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Comprehending Development: Generating New Cells and Organs

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1 Comprehending Development: Generating New Cells and Organs
BIOL 370 – Developmental Biology Topic #1 Comprehending Development: Generating New Cells and Organs Lange

2 The focus in BIOL 370 – Developmental Biology is to understand the physiological principles that guide development in multicellular organisms. This course will pull information from a wide array of approaches to study biology including…. physiology, genetics, anatomy, and cellular biology. V.M. - Amphibian Life Cycle

3 Developmental history of the leopard frog, Rana pipiens
DevBio9e-Fig jpg Embryogenesis – the stages of the life cycle from fertilization through hatching (or parturition in mammals). Gametogenesis – the period of time(s) where germ cell lines are in production in some form (Note that in the above, the purple color is showing times of strong germ cell development, whereas the beige is showing times of strong somatic cell development.)

4 Heinz Christian Pander
Russian biologist, has been credited for the discovery of the three germ layers that form during embryogenesis. Pander received his doctorate in zoology from the University of Wurzburg in 1817. He began his studies in embryology using chicken eggs, which allowed for his discovery of the ectoderm, mesoderm and endoderm. Due to his findings, Pander is sometimes referred to as the "founder of embryology".

5 Early development of the frog Xenopus laevis
Amplexus – the mating behavioral displayed by frogs where the male will grasp the female around the belly and deposit sperm onto eggs as they are released. Notes: Yolk is in green Adults mating Laid eggs d – i) Development beyond the fertilized egg DevBio9e-Fig jpg

6 Continued development of Xenopus laevis
Continued development showing a variety of stages. Note: i) – mature tadpole that has hatched from the egg DevBio9e-Fig jpg

7 Metamorphosis of the frog
Metamorphosis - biological process by which an animal physically develops after birth or hatching that involves a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Various insects, amphibians, molluscs, crustaceans, Cnidarians, echinoderms and tunicates may undergo metamorphosis. Most examples of metamorphosis are also accompanied by a change in habitat and/or behavior. DevBio9e-Fig jpg

8 Summary of meiosis In your review of meiosis, be sure to note the following: Homologus chromosomes - chromosome pairs of the same length, centromere position, and staining pattern, with genes for the same characteristics at corresponding loci. One homologous chromosome is inherited from the organism's mother; the other from the organism's father. They are not identical, but carry the same type of information. Homologus chromatids - sister chromatids are generated when a single chromosome is replicated into two copies of itself, these copies being called sister chromatids. DevBio9e-Fig (1).jpg

9 Summary of meiosis The resulting production of gametes is the method by which sexually reproducing species produce haploid cells that can be mixed together to create offspring with greater genetic diversity than is seen in asexual reproduction. DevBio9e-Fig (2).jpg

10 Depictions of chick developmental anatomy
When we examine chick development, we can see a variety of interesting anatomical aspects. DevBio9e-Fig jpg

11 Depictions of chick developmental anatomy (Part 1)
DevBio9e-Fig R.jpg Classic Drawing by Malpighi (1672)

12 Depictions of chick developmental anatomy (Part 2)
DevBio9e-Fig R.jpg Lillie, 1908

13 Depictions of chick developmental anatomy (Part 3)
DevBio9e-Fig R.jpg Eduard d’Alton

14 Depictions of chick developmental anatomy (Part 4)
DevBio9e-Fig R.jpg

15 Dividing cells of the fertilized egg form three embryonic germ layers
As development progresses beyond the zygote and blastula, you see greater differentiation in the gastrula stage. DevBio9e-Fig jpg

16 Dividing cells of the fertilized egg form three embryonic germ layers (Part 1)
Ectoderm: Differentiates to form the nervous system (spine, peripheral nerves and brain), tooth enamel and the epidermis. It also forms the lining of mouth, anus, nostrils, sweat glands, hair and nails. DevBio9e-Fig R.jpg

17 Dividing cells of the fertilized egg form three embryonic germ layers (Part 2)
Mesoderm: Forms mesenchyme (connective tissue), mesothelium, blood cells and coelomocytes (immune cells in worms and spiders) Mesothelium lines coeloms; forms the muscles in a process known as myogenesis. DevBio9e-Fig R.jpg

18 Dividing cells of the fertilized egg form three embryonic germ layers (Part 3)
Endoderm: Parts of the alimentary canal), the lining cells of all the glands which open into the digestive tube, general respiratory tract, the trachea, bronchi, and alveoli, general endocrine glands and organs, parts of the auditory system (the epithelium of the auditory tube and tympanic cavity), urinary system (the urinary bladder and part of the urethra). DevBio9e-Fig R.jpg

19 The notochord is an interesting structure that is seen only during embryological development. In early development, it defines the primitive axis of the embryo. In some chordates, it persists throughout life as the main axial support of the body, while in most vertebrates it becomes the nucleus pulposus of the intervertebral disc.

20 This image is showing a computer enhanced image of the vertebrate head (in this case a salamander) early in development. The purple colored regions indicate what are called: Pharyngeal Arches (Branchial Arches). In the next slide, look at how these structures develop into various parts of the skeletal bones of the head in different vertebrates.

21 Evolution of pharyngeal arch structures in the vertebrate head
DevBio9e-Fig jpg

22 Notochord in chick development
Notochord - guides development of of the nervous system (neural tube/groove) Somites – vertebrae, ribs, skeletal muscle. DevBio9e-Fig jpg Above – chick To the right - frog

23 Similarities and differences among vertebrate embryos during development
DevBio9e-Fig jpg

24 Fate Maps and Cell Lineages:
Unlike in adults, the cells in the embryo tend to move and shift. Therefore, in developmental biology it is cruicial to identify the following two types of cells: Epithelial cells – cells that are very tightly connected to each other and form sheets of tissue or tubes of tissue. Mesenchymal cells – cells that ARE NOT connected to each other and function as independent units. Fate map for Drosophila sp. eggs.

25 Direction and number of cell divisions
Morphogenesis – a limited range of variations in processes of a cell within epithelial and mesenchymal cells. Types of morphogenic variations include: Direction and number of cell divisions versus

26 Additional morphogenic variations:
Cell shape changes Cell migrations Cell growth Cell death – (programmed cell death is called apoptosis) Cell membrane changes Secretion changes by cells

27 DevBio9e-Table R.jpg

28 DevBio9e-Table R.jpg

29 DevBio9e-Table R.jpg

30 DevBio9e-Table R.jpg

31 Fate maps of vertebrates at the early gastrula stage
Fate Maps – maps of early developmental stages showing a tracing (or map) of cell lineages through developmental time. Important for both descriptive and experimental embryology. DevBio9e-Fig jpg

32 Edwin Grant Conklin - traced the formation of organs to their origins in the egg cell and embryo. Conklin also investigated the physical mechanism of cell division.

33 Tunicates are marine filter feeders with a sac-like body structure
Tunicates are marine filter feeders with a sac-like body structure. In their respiration and feeding they take in water through an incurrent siphon and expel the filtered water through an excurrent siphon. Most adult tunicates are sessile and attached to rocks or similarly suitable surfaces on the ocean floor. Common names for specific examples of species of tunicates include sea squirts, sea pork or sea tulips.

34 Fate map of the tunicate embryo
This diagram highlights two different ways to represent a fate map… b) Shows a cellular fate map c) Shows a linear fate map DevBio9e-Fig jpg

35 Walter Vogt - the first "fate map" of a vertebrate embryo -- a description of how cells move from their original positions in the early embryo to their ultimate destination.

36 Vital dye staining of amphibian embryos
DevBio9e-Fig jpg

37 Fate mapping using a fluorescent dye
A more modern take on Vogt’s approach: Fluorescence Staining DevBio9e-Fig jpg

38 Hilde Mangold Embryologists who first successfully transplanted embryonic tissues to form chimeric embryos. Hans Spemann

39 Chick resulting from transplantation of a trunk neural crest region from an embryo of a pigmented strain of chickens into the same region of an embryo of an unpigmented strain DevBio9e-Fig jpg

40 Genetic markers as cell lineage tracers
Two more modern takes on ’s Mangold & Spemans’s approach: Genetic Markers DevBio9e-Fig jpg Genetic Markers

41 Fate mapping with transgenic DNA shows that the neural crest is critical in making the bones of the frog jaw Transgenic Labeling DevBio9e-Fig jpg

42 Larval stages reveal the common ancestry of two crustacean arthropods
Similar Appearance Early On Very Different Later DevBio9e-Fig jpg

43 Homologies of structure among human arm, seal forelimb, bird wing, and bat wing
DevBio9e-Fig jpg

44 Development of bat and mouse
DevBio9e-Fig jpg

45 Selectable variation through mutations of genes that work during developmental
DevBio9e-Fig jpg

46 Developmental anomalies caused by genetic mutation
Piebaldism - a disorder caused by the KIT gene which regulates production of the KIT protein which guides proliferation and migration of neural crest cells among other cells. DevBio9e-Fig jpg Individuals affected often experience fertility issues, anemia, underpigmentation of skin and hair, problems with the digestive systems and auditory issues. BE ABLE TO RELATE THIS TO HOW THE NEURAL CREST PROLIFERATES INTO THESE REGIONS.

47 Developmental anomalies caused by an environmental agent
DevBio9e-Fig jpg Environmental exposure to chemicals can affect development in a myriad of ways. The gentleman above was exposed to Thalidamide in-utero, and this resulted in his phocomelia (insufficient limb growth).

48 End.

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