{"id":611,"date":"2015-08-17T17:20:54","date_gmt":"2015-08-17T17:20:54","guid":{"rendered":"http:\/\/sites.msudenver.edu\/haysc\/?page_id=611"},"modified":"2015-08-17T17:20:54","modified_gmt":"2015-08-17T17:20:54","slug":"answers-1-bio-3220-early-development","status":"publish","type":"page","link":"https:\/\/sites.msudenver.edu\/haysc\/biology-courses\/comparative-vertebrate-anatomy-bio-3220\/answers-1-bio-3220-early-development\/","title":{"rendered":"Answers-1, BIO 3220, Early Development"},"content":{"rendered":"

C. EARLY DEVELOPMENT<\/strong><\/p>\n

1. Define gamete.
\nGamete \u2013 sex cell<\/p>\n

2. Compare microlecithal, mesolecithal, and macrolecithal eggs. What does lecithal mean?
\nMicrolecithal \u2013 small amount of yolk; found in amphioxus and eutherians
\nMesolecithal \u2013 medium amount of yolk; found in lampreys, dipnoans, chondosteans and amphibians
\nMacrolecithal \u2013 large amount of yolk; found in most fish, reptiles, birds, monotremes
\nLecithal \u2013 yolk<\/p>\n

3. Compare isolecithal and telolecithal eggs.
\nIsolecithal \u2013 even yolk distribution
\nTelolecithal \u2013 uneven yolk distribution<\/p>\n

4. Define animal and vegetal pole.
\nAnimal pole \u2013 the region of the egg with the highest metabolic activity
\nVegetal pole \u2013 the region of the egg with the highest concentration of yolk<\/p>\n

5. Describe the various membranes\/enclosures around different eggs.
\nVitelline membrane \u2013 a thin non-cellular membrane secreted by the oocyte and follicular cells that surround an oocyte and that will form the fertilization membrane if sperm penetration occurs
\nJelly \u2013 protective covering of eggs; for example, amphibian eggs
\nCapsule \u2013 outermost encapsulating structure of the egg, consisting of one or more membranes, the protective shell
\nShell \u2013 hard protective covering of eggs
\nAlbumin \u2013 the egg white of bird eggs formed in the oviduct before the addition of the shell
\nCorona Radiata \u2013 a layer of protective follicle cells derived from the cumulus oophorus surrounding the zona pellucida of an oocyte after ovulation
\nZona Pellucida \u2013 a translucent non-cellular membrane surrounding a mammalian egg through which sperm must penetrate in order for fertilization to occur<\/p>\n

6. Distinguish and give and example of oviparous, viviparous, and ovoviviparous animals.
\nOviparous \u2013 producing eggs that develop and hatch outside the body of the female, as in many fish, birds, and many amphibians
\nViviparous \u2013 bringing forth living young, rather than laying eggs; producing live young from within the body of the parent female, as in most mammals
\nOvoviviparous – retaining the eggs within the body of the female in a brood chamber in which the development of the embryo takes place, as in Squalus<\/p>\n

7. Define zygote.
\nZygote – Cell formed from the union of an egg and a sperm; fertilized egg; joined gametes<\/p>\n

8. Compare cleavage, blastula formation, and gastrulation in microlecithal, mesolecithal, and macrolecithal eggs.
\nMicrolecithal eggs \u2013 cleavage is equal; blastula is a hollow ball of cells with a blastocoel; gastrulation process is involution
\nMesolecithal eggs \u2013 cleavage is unequal; blastocoel is displaced into animal pole; yolk impedes mitotic process; more mitosis at animal pole; gastrulation process is epiboly
\nMacrolecithal eggs \u2013only mitotic division at animal pole; blastoderm forms at animal pole; gastrulation process is delamination<\/p>\n

9. Name the 3 germ layers and list tissues derived from each of the layers.
\nEndoderm \u2013 first forms as outgrowth of inner cell mass in blastocyst in mammals; grows down to surround the blastocoel which then becomes the yolk sack; gives rise to digestive, liver, lungs, pancreas, thyroid gland, other glands
\nEctoderm \u2013 cells of inner cell mass thicken and begin to multiply forming first the neural tube; gives rise to CNS, sense organs, mammary glands, sweat glands, skin, hair, hooves
\nMesoderm \u2013 separate from the ectoderm and fills space between endoderm and ectoderm; gives rise to circulatory, skeletal, muscle, reproductive tracts, kidneys, urinary ducts<\/p>\n

10. Explain the process of neurulation and organogenesis.
\nNeurulation begins with the formation of a neural plate, a thickening of the ectoderm caused when cuboidal epithelial cells become columnar. Changes in cell shape and cell adhesion cause the edges of the plate fold and rise, meeting in the midline to form a tube. The cells at the tips of the neural folds come to lie between the neural tube and the overlying epidermis. These cells become the neural crest cells.
\nDuring organogenesis considerable cell interactions and rearrangements occur which produces the tissues and organs of the body. Many cells undergo migrations from their place of origin during organogenesis and many organs contain cells from more than one germ layer.<\/p>\n

11. Define the following terms \u2013
\nInvolution \u2013 enfolding; tucking in
\nEpiboly \u2013 streaming in; ex. cells move into middle of cell in gastrulation
\nChordomesoderm \u2013 cells that form notochord during gastrulation
\nEpimere = dorsal mesoderm \u2013 the dorsal portion of the mesoderm of a chordate embryo that gives rise to the dermatone, myotome, and sclerotome
\nSomite \u2013 block of dorsal mesodermal cells adjacent to the notochord during vertebrate organogenesis. These transient structures define the segmental pattern of the embryo, and subsequently give rise to vertebrae and ribs, dermis of the back, and skeletal muscles of the back, body wall and limbs
\nMesomere = intermediate mesoderm \u2013 layer of the mesoderm that gives rise to kidney tubules and associated ducts
\nHypomere = lateral plate mesoderm \u2013 layer of the mesoderm that gives rise to the somatic, splanchnic, somatopleure, splanchnnopleure, and coelom layers
\nSomatic mesoderm \u2013 layer of the lateral plate mesoderm (hypomere) that contributes to bone of the girdles and limbs, muscles of body wall
\nSplanchnic mesoderm \u2013 layer of the lateral plate mesoderm (hypomere) that contributes to muscles of the heart, blood vessels and other visceral structures
\nSomatopleure \u2013 layer of the lateral plate mesoderm (hypomere) that forms the muscles and connective tissue of body wall
\nSplanchnnopleure \u2013 layer of the lateral plate mesoderm (hypomere) that forms the muscles and connective tissue of the gut tube
\nCoelom \u2013 layer of the lateral plate mesoderm (hypomere) that forms the body cavity
\nPrimitive streak \u2013 thickening of the epiblast cell layer caused my movement of mesodermal cells into the blastocoel; this structure is characteristic of avian, reptilian and mammalian gastrulation
\nMesenchyme \u2013 mesodermal tissue that forms connective tissue and blood and smooth muscles; mesoderm \u201con the move,\u201d detaches and moves to another location
\nNotochord \u2013 a flexible rodlike structure in embryos of higher vertebrates, from which the spinal column develops
\nBlastoderm \u2013 the layer of cells formed by the cleavage of a fertilized mammalian egg, which later divides into the three germ layers from which the embryo develops
\nDelamination \u2013 the process by which the blastoderm forms 2 layers, the epiblast and the hypoblast; the epiblast becomes the ectoderm, the hypoblast becomes the endoderm
\nArchenteron \u2013 the central cavity of the gastrula, which ultimately becomes the intestinal or digestive cavity
\nDermatome \u2013 the part of a mesodermal somite from which the dermis develops
\nMyotome \u2013 the segment of a somite in a vertebrate embryo that differentiates into skeletal muscle
\nSclerotome \u2013 the portion of a somite that proliferates mesenchyme which migrates about the notochord to form the axial skeleton and ribs<\/p>\n

12. List the amniote classes.
\nReptiles, birds and mammals<\/p>\n

13. Define body stalk and umbilical cord.
\nBody stalk \u2013 a band of mesoderm that connects the yolk and the embryo
\nUmbilical cord \u2013 a cord that connects the fetus to the maternal placenta in viviparous mammals<\/p>\n

14. Name the main extraembryonic membranes and discuss their functions.
\nBody stalk \u2013 connects the yolk and the embryo
\nYolk sac \u2013 in birds, to nourish embryo; in mammals atrophies, but source of blood cells and primordial germ cells
\nAmnion \u2013 non-vascular, fluid-filled protective cushion
\nChorion \u2013 outermost membrane of embryo; attachment to mother
\nAllantois \u2013 for gas exchange and waste receptacle
\nPlacenta \u2013 allows for better waste removal and nutrient uptake; primarily a yolk sac in marsupials<\/p>\n","protected":false},"excerpt":{"rendered":"

C. EARLY DEVELOPMENT 1. Define gamete. Gamete \u2013 sex cell 2. Compare microlecithal, mesolecithal, and macrolecithal eggs. What does lecithal mean? Microlecithal \u2013 small amount of yolk; found in amphioxus and eutherians Mesolecithal \u2013 medium amount of yolk; found in … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":270,"featured_media":0,"parent":580,"menu_order":0,"comment_status":"closed","ping_status":"open","template":"","meta":{"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"footnotes":""},"class_list":["post-611","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/sites.msudenver.edu\/haysc\/wp-json\/wp\/v2\/pages\/611","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sites.msudenver.edu\/haysc\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/sites.msudenver.edu\/haysc\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/sites.msudenver.edu\/haysc\/wp-json\/wp\/v2\/users\/270"}],"replies":[{"embeddable":true,"href":"https:\/\/sites.msudenver.edu\/haysc\/wp-json\/wp\/v2\/comments?post=611"}],"version-history":[{"count":0,"href":"https:\/\/sites.msudenver.edu\/haysc\/wp-json\/wp\/v2\/pages\/611\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/sites.msudenver.edu\/haysc\/wp-json\/wp\/v2\/pages\/580"}],"wp:attachment":[{"href":"https:\/\/sites.msudenver.edu\/haysc\/wp-json\/wp\/v2\/media?parent=611"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}