Lesson 4 - Early Craniate Morphogenesis Flashcards

1
Q

bilaterally symmetrical chordates with indeterminate cleavage with mouth not arising from blastopore

A

deuterostomes

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2
Q

closes relatives of chordates

A
  • Hemichordates
  • Echinoderms
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3
Q
  • believed to be closer relatives of chordates but still being debated on
  • believed to have branched off
A

Cephalochordates or Tunicates

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4
Q

show resemblance to each other in neuroanatomy and biochemistry

A
  • cephalochordates
  • vertebrates
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5
Q

Egg types: amount of yolk

A
  1. microlecithal
  2. mesolecithal
  3. macrolecithal
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6
Q
  • very little yolk
  • amphioxus, therian mammals
A

microlecithal

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7
Q

microlecithal example

A
  • amphioxus
  • therian mammals
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8
Q
  • moderate amount of yolk
  • amphibians
A

mesolecithal

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9
Q

mesolecithal example

A

amphibians

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10
Q
  • large amount of yolk
  • reptiles, monotremes
A

macrolecithal

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11
Q

macrolecithal example

A
  • reptiles
  • monotremes
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12
Q

Egg types: yolk distribution

A
  1. isolecithal
  2. telolecithal
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13
Q
  • yolk is evenly distributed in the cytoplasm
  • seen in microlecithal egg
A

isolecithal

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14
Q

where is isolecithal seen

A

microlecithal egg

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15
Q
  • yolk is concentrated in one pole (vegetal pole)
  • seen in mesolecithal and macrolecithal eggs
  • opposite pole contains the nucleus and relatively yolk free cytoplasm
A

telolecithal

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16
Q

where is telolecithal seen

A
  • mesolecithal
  • macrolecithal eggs
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17
Q

two pole in telolecithal

A
  1. vegetal pole
  2. animal pole
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18
Q

where yolk is concentrated

A

vegetal pole

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19
Q

opposite pole containing the nucleus and relatively yolk free cytoplasm

A

animal pole

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20
Q

Ways offsprings are produced by interal fertilization

A
  1. oviparity
  2. viviparity
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21
Q
  • animals that lay eggs (spawn)
  • eggs contain sufficient amount of yolk and albumen to support the development into a free-living organism that is able to take food orally
A

oviparous

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22
Q

fully formed when hatched
(birds)

A

oviparous macrolecithal

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23
Q

example of fully formed when hatched

A

birds

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24
Q

young hatch in larval stage
(frog)

A

oviparous mesolecithal

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25
Q

example of young hatch in larval stage

A

frog

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26
Q

young hatch in a free-living and self-nourising stage
(amphioxus)

A

oviparous microlecithal

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27
Q

example of young hatch in a free-living and self-nourising stage

A

amphioxus

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28
Q

animals that give birth to offsprings

A

viviparous

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29
Q

different types of viviparity

A
  1. ovoviviparity
  2. euviviparity
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30
Q
  • mother provides only protection and oxygen
  • nourishment stored in the egg
A

ovoviviparity

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31
Q

example of ovoviviparous animal

A

spiny dogfish shark

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32
Q

embryos are dependent on maternal tissues for all nourishment, oxygen, excretion of wate products of metabolism

A

euviviparity

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33
Q
  • egg may be fertilized and the young may develop in the ovarian follicle or ovarian cavity
  • trophotaeniae
A

viviparous teleosts

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34
Q

where do viviparous teleosts develop

A
  • ovarian follicle or
  • ovarian cavity
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35
Q
  • External, umbilical cord-like structure present in members of the family Goodeidae and some other fish groups responsible for transfer of nutrients between an adult female and her internally-developing young.
  • May still be attached to fry at birth
A

trophotaenia

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36
Q

meaning of word trophotaenia

A

trophe = nutrition
taenia = band

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37
Q

Different types of fertilization

A
  1. internal fertilization
  2. external fertilization
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38
Q
  • fertilization takes place within the body of the female (viviparous craniates)
  • intromittent organ is needed to introduce sperm into the female reproductive tract
  • eggs are covered by impenetrable shell before being extruded (reptiles)
A

internal fertilization

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39
Q

what is needed in internal fertilization in order for the sperm to be introduced into the female reproductive tract

A

intromittent organ

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40
Q
  • millions of sperm cells are shed over the eggs as the eggs are being extruded
  • oviparous fishes, frogs, and toads
A

external fertilization

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41
Q

example of external fertilization

A

oviparous fishes, frogs, toads

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42
Q

describes sexually reproducing fishes that develop mature gonads containing oocytes and spermatozoa

A

Hermaphroditism

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43
Q

considerably different from juveniles and adults

A

larvae

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44
Q

Stages in Early Development

A
  1. gamete formation
  2. fertilization
  3. cleavage
  4. gastrulation
  5. organ formation
  6. growth, tissue specialization
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45
Q
  • repeated mitotic cell division of the zygote initiated by the union of two mature sex cells or gametes
  • embryo experience little or no growth in size
A

cleavage or segmentation

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46
Q
  • formed during cleavage
  • multicelled and hollow sphere
A

blastula

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47
Q

cells resulting from the early cleavage division of the ovum

A

blastomeres

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48
Q

fluid filled cavity in a blastula

A

blastocoele

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49
Q

cells of the blastula form an epithelial (covering) layer

A

blastoderm

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50
Q

Types of Cleavage

A
  1. holoblastic cleavage
  2. meroblastic cleavage
  3. discoidal cleavage
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51
Q
  • entire egg undergoes cellularization, and yolk platelets are either absent (e.g., in mammals) or present as cytoplasmic inclusions that partition among cells (e.g., in amphibians)
  • mitotic furrow pass through the entire zygote from animal to vegetal pole
A

holoblastic cleavage

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52
Q

mitotic furrow in holoblastic cleavage

A

pass through the entire zygote from animal to vegetal pole

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53
Q

holoblastic cleavage in microlecithal eggs

A

blastomeres are approximately of equal size

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54
Q

holoblastic cleavage in mesolecithal eggs

A

yolk laden cells in vegetal pole divide more slowly and are larger

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55
Q
  • where yolk is plentiful macrolecithal)
  • cleavage furrows form, but do not progress into the yolk.
  • mitotic furrow is slowed and only a portion of the cytoplasm in the animal pole is cleaved
  • Species that exhibit this type of cleavage are birds, insects, fish, and reptiles
A

meroblastic cleavage

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56
Q

mitotic furrow in meroblastic cleavage

A
  • slowed
  • only a portion of the cytoplasm in the animal pole is cleaved
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57
Q
  • extensive yolk material at the vegetal pole remains undivided by mitotic furrows
  • cleavage restricted to a cap of dividing cells at the animal pole
A

discoidal cleavage

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58
Q

mitotic furrow in discoidal cleavage

A

do not divide extensive yolk material at vegetal pole

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59
Q

where is discoidal cleavage restricter to

A

cap of dividing cells at animal pole

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60
Q

Mechanisms of cleavage

A
  1. localized expansion of cortex
  2. increased stiffness of the cortical cytoplasm
  3. increased tangential force activity in the cortex
  4. contractile nature of regions near the cortex
  5. formation of new cell membrane from the subcortical sytoplasm
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61
Q

cleavage follows __

A

fertilization

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62
Q

when is the cleavage called blastula

A

after it produced over 100 blastomeres

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63
Q
  • continued cleavage produces this
  • it is a microscopic ball or cluster of cells formed through cell division very early in the embryonic development that occurs after the formation of a zygote through fertilization but before the blastocyst stage.
A

morula

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64
Q

no. of cells in morula

A

16 cells

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65
Q

no. of cells in blastocyst

A

70-100 cells

66
Q

two-cell, four-cell, eight-cell

A

occurs in uterine tube

67
Q

morula and blastocyst

A

occurs in uterus

68
Q

make use of the abundant cytoplasm of the fertilized egg as the cells rapidly divide without changing the total volume

A

pre-embryonic cleavages

69
Q

what results in the rearrangment of the cells in the mammalian bastula to two layers

A

blastocyst

70
Q

parts of the blastocyst

A
  1. trophoblast
  2. inner cell mass
  3. blastocoel
71
Q

give rise to extraembryonic structures, including the placenta

A

trophoblast

72
Q

gives rise to the embryo

A

inner cell mass

73
Q

very early stage of development when the zygote becomes a ball of cells with a fluid filled center, and an inner mass of cells.

A

blastulation

74
Q

next step in which the inner mass of cells forms three distinct germ layers.

A

gastrulation

75
Q

cells that have the capacity to self-renew by dividing and to develop into the three primary germ cell layers of the early embryo and into extra-embryonic tissues such as the placenta

A

Totipotent stem cells

76
Q

consists of totipotential cells

A

epiblast layer

77
Q

visible feature which represents the site of cell migration to form the additional layers

A

primitive streak

78
Q

gastrulation rearranges the embryo into a __ __

A

triploblastic gastrula

79
Q

what are the embryonic germ layers

A
  1. ectoderm
  2. mesoderm
  3. endoderm
80
Q

produces a triploblastic embryo with an archenteron

A

frog gastrulation

81
Q
  • digestive cavity of an embryo during the gastrula stage
  • will eventually develop into the complete gastrointestinal (GI) tract
A

archenteron

82
Q

“germinal localization” and it is a marker of the dorsal side of the fertilized egg, the future embryo, and the adult

A

gray crescent

83
Q

what is formed in the invagination during frog gastrulation

A

dorsal lip of blastopore

84
Q

cells on the dorsal surface roll over the edge of the dorsal lip and into the interior of the embryo

A

involution

85
Q

patch of vegetal cells (endoderm) that remains exposed in the blastopore after the formation of the ventral lip during gastrulation.

A

yolk plug

86
Q

when is the primitive streak visible

A

during week three

87
Q

stimulates neurulation in the ectoderm after its development

A

notochord

88
Q

process that leads to the development of the central nervous system, starting around 21 days postfertilization in humans

A

neurulation

89
Q

the process by which the neural tube, the precursor of the brain and spinal cord, is shaped from the neural plate.

A

Primary neurulation

90
Q

form the neural tube

A

folds of the groove

91
Q

what is formed from the anterior portion of neural tube

A

basal plate

92
Q

what is formed from the posterior portion of neural tube

A

alar plate

93
Q

what is formed from the center of neural tube

A

neural canal

94
Q

when do the ends of the neural tube close

A

conclusion of fourth week of gestation

95
Q

either of the openings to the exterior at the anterior and posterior ends of the neural tube of a vertebrate embryo

A

neuropore

96
Q

how to know dorsal blastopore lip

A

where archenteron is

97
Q

how to know ventral blastopore lip

A

where blastocoel is

98
Q

what is formed when the neural plate folds outward

A

neural groove

99
Q

what is known as the 4th germ layer

A

neural crest cells

100
Q

what is formed from neural crest cells

A

components of the PNS

101
Q

separates neural plate and ectoderm

A

neural plate border

102
Q

referred to the neural plate once its joined

A

neural crest

103
Q

what disconnects the neural crest from the epidermis or ectoderm

A

closure of neural tube

104
Q

what happens to the notochord

A
  • degenerates
  • persists as nucleus pulposus
105
Q

precursor of axial skeleton and skeletal muscles

A

somites

106
Q
  • mesoderm found lateral to the neural tube
  • distinct from the mesoderm found more internally in the embryo
A

paraxial mesoderm

107
Q

somites develop into what

A
  • dermis
  • skeletal muscle
  • vertebrae
108
Q

four components of somites

A
  1. sclerotome
  2. myotome
  3. dermatome
  4. syndetome
109
Q

the part of each somite in a vertebrate embryo giving rise to bone or other skeletal tissue

A

sclerotome

110
Q

forms some of the skeletal muscle

A

myotome

111
Q

forms the connective tissues, including the dermis

A

dermatome

112
Q
  • gives rise to the axial tendons of the body
  • located between neighboring sclerotome and myotome, at the future site of connection between bone and muscle
A

syndetome

113
Q

process of formation of organs from three germ layers

A

Organogenesis

114
Q

ectoderm layer contributes to

A
  1. epidermis of skin, and derivatives
  2. epithelial lining of mouth and rectum
  3. cornea and lens of eyes
  4. nervous system
  5. adrenal medulla
  6. tooth enamel
  7. epithelium of pineal and pituitary glands
115
Q

endoderm layer contributes to

A
  1. epithelial lining of digestive tract (except mouth and rectum)
  2. epithelial lining of respiratory system
  3. pancreas
  4. thyroid, parathyroid
  5. thymus
  6. lining of urethra, urinary bladder, and reproductive systems
116
Q

mesoderm layer contributes to

A
  1. notochord
  2. skeletal and muscular systems
  3. circulatory and lymphatic systems
  4. excretory systems
  5. reproductive system (except germ cells)
  6. dermis of skin
  7. lining of body cavity
  8. adrenal cortex
117
Q

solution to reproduction in a dry environment

A

amniote embryo

118
Q

what do amniote embryo have

A

extra amniotic membrane

119
Q

shelled eggs

A

reptiles and birds

120
Q

uterus

A

placental mammals

121
Q

cleavage in avian development

A

meroblastic, or incomplete

122
Q

embryo-forming portion of an egg with discoidal cleavage usually appearing as a small disc on the upper surface of the yolk mass.

A

blastodisc

123
Q

will keep embryo attached to the yolk

A

yolk stalk

124
Q
  • occurs at the eight-cell stage of mammalian development
  • results to cells tighlty adhering to one another
A

compaction

125
Q

Mammalian development
Step 1: about 7 days after fertilization

A
  • blastocyst reaches the uterus
  • inner cell mass is surrounded by the trophoblast
126
Q

Mammalian development:
surrounds the inner cell mass

A

trophoblast

127
Q

what does the inner cell mass form

A
  • epiblast
  • hypoblast
128
Q

where does the embryo develop almost entirely

A

from epiblast

129
Q

Organogenesis begins with the formation of what?

A
  • neural tube
  • notochord
  • somites
130
Q

mesoderm underneath the neural tube

A

chordamesoderm

131
Q

paraxial mesoderm is called what in vertebrates

A

unsegmented mesoderm

132
Q

paraxial mesoderm is called what in chick embryos

A

segmented mesoderm

133
Q

comparison of chordates and non-chordates:
notochords

A

chordates: present
non-chordates: absent

134
Q

comparison of chordates and non-chordates:
dorsal hollow nerve cord

A

chordates: dorsal hollow single nerve cord
non-chordates: ventral, solid, double

135
Q

comparison of chordates and non-chordates:
pharyngeal gill slits

A

chordates: present
non-chordates: absent

136
Q

comparison of chordates and non-chordates:
heart

A

chordates: ventral
non-chordates: dorsal

137
Q

comparison of chordates and non-chordates:
post anal tail

A

chordates: present
non-chordates: absent

138
Q

embryos possess extraembryonic membranes

A

amniotes (reptiles, birds, mammals)

139
Q

embryos without extraembryonic membranes

A

anamniotes (fishes, amphibians)

140
Q
  • composite organ formed from maternal and fetal tissues
  • functions as a site for exchange between parent and embryo
A

placenta

141
Q

chief extraembryonic membrane

A
  1. yolk sac
  2. amnion
  3. chorion
  4. allantois
142
Q
  • surrounds the yolk, empties into the midgut and usually lines the endoderm
  • highly vascular, vitelline arteries and veins are continuous with the circulatory channel within the embryo
A

yolk sac

143
Q
  • inner sac next to the fetus
  • make up the amniotic sac
A

amnion

144
Q
  • surrounds the embryo withtin the amniotic sac
  • metabolic water from embryonic tissuse
  • buffers the fetus against mechanical injury
  • helps prevent dessication in embryos
A

amniotic fluid

145
Q
  • outer sac next to uterine wall
  • lies in intimate relationship with either the eggshell or the lining of the mother’s uterus
  • keeps the fetus in communication with its source of oxygen and in viviparous animals, its source of nutrients
A

chorion

146
Q

very thin, soft, usually unpigmented hair that is sometimes found on the body of a fetus or newborn

A

Lanugo

147
Q
  • extension of the hindgut of the amniote embryos
  • function in excretion and sometimes in respiration
A

allantois

148
Q
  • when allantois comes in contact with the inner surface of the chorion
  • respiratory organ in reptiles and monotremes
A

chorioallantoic membrane

149
Q
  • when the allantois comes in direct contact with the lining of the maternal uterus
  • respiratory organ, site of transfer of nutrients and metabolic waste
A

chorioallantoic placenta

150
Q

kinds of placenta based on composition

A
  1. yolk sac placenta
  2. choriovitelline placenta
  3. chorioallantoic placenta
151
Q
  • yolks sac serves as part of a placenta because of the absence of amnion, chorion, or allantois
  • viviparous amphibians and fishes
A

yolk sac placenta

152
Q

yolk sac and chorion in direct contact with maternal uterus

A

choriovitelline placenta

153
Q
  • chorion and allantois in direct contact with maternal uterus
  • mammals have umbilical cord connecting the fetus with the placenta
A

chorioallantoic placenta

154
Q

Kinds of placenta based on intimacy of relationship between fetal and maternal tissues

A
  1. nondeciduous or contact placenta
  2. deciduous placenta
155
Q
  • in simple contact with the uterine lining (endometrium)
  • no shedding of the lining at birth
A

contact or nondeciduous placenta

156
Q
  • chorionic villi becomes rooted into the endometrium
  • at birth, the fetal parts of the placenta disengages and the deciduas (invaded part of the uterine lining) is shed
A

deciduous placenta

157
Q

Kinds of placenta based on chorionic villi distribution

A
  1. cotyledonary placenta
  2. zonary placenta
  3. discoidal placenta
  4. diffuse placenta
158
Q
  • in isolated patches
  • sheep, cow
A

cotyledonary placenta

159
Q
  • in a band encricling the sac
  • cat, dog, seal
A

zonary placenta

160
Q
  • in a single large discoidal area
  • brown bear, human
A

discoidal placenta

161
Q
  • diffuse over the entire surface of the chorion
  • pig
A

diffuse placenta