The Questions of Developmental Biology

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Table 3.1. Photolyase activity correlated with exposure of eggs to ultraviolet radiation in 10 amphibian species Species Photolyase activity a Mode of egg-laying Exposure to sunlight Plethodon dunni
The Developmental Mechanics of Cell Specification An embryo's environment may be a tide pool, a pond, or a uterus. As we saw above, the embryo interacts with its environment, and its developmental trajectory can be guided by information from its surroundings. On a smaller scale, the environment of an embryonic cell consists of the surrounding tissues within the embryo, and the fate of that cell (for instance, whether it becomes part of the skin or part of the lens) often depends upon its interactions with other components of its immediate "ecosystem." Thus, a second research program of experimental embryology studies how interactions between embryonic cells generate the embryo. The development of specialized cell types is called differentiation (Table 3.2). These overt changes in cellular biochemistry and function are preceded by a process involving the commitment of the cell to a certain fate. At this point, even though the cell or tissue does not appear phenotypically different from its uncommitted state, its developmental fate has become restricted. Table 3.2. Some differentiated cell types and their major produts Cell type Differentiated cell product Specialized function of cell Keratinocyte (epidermal Keratin Protection against abrasion, desiccation cell) Erythrocyte (red blood Hemoglobin Transport of oxygen cell) Lens cell Crystallins Transmission of light B lymphocyte Immunoglobulins Antibody synthesis T lymphocyte Cell-surface antigens (lymphokines) Destruction of foreign cells; regulation of immune response Melanocyte Melanin Pigment production Pancreatic islet cells Insulin Regulation of carbohydrate metabolism Leydig cell ( ) Testosterone Male sexual characteristics Chondrocyte (cartilage Chondroitin sulfate; type II collagen Tendons and ligaments cell) Osteoblast (bone-forming Bone matrix Skeletal support cell) Myocyte (muscle cell) Muscle actin and myosin Contraction Hepatocyte (liver cell) Serum albumin; numerous enzymes Production of serum proteins and numerous enzymatic functions Neurons Neurotransmitters (acetylcholine Transmission of electrical impulses epinephrine, etc.) Tubule cell ( ) of hen Ovalbumin Egg white proteins for nutrition and protection of oviduct embryo Follicle cell ( ) of insect Chorion proteins Eggshell proteins for protection of embryo ovary The process of commitment can be divided into two stages (Harrison 1933; Slack 1991). The first stage is a labile phase called specification. The fate of a cell or a tissue is said to be specified when it is capable of differentiating autonomously when placed in a neutral environment such as a petri dish or test tube. (The environment is neutral with respect to the developmental pathway.) At this stage, the commitment is still capable of being reversed. The second stage of commitment is determination. A cell or tissue is said to be determined when it is
Page 1 and 2: PART 1. Principles of development i
Page 3 and 4: PART 2: Early embryonic development
Page 5 and 6: 15. Lateral plate mesoderm and endo
Page 7 and 8: Hox Genes: Descent with Modificatio
Page 9 and 10: The question of growth. How do our
Page 11 and 12: Embryonic homologies One of the mos
Page 13 and 14: absent (Figure 1.16A). Over 7000 af
Page 15 and 16: Such growth, in which the shape is
Page 17 and 18: One way to search for the chemicals
Page 19 and 20: 2 3 hours as adults, and they must
Page 21 and 22: for the following spring's breeding
Page 23 and 24: VADE MECUM Amphibian development. T
Page 25 and 26: The formation of a cap is a complex
Page 27 and 28: In Chlamydomonas, recognition occur
Page 29 and 30: organism with two distinct and inte
Page 31 and 32: Aggregation is initiated as each of
Page 33 and 34: The mathematics of such oscillation
Page 35 and 36: gonidia to undergo a modified patte
Page 37 and 38: Sponges develop in a manner so diff
Page 39 and 40: Embryology provides an endless asso
Page 41 and 42: Environmental sex determination Sex
Page 43: Protection of the egg by sunscreens
Page 47 and 48: Autonomous specification was first
Page 49 and 50: In postulating this model, Weismann
Page 51 and 52: Insofar as it contains a nucleus, e
Page 53 and 54: Other tissues may use the same grad
Page 55 and 56: will give rise to its particular or
Page 57 and 58: Sydney Brenner (quoted in Wilkins 1
Page 59 and 60: The results of their experiments we
Page 61 and 62: This observation led Steinberg to p
Page 63 and 64: into a single layer of cells (Takei
Page 65 and 66: 6. In conditional specification, th
Page 67 and 68: 3. Geneticists had to explain pheno
Page 69 and 70: These events are not the normal rou
Page 71 and 72: differentiated; each of them contai
Page 73 and 74: federal proscription of human cloni
Page 75 and 76: ecombinase enzymes are active only
Page 77 and 78: In situ hybridization But where was
Page 79 and 80: damaged.) The second primer is adde
Page 81 and 82: By using the appropriate restrictio
Page 83 and 84: These homozygous mutant mice lacked
Page 85 and 86: Phenotype Manipulation This technol
Page 87 and 88: The second approach is candidate ge
Page 89 and 90: developmental genetics is different
Page 91 and 92: This gene consists of the following
Page 93 and 94: In addition to these basal transcri
Page 95 and 96:
Enhancers are critical in the regul
Page 97 and 98:
The third functional region of MITF
Page 99 and 100:
A fourth enhancer sequence, located
Page 101 and 102:
The discovery of the human globin L
Page 103 and 104:
The results of this procedure are o
Page 105 and 106:
In vertebrates, the presence of met
Page 107 and 108:
chromatin that remains condensed th
Page 109 and 110:
Second, knocking out one Xist locus
Page 111 and 112:
types of cells (Kleene and Humphrey
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(Sxl) gene,* while the autosomes pr
Page 115 and 116:
Table 5.3. Some mRNAs stored in ooc
Page 117 and 118:
determine the anterior-posterior ax
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6. Cell-cell communication in devel
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The inducing tissue does not need i
Page 123 and 124:
Instructive and permissive interact
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mouth, whereas the frog tadpole pro
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are utilized throughout the animal
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includes the TGF-β family, the act
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The RTK spans the cell membrane, an
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members of this family: the C. eleg
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The Wnt pathway Members of the Wnt
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The Hedgehog pathway is extremely i
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A series of mutations has been foun
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The Nature of Human Syndromes As we
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vertebral column deformities, myopi
Page 145 and 146:
The mammalian homologue of CED-4 is
Page 147 and 148:
In the absence of Notch gene transc
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extracellular matrix (Figure 6.32).
Page 151 and 152:
mammary gland tissue. The binding o
Page 153 and 154:
In some cells, gene transcription r
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PARTE 2. Early embryonic developmen
Page 157 and 158:
The means by which sperm are propel
Page 159 and 160:
The sperm released during ejaculati
Page 161 and 162:
Lying immediately beneath the plasm
Page 163 and 164:
The mechanisms of chemotaxis differ
Page 165 and 166:
Once the sea urchin sperm has penet
Page 167 and 168:
Removal of these threonine- or seri
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undergo the acrosomal reaction with
Page 171 and 172:
Gamete Fusion and the Prevention of
Page 173 and 174:
The fast block to polyspermy. The f
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envelope to expand and become the f
Page 177 and 178:
The calcium ions responsible for th
Page 179 and 180:
Thus, the conversion of NAD + to NA
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eticulum (McPherson et al. 1992). T
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cAMP-dependent protein kinase activ
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These cells divide to form embryos
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(Figure 7.34; Elinson and Rowning 1
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6. In many species, eggs secrete di
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One consequence of this rapid cell
Page 193 and 194:
Table 8.1. Karyokinesis and cytokin
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provides a classification of cleava
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This occurred at precisely the time
Page 199 and 200:
These rapid and invariant cell clea
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The identities of the signaling mol
Page 203 and 204:
Ingression of primary mesenchyme Fu
Page 205 and 206:
But these guidance cues cannot be s
Page 207 and 208:
lastocoel wall (Dan and Okazaki 195
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The orientation of the cleavage pla
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stage, the remaining cells divide n
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embryos can produce these cells, bu
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Early Development in Tunicates Tuni
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(or inactivating) specific genes. T
Page 219 and 220:
occur under laboratory conditions.
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the germ cells. Using fluorescent a
Page 223 and 224:
Conditional specification As we saw
Page 225 and 226:
eggs. Coda This chapter has describ
Page 227 and 228:
9. The genetics of axis specificati
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Following cycle 13, the oocyte plas
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Thus, at the end of germ band forma
Page 233 and 234:
Classic embryological experiments d
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posterior region of the unfertilize
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Further studies have strengthened t
Page 239 and 240:
The Hunchback protein also works wi
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transcription factor to activate an
Page 243 and 244:
The gap genes The gap genes were or
Page 245 and 246:
Table 9.2. Major genes affecting se
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The development of the normal patte
Page 249 and 250:
However, the mechanism by which the
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As we saw above, the gap gene and p
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can substitute for Ultrabithorax an
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The Translocation of Dorsal Protein
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The Gurken signal is received by th
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This fate map is generated by the g
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first glimpses of the multiple leve
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10. Early development and axis form
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While these cells are dividing, num
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The next phase of gastrulation invo
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Black and Gerhart (1985, 1986) let
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The convergent extension of the dor
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During early gastrulation, three ro
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Spemann concluded from this experim
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Hans Spemann and Hilde Mangold: Pri
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We will take up each of these quest
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Moreover, the injection of exogenou
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These Nodal-related proteins will a
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The diffusible proteins of the orga
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Follistatin. The fourth organizer-s
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Frzb and Dickkopf. Shortly after th
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Moreover, when dorsal blastopore li
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The relationship between these thre
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Nodal protein activates expression
Page 297 and 298:
11. The early development of verteb
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Gastrulation in Fish Embryos The fi
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If one conceptually opens a Xenopus
Page 303 and 304:
Left-right axis formation Little is
Page 305 and 306:
thereby forming the secondary hypob
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This region, the germinal crescent,
Page 309 and 310:
Axis Formation in the Chick Embryo
Page 311 and 312:
The mechanisms for neural induction
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*Arendt and Nübler-Jung (1999) hav
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Compaction The fifth, and perhaps t
Page 317 and 318:
Modifications for development withi
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The ectodermal precursors end up an
Page 321 and 322:
These include the genes for transcr
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Experimental analysis of the hox co
Page 325 and 326:
Kessel and Gruss (1991) found this
Page 327 and 328:
Mice homozygous for an insertion mu
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7. In birds, gravity is critical in
Page 331 and 332:
This tissue forms the amnionic sac
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12. The central nervous system and
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surrounding them. As much as 50% of
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Cell wedging is intimately linked t
Page 339 and 340:
Fig 12.6 Human neural tube closure
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The anterior-posterior axis The ear
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Ventral patterning of the neural tu
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The time of this vertical division
Page 347 and 348:
layer (Wallace 1999). Each Purkinje
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However, if these cells are transpl
Page 351 and 352:
Neuronal Types The human brain cons
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Neurons transmit electrical impulse
Page 355 and 356:
Development of the Vertebrate Eye A
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In addition, there are numerous Mü
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are shed and are replaced by new ce
Page 361 and 362:
Just as there is a pluripotent neur
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13. Neural crest cells and axonal s
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The Trunk Neural Crest Migration pa
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Recognition of surrounding extracel
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However, D. J. Anderson's laborator
Page 371 and 372:
Neural crest cells from rhombomeres
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the aortic arch arteries and the se
Page 375 and 376:
Soon afterward, the expression patt
Page 377 and 378:
Ericson and colleagues (1996) have
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That it must be a sort of a surface
Page 381 and 382:
the G growth cone acts abnormally,
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Guidance by diffusible molecules Ne
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There is some reciprocity in scienc
Page 387 and 388:
The activity of the synapse release
Page 389 and 390:
Growth of the retinal ganglion axon
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The complicated nerve fiber circuit
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Snapshot Summary: Neural Crest Cell
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Fetal Neurons in Adult Hosts In 197
Page 397 and 398:
Somites give rise to the cells that
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Eph signaling is thought to mediate
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(The dermis of other areas of the b
Page 403 and 404:
Muscle cell fusion The myotome cell
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The mechanism of intramembranous os
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mitochondrial energy potential (Sha
Page 409 and 410:
Mutations in FGFR1 can cause Pfeiff
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These buds eventually separate from
Page 413 and 414:
Step 2: The metanephrogenic mesench
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Step 5: Conversion of the aggregate
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6. The two myotome regions are spec
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The Heart The circulatory system is
Page 421 and 422:
This fusion occurs at about 29 hour
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Formation of Blood Vessels Although
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networks of each organ arise within
Page 427 and 428:
In some instances, angiogenesis may
Page 429 and 430:
This became apparent when experimen
Page 431 and 432:
Blood and lymphocyte lineages. Figu
Page 433 and 434:
Chick cells are readily distinguish
Page 435 and 436:
In mammalian embryos, food and oxyg
Page 437 and 438:
*In some infants, the septa fail to
Page 439 and 440:
As Figure 15.27 shows, the stomach
Page 441 and 442:
The surfactant enables the alveolar
Page 443 and 444:
In mammals, the size of the allanto
Page 445 and 446:
inhibits liver formation (Figure 15
Page 447 and 448:
Moreover, as will be detailed in Ch
Page 449 and 450:
These cells secrete the paracrine f
Page 451 and 452:
Induction of the apical ectodermal
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The progress zone: The mesodermal c
Page 455 and 456:
The mechanism by which Hox genes co
Page 457 and 458:
Thus, while the Hox gene expression
Page 459 and 460:
Charité and colleagues (1994) have
Page 461 and 462:
Between the time when the cell's de
Page 463 and 464:
Snapshot Summary: The Tetrapod Limb
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This environmental view of sex dete
Page 467 and 468:
The cells of the seminiferous tubul
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into the mesenchyme, but stay near
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There was a strict correlation betw
Page 473 and 474:
Wnt4: a potential ovary-determining
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Anti-müllerian duct hormone Anti-M
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in another (see Jacklin 1981; Bleie
Page 479 and 480:
Chromosomal Sex Determination in Dr
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The sex-lethal gene as the pivot fo
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Doublesex: The switch gene of sex d
Page 485 and 486:
It is not known whether the tempera
Page 487 and 488:
18. Metamorphosis, regeneration, an
Page 489 and 490:
There are no ipsilateral (same-side
Page 491 and 492:
Organ-specific response to thyroid
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The more T 3 receptors a tissue has
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Other species, such as A. tigrinum,
Page 497 and 498:
Metamorphosis in Insects Types of i
Page 499 and 500:
On one side of the sac, the epithel
Page 501 and 502:
During the first larval instar, the
Page 503 and 504:
central region producing the Wingle
Page 505 and 506:
The molecular biology of hydroxyecd
Page 507 and 508:
Since its discovery in 1954, when B
Page 509 and 510:
How do they regain the ability to d
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It is probable that during normal r
Page 513 and 514:
The head activator gradient. The ab
Page 515 and 516:
*The tradition of leaving one's boo
Page 517 and 518:
However, recent studies have indica
Page 519 and 520:
Moreover, if a mutation occured in
Page 521 and 522:
Snapshot Summary: Metamorphosis, Re
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19. The saga of the germ line We be
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In the nematode C. elegans, the ger
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When ultraviolet light is applied t
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Fibronectin is likely to be an impo
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Germ cell migration in birds and re
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EG Cells, ES Cells, and Teratocarci
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come together and are then separate
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The distal tip cell extends long fi
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The initiation of spermatogenesis d
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ecause the flagellum is beginning t
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A partial catalogue of the material
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When a specific 340-base sequence f
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Oocyte chromosomes can be incubated
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The structure of the meroistic ovar
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Periodically, a group of primordial
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Following ovulation, the luteal pha
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20. An overview of plant developmen
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oth the embryo and the mature sporo
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*A small weed in the mustard family
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should provide information on the e
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of hormones. In scarlet runner bean
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embryos demonstrate that isolated p
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When the shoot emerges from the soi
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etween nodes is called an internode
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flowering patterns among the over 3
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genes, class D genes are now being
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Table 21.1. Specific settlement sub
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Predictable Environmental Differenc
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Diapause Many species of insects ha
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The hindwing pigments of the short-
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Ferguson and Joanen (1982) speculat
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Predator-Induced Defenses One survi
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3. Antigens are presented (usually
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the ipsilateral eye. The situation
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*The importance of substrates for l
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Thus, most abnormal embryos are spo
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Retinoic acid as a teratogen In som
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Another pathway to apoptosis involv
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Whether heavy maternal alcohol cons
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Some scientists, however, say that
Page 603 and 604:
Chains of causation Whether in law
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Snapshot Summary: The Environmental
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One could emphasize the common desc
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The search for the Urbilaterian anc
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Hox Genes: Descent with Modificatio
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Changes in Hox gene transcription p
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But within the crustacean lineages,
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Changes in Hox gene number The numb
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Homologous Pathways of Development
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The gradient of Dpp concentration f
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Modularity: The Prerequisite for Ev
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Such a trait would be selected for
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*The lack of such transitional form
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Coevolution of ligand and receptor
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Evidence for this mathematical mode
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It is difficult for a mutation to a
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The population genetics model conta
Page 637 and 638:
However, once one adds development
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A partial list of genes active in h
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The Questions of Developmental Biology

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