, which are silent until activated by fertilization.

    Egg Cytoarchitecture

    • Study of the cellular structure of the egg, including its yolk distribution.
    • Vegetal pole has the highest concentration of yolk.
    • All animals have different amounts of yolk, which affects the cleavage pattern of the oocyte.

    Progressively-formed Guidelines

    • At the cleavage stage, the pattern is under maternal control.
    • In the late cleavage stage, maternal factors become depleted, and zygotic genes are activated.
    • New proteins are expressed progressively in the gastrula stage and beyond.
    • Guidelines come in the form of newly synthesized proteins and signaling factors.

    Anterior-Posterior Axis

    • Coupled to gastrulation.
    • Gradually laid down in gastrulation.
    • Guided by developmental potential and inducing properties of cells in the dorsal lip of the blastopore (DLB).

    Dorsal Blastopore Lip

    • Has inducing properties, but cells must have the ability to respond.
    • Synthesizes signaling factors that are expressed at different areas and times.

    Fate

    • "What cells would become."
    • The range of cell types that a particular embryonic cell can give rise to.
    • Dependent on cell asymmetries, unequal cytoplasmic determinants, inductive information, and morphogens.

    Embryonic Induction

    • Evocative influence of cells, within a cell or a cell with a neighboring cell, and between cells.
    • Capacity & Competence: chordamesoderm (CM) has the capacity to induce, and the ectoderm has the competence to respond.

    Regulation

    • Regulative vs. Mosaic Development:
      • Regulative development: potential of a cell is much greater than what is indicated in its normal fate.
      • Mosaic development: embryonic cells can develop only according to their early fate.

    Inevitability

    • Phenomena that will take place and the embryo cannot evade from this.
    • Examples: apoptosis, biological clock, positional information.

    Homeobox Genes

    • Act at the top of genetic hierarchies regulating aspects of morphogenesis and cell differentiation.
    • Encode DNA-binding proteins that regulate gene expression.
    • Regulate gene expression and control aspects of morphogenesis and cell differentiation.

    Differentiation

    • Single cell (zygote) embarks on a series of mitotic divisions forming the cleavage or morula.
    • Morula: solid ball of cells.
    • Differential gene expression: vary in the subset of genes they express.
    • Regulated by mechanisms: DNA methylation, histone modifications, and H3K27 methylation.

    Historical Background

    • Important people in the history of embryology: Aristotle, William Harvey, Graaf, Hamm, Leuwenhoek, Lazzaro Spallanzani, Caspar Friedrich Wolff, and Karl Ernst Von Baer.
    • Theories: Preformation, Epigenesis, and Biogenesis.
    • Von Baer's Law: the more general features that are common to all members of a group of animals developed earlier than the more special features which distinguish the various members of the group.
    • Law of Biogenesis: Ontogeny is a shortened/modified recapitulation of phylogeny.### Germ Layers and Early Embryology
    • Christian Pander identified the primary germ layers: endoderm, ectoderm, and mesoderm
    • He observed the presence of pharyngeal pouches in embryos of higher and lower vertebrates
    • Every species forms gill slits at certain development stages
    • Differences between pharyngeal pouches and clefts: pouches are lined with endoderm, while clefts are lined with ectoderm

    Founders of Modern Embryology and Histology

    • Matthias Schleiden (1838) concluded that all plant parts are made of cells
    • Theodor Schwann (1839) stated that all animal tissues are composed of cells

    Experimental Embryology

    • Wilhelm Roux (1880) began a program to experiment on frog eggs to elucidate mitotic cell division
    • He founded experimental embryology and believed that mitotic cell division determines the development of future organism parts

    Integration of Genetics into Embryonic Development

    • August Weismann's Germplasm theory: self-reproducing determinants guide morphogenesis, and offspring inherit characteristics from germ cells (egg and sperm) rather than the parent's body
    • Chromosomes: Oscar observed sexual reproduction and demonstrated fertilization (sea urchin), existence of polar bodies, and advances in meiosis understanding

    Hans Spemann and Hilde Mangold

    • 1935 Nobel Prize in Medicine for the concept of Embryonic Induction and the organizer effect (dorsal lip of blastopore)

    Model Organisms in Embryology

    • Wilhelm Roux: Frog and Sea Urchin
    • Thomas Hunt Morgan: Fruitfly

    Milestones in Developmental Biology

    • Era of Assisted Reproduction Technology (ART)
    • Edward and Steptoe (1978): In-Vitro Fertilization (IVF) and the first test tube baby, Louise Brown
    • ICSI (Intracytoplasmic Sperm Injection): first ICSI baby born in 1992, used for extreme infertility cases, and involves direct sperm injection into the oocyte cytoplasm

    Approaches in the Study of Embryology

    • Descriptive Embryology: detailed study of structure and arrangement of internal organs
    • Comparative Embryology: establishes relationships between developmental stages
    • Experimental Embryology: finds out why a process is carried out at a specific time in a specific manner
    • Chemical Embryology: involves biochemical investigations of the embryo, ushering in molecular biology
    • Teratology: study of embryonic malformations
    • Reproductive Embryology: techniques in fertilization, implantation of embryos, and endocrinology of reproduction and embryonic development
    • Developmental Biology: broader approach from embryonic development to postnatal development, including normal growth, metamorphosis, regeneration, and tissue repair

    Here are the study notes:

    Directive Influences on Embryonic Development

    • Preformed Guidelines:
      • Present at the start of ontogeny, even before fertilization
      • Refers to maternal factors as a result of maternal genes/ maternal effect genes
      • Maternal factors are silenced or not expressed as proteins, waiting for their activation
    • Progressively-Formed Guidelines:
      • Appear gradually in every step of ontogeny
      • Pertains to cellular products as a result of zygotic genes
      • New proteins are expressed progressively in the gastrula stage and in the next stages

    Maternal Effect Genes/Factors in Amphibian and Fish Oocytes

    • Oocyte Cytoarchitecture:
      • Maternal factors are silenced or not expressed as proteins, waiting for their activation
      • Vegetal pole has more yolk and maternal factors, while animal pole has more proteins
    • Balbiani Body (BB) and Mitochondrial Cloud:
      • Accumulation of mitochondria and cytoplasmic granules (germ granules) containing silenced mRNAs
      • Maternal mRNAs are silent until activated by fertilization; protein expression occurs immediately
    • Sybu and Wnt6:
      • Translocated from the vegetal pole to the future dorsal axis through microtubule-mediated transport
      • Influence the establishment of the future dorsal side of the embryo

    Egg Cytoarchitecture

    • Vegetal Pole:
      • Has the highest concentration of yolk
      • Affects the cleavage pattern of the oocyte
    • Yolk Distribution:
      • Affects the cleavage pattern of the oocyte
      • Different animals have different amounts of yolk

    Progressively-Formed Guidelines

    • Cleavage Stage:
      • Pattern is under maternal control
      • Maternal factors become depleted, and zygotic genes are activated
    • Gastrula Stage:
      • New proteins are expressed progressively
      • Guidelines come in the form of newly synthesized proteins and signaling factors
    • Anterior-Posterior Axis:
      • Is coupled to gastrulation
      • Is guided by developmental potential and inducing properties of cells in the dorsal lip of the blastopore (DLB)

    Cell Fate and Potency

    • Fate:
      • Refers to "what cells would become"
      • Depends on cell asymmetries, unequal cytoplasmic determinants, inductive information, and morphogens
    • Potency:
      • Ability of a cell to follow a developmental pathway
      • Totipotent (blastomeres), pluripotent (inner cell mass), multipotent, and unipotent cells

    Embryonic Induction and Capacity & Competence

    • Evocative Influence:
      • Influence of cells within a cell or between cells
      • Cells have the capacity to induce, and the responding cells have the competence to respond
    • Primary Induction:
      • Formation of the dorsal lip of the blastopore, which has inducing properties
      • Influences the overlying ectoderm to form the precursor cells of the central nervous system

    Regulation and Determination

    • Regulative vs Mosaic Development:
      • Regulative development: cells have unlimited potential, and their fate is determined by inductive signals
      • Mosaic development: cells are determined early and follow a fixed path
    • Determination:
      • Gradual commitment to a certain cell fate
      • Geared to follow a certain developmental pathway

    Programmed Cell Death

    • Functions:
      • Regulates sculpting of structures
      • Eliminates cells that fail to partner with target cells
      • Controls cell number by deleting cells that are abnormal or autoreactive
    • Mechanisms:
      • Involves the activation of specific genes and signaling pathways

    Biological Clock and Homeobox Genes

    • Biological Clock:
      • Refers to the somite segmentation clock
      • Regulates the formation of repeated structures in embryogenesis
    • Homeobox Genes:
      • Act as transcription factors that regulate gene expression
      • Involved in patterning embryonic structures, segmentations, and morphogenesis### Christian Pander
    • Identified the primary germ layers: endoderm, ectoderm, and mesoderm
    • Observed the similarity between embryos of higher and lower vertebrates due to the presence of pharyngeal pouches
    • Every species forms gill slits at certain development stages

    Pouches and Clefts

    • Pouch: side lined with endoderm, outpocketing of the oral/pharyngeal cavity
    • Cleft: side lined with ectoderm

    Schleiden & Schwann (1839)

    • Laid the foundation of Modern Embryology and Histology with the advent of the microscope
    • Matthias Schleiden: concluded that all plant parts are made of cells (1838)
    • Theodor Schwann: stated that all animal tissues are composed of cells (1839)

    Wilhelm Roux

    • Founder of experimental embryology
    • Believed that mitotic cell division of the fertilized egg determines the future parts of a developing organism
    • Experimented on frog eggs to elucidate mitotic cell division (1880)

    Integration of Genetics into Embryonic Development

    • August Weismann's Germplasm theory:
    • Self-reproducing determinants guide morphogenesis
    • Offspring inherit characteristics from germ cells (egg and sperm), not from the parent's body
    • Germ cells are not influenced by the body that bears them
    • Chromosomes: a key component of Weismann's Germplasm theory

    Oscar & Richard Hertwig

    • Oscar: first to observe sexual reproduction, demonstrated fertilization (sea urchin), and observed polar bodies and meiosis
    • Richard Hertwig: contributed to the understanding of meiosis

    Hans Spemann & Hilde Mangold

    • 1935 Nobel Prize for Medicine for the concept of Embryonic Induction
    • Organizer effect: dorsal lip of blastopore

    Model Organisms

    • Wilhelm Roux: Frog and Sea Urchin
    • Thomas Hunt Morgan: Fruitfly

    Milestones in Developmental Biology

    • ERA of ART (Assisted Reproduction Technology)
    • Edward & Steptoe (1978): In-Vitro Fertilization (IVF), first test tube baby - Louise Brown
    • ICSI: intracytoplasmic sperm injection (1990)
    • First ICSI baby born in 1992
    • Technology of choice in cases of extreme infertility
    • Involves introducing sperm directly into the oocyte cytoplasm using a micromanipulator

    Here are the study notes:

    Directive Influences on Embryonic Development

    • Preformed Guidelines:
      • Present at the start of ontogeny, even before fertilization
      • Refers to maternal factors as a result of maternal genes/ maternal effect genes
      • Maternal factors are silenced or not expressed as proteins, waiting for their activation
    • Progressively-Formed Guidelines:
      • Appear gradually in every step of ontogeny
      • Pertains to cellular products as a result of zygotic genes
      • New proteins are expressed progressively in the gastrula stage and in the next stages

    Maternal Effect Genes/Factors in Amphibian and Fish Oocytes

    • Oocyte Cytoarchitecture:
      • Maternal factors are silenced or not expressed as proteins, waiting for their activation
      • Vegetal pole has more yolk and maternal factors, while animal pole has more proteins
    • Balbiani Body (BB) and Mitochondrial Cloud:
      • Accumulation of mitochondria and cytoplasmic granules (germ granules) containing silenced mRNAs
      • Maternal mRNAs are silent until activated by fertilization; protein expression occurs immediately
    • Sybu and Wnt6:
      • Translocated from the vegetal pole to the future dorsal axis through microtubule-mediated transport
      • Influence the establishment of the future dorsal side of the embryo

    Egg Cytoarchitecture

    • Vegetal Pole:
      • Has the highest concentration of yolk
      • Affects the cleavage pattern of the oocyte
    • Yolk Distribution:
      • Affects the cleavage pattern of the oocyte
      • Different animals have different amounts of yolk

    Progressively-Formed Guidelines

    • Cleavage Stage:
      • Pattern is under maternal control
      • Maternal factors become depleted, and zygotic genes are activated
    • Gastrula Stage:
      • New proteins are expressed progressively
      • Guidelines come in the form of newly synthesized proteins and signaling factors
    • Anterior-Posterior Axis:
      • Is coupled to gastrulation
      • Is guided by developmental potential and inducing properties of cells in the dorsal lip of the blastopore (DLB)

    Cell Fate and Potency

    • Fate:
      • Refers to "what cells would become"
      • Depends on cell asymmetries, unequal cytoplasmic determinants, inductive information, and morphogens
    • Potency:
      • Ability of a cell to follow a developmental pathway
      • Totipotent (blastomeres), pluripotent (inner cell mass), multipotent, and unipotent cells

    Embryonic Induction and Capacity & Competence

    • Evocative Influence:
      • Influence of cells within a cell or between cells
      • Cells have the capacity to induce, and the responding cells have the competence to respond
    • Primary Induction:
      • Formation of the dorsal lip of the blastopore, which has inducing properties
      • Influences the overlying ectoderm to form the precursor cells of the central nervous system

    Regulation and Determination

    • Regulative vs Mosaic Development:
      • Regulative development: cells have unlimited potential, and their fate is determined by inductive signals
      • Mosaic development: cells are determined early and follow a fixed path
    • Determination:
      • Gradual commitment to a certain cell fate
      • Geared to follow a certain developmental pathway

    Programmed Cell Death

    • Functions:
      • Regulates sculpting of structures
      • Eliminates cells that fail to partner with target cells
      • Controls cell number by deleting cells that are abnormal or autoreactive
    • Mechanisms:
      • Involves the activation of specific genes and signaling pathways

    Biological Clock and Homeobox Genes

    • Biological Clock:
      • Refers to the somite segmentation clock
      • Regulates the formation of repeated structures in embryogenesis
    • Homeobox Genes:
      • Act as transcription factors that regulate gene expression
      • Involved in patterning embryonic structures, segmentations, and morphogenesis### Christian Pander
    • Identified the primary germ layers: endoderm, ectoderm, and mesoderm
    • Observed the similarity between embryos of higher and lower vertebrates due to the presence of pharyngeal pouches
    • Every species forms gill slits at certain development stages

    Pouches and Clefts

    • Pouch: side lined with endoderm, outpocketing of the oral/pharyngeal cavity
    • Cleft: side lined with ectoderm

    Schleiden & Schwann (1839)

    • Laid the foundation of Modern Embryology and Histology with the advent of the microscope
    • Matthias Schleiden: concluded that all plant parts are made of cells (1838)
    • Theodor Schwann: stated that all animal tissues are composed of cells (1839)

    Wilhelm Roux

    • Founder of experimental embryology
    • Believed that mitotic cell division of the fertilized egg determines the future parts of a developing organism
    • Experimented on frog eggs to elucidate mitotic cell division (1880)

    Integration of Genetics into Embryonic Development

    • August Weismann's Germplasm theory:
    • Self-reproducing determinants guide morphogenesis
    • Offspring inherit characteristics from germ cells (egg and sperm), not from the parent's body
    • Germ cells are not influenced by the body that bears them
    • Chromosomes: a key component of Weismann's Germplasm theory

    Oscar & Richard Hertwig

    • Oscar: first to observe sexual reproduction, demonstrated fertilization (sea urchin), and observed polar bodies and meiosis
    • Richard Hertwig: contributed to the understanding of meiosis

    Hans Spemann & Hilde Mangold

    • 1935 Nobel Prize for Medicine for the concept of Embryonic Induction
    • Organizer effect: dorsal lip of blastopore

    Model Organisms

    • Wilhelm Roux: Frog and Sea Urchin
    • Thomas Hunt Morgan: Fruitfly

    Milestones in Developmental Biology

    • ERA of ART (Assisted Reproduction Technology)
    • Edward & Steptoe (1978): In-Vitro Fertilization (IVF), first test tube baby - Louise Brown
    • ICSI: intracytoplasmic sperm injection (1990)
    • First ICSI baby born in 1992
    • Technology of choice in cases of extreme infertility
    • Involves introducing sperm directly into the oocyte cytoplasm using a micromanipulator

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    This quiz covers the directive influences on embryonic development, including preformed and progressively-formed guidelines. It explores the role of maternal and zygotic genes in shaping development.

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