Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Aubrey- Embryology > Embryology Test 1 > Flashcards

Embryology Test 1 Flashcards

1
Q

What is the study of embryo?

A

Embryology

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What includes all developmental processes from conception to death?

A

Ontogeny

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the part from conception to birth or hatching?

A

Embryogeny

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the process by which a cell or part of an embryo become restricted to a given developmental pathway, the point at which a cell becomes committed to specific cell line?

A

Determination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is a complex change involved in progressive specialization of structure and function, often resulting in the formation of luxury moleucles

A

Differentiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Increase in cell numbers

A

Hyperplasia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Increase in cell size

A

Hypertrophy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the six component processes?

A 
Determination
Differentiation
Growth
Morphogenesis
Induction
Integration
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Generation of form or assumption of new shape

A

Morphogenesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What happens in Anaphase I?

A

Homologous chromosomes move to opposite poles
Each homologue consists of two chromatids
Chromatids are not genetically identical because of crossing-over
Daughter cells will be haploid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

An effect one embryonic tissue (inductor) has upon another (responder) such that the development course of the responding tissue is qualitatively changed from what it would have been in the absence of the inductor

A

Induction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

When do the primordial germ cells first appear? Where do they appear?

A

24 days after fertilization

Found in the endodermal layer of yolk sac

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Migration route of primordial germ cells?

A

Yolk sac –> hindgut epithelium
Through dorsal mesentery
Into developing gonads

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Teratomas

A

Growths from misdirected migrating primordial germ cells, contains mixtures of highly differentiated tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Process by which different tissues are brought together and combined to form organs and tissues

A

Integration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the 5 phases of prophase I

A 
Leptotene
Zygotene
Pachytene
Diplotene
Diakinesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Growth

A

Permanent increase in mass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Hyperplasia

A

Increase in cell numbers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What happens in Leptotene?

A

Chromosomes are threadlike
Each chromosome consists of two chromatids
Chromosomes begin to coil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What happens in Zygotene?

A

Homologous chromosomes pair (synapsis)

Synaptonemal complex forms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Determination

A

Process by which a cell or part of an embryo becomes restricted to a given developmental pathway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What happens in Pachytene?

A

Maximum coiling
Tetrads
Crossing-over begins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What happens in Diplotene?

A

Crossing-over continues

Chiasmata are well-defined

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Differentiation

A

Complex changes involved in progressive specialization of structure and function, often resulting in the formation of luxury molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Hypertrophy

A

Increase in cell size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Integration

A

Process by which different tissues are brought together and combined to form organs and tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What happens in Diakinesis

A

Crossing over is complete
Terminalization
Spindle apparatus is in place
Nuclear membrane is disrupted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

At what stage is terminalization?

A

Diakinesis of Prophase I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

When do chromosomes begin to coil?

A

Leptotene of Prophase I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Induction

A

An effect one embryonic tissue (inductor) has on another (responder) such that the development course of the responding tissue is qualitatively changed from what it would have been in the absence of the inductor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Morphogenesis

A

Generation of form or assumption of new shape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

At what stage does the synaptonemal complex form?

A

Zygotene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

During what stages does crossing-over happen?

A

Pachytene & Diplotene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

At what stage in Prophase I is the nuclear membrane disrupted?

A

Diakinesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

At what stage does maximum coiling occur?

A

Pachytene of Prophase I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What happens in Metaphase I?

A

Tetrads line up along equatorial plate

Centromeres do not divide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

At what stage is the Chiasmata well defined?

A

Dipletene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

At what stage do homologous chromosomes move to opposite poles?

A

Anaphase I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

At what stage do homologous chromosomes pair (synapsis)?

A

Zygotene of Prophase I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

At what stage is crossing-over complete?

A

Diakinesis of Prophase I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What happens in Teleophase I?

A

Cytokinesis occurs (usually)
Nuclear membrane reform (maybe)
Spindle apparatus disassembles
Chromosomes may uncoil to varying degrees

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What happens in Prophase II?

A

Chromosomes again condense
Nuclear membranes disappear
Spindle apparatus reforms in each cell
Each chromosome consists of two chromatids
Each daughter cell has one complete set of chromosomes (haploid)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What happens in Metaphase II?

A

Chromosomes line up on equatorial plate?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What happens in Anaphase II?

A

Centromeres divide
Chromosomes move to opposite poles
Each chromosome consists of a single chromatid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

At what stage are there tetrads?

A

Pachytene of Prophase I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

At what stage is the spindle apparatus in place?

A

Diakinesis of Prophase I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Daughter cells in Anaphase I are diploid or haploid?

A

Haploid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

At what stage does the nuclear membrane reform?

A

Teleophase I

Telophase II

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

At what stage does crossing-over begin?

A

Pachytene of Prophase I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

At what stage do tetrads line up along equatorial plate?

A

Metaphase I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

At what stage do chromosomes condense again?

A

Prophase II

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

At what stage does the nuclear membrane disappear?

A

Prophase I and Prophase II

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

At what stage does cytokinesis occur

A

Telephase I

Telophase II

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

At what stage does chromosomes line up on equatorial plate?

A

Metaphase II

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

At what stage does the spindle apparatus reform in the cell?

A

Prophase II

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

In prophase II are the daughter cells haploid or diploid?

A

Haploid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

What happens in Telephase II?

A

Chromosomes uncoil
Cytokinesis is complete
Nuclear membrane reform
End result is four genetically unique haploid daughter cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

At what stage do each chromosome consist of a single chromatid?

A

Anaphase II

Telophase II

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

At what stage do the chromosomes move to opposite poles?

A

Anaphase II

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

At what stage does the spindle apparatus disassemble?

A

Telophase I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

At what stage do centromeres divide

A

Anaphase II

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

Aneuploidy

A

Abnormal number of chromosomes
Nondisjunction
Monosomy
Trisomy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

Euploidy

A

Change in number of complete sets of chromosomes
Monoploidy
Diploidy
Polyploidy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

There are how many germ cells at embryonic midterm?

A

7 million

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

Fetal period characteristics

A

No follicle
Diploid oogonium not surrounded by follicle cells
1 chromatid/ chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

Later Fetal period through birth

A

Diploid primary oocyte
Primordial follicle with a few flattened follicle cells
2 chromatid/ chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

How many primary oocytes are ovulated?

A

400

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

Birth to puberty

A

Diploid primary oocyte
Primary follicle w/ single layer of cuboidal follicle cell
Oocyte & follicle cells are connected via microvilli and gap junctions
Zona pellucida separates primary oocyte from follicular cells
2 chromatids/ chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

After puberty

A

Diploid primary oocyte
Secondary follicle w/ multiple layers of follicle cells & beginning of antrum formation
Membrane granulose surrounds outside of follicle cells
2 chromatids/chromosome
Haploid secondary oocyte + haploid polar body
Tertiary follicle w/ multiple layers of follicle cells, corona radiate and large antrum
Mural granulose cells
Cumulus cells
2 chromatids/ chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

There are how many primary oocytes shortly after birth?

At what stage of meiosis are they arrested in?

A

400,000

Diplotene stage of Prophase I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

Mural granulose cells are found

A

cells between membrane granulose and antrum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

Cumulus cells are found

A

Cells between zona pellucida and antrum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

How many germ cells are present at birth?

A

2 million

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

Oocyte and follicle cells are connected by what 2 things?

A

Microvilli and gap junctions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

What separates the primary oocyte from the follicular cells?

A

Zona pellucida

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

How many primary oocytes survive to puberty?

A

40,000

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

2 factors that lead to meiotic arrest in diplotene?

A

1) High concentration of cAMP from oocyte and follicular cells
- Inactivates MPF
- Leads to meiotic arrest
2) cGMP from follicular cells that inactivates phosphodiesterase 3A in oocyte
- prevents conversion from cAMP to 5’AMP
- maintains high concentration of cAMP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

Ovulation

A

Haploid secondary oocyte with corona radiata and theca cells + haploid polar body
-Granulosa cells develop FSH receptors and LH receptors
-Circulating FSH stimulates granulosa cells to produce estrogen
2 chromatids/chromosome
About 10-12 hrs before ovulation meiosis resumes
1) resumes due to response to LH surge by cumulus cells
2) Cumulus cells shut down gap junctions, cAMP and cGMP can’t get to oocyte
3) no cGMP, activates PDE3a, converts cAMP to 5’AMP
4) Decrease cAMP activates MPF and resumes meiosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

What develops FSH receptors and LH receptors?

A

Granulosa cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

Circuating FSH stimulates granulosa cells to produce what?

A

Estrogen

81
Q

Tertiary follicle consists of what four things?

A

Antrum
Cumulus cells
Zona pellucida
Oocyte

82
Q

Mural granulosa cells

A

Develop FSH receptors

Synthesize aromatase in response to FSH

83
Q

What does aromatase do with concern to ovulation?

A

Aromatase is secreted by mural granulosa cells in response to stimulation by FSH
The aromatase converts testosterone into 17beta-estradiol (estrogens)
Estradiol stimulates the formation of LH receptors on granulosa cells

84
Q

Theca internal cells produce what?

A

Androgens (testosterone)

85
Q

Role of LH

A

LH surge shuts down gap junctions between granulosa cells and oocyte
-causes activation of MPF and resumes meiosis

LH surge, LH binds to receptors on follicular cells
Activation of adenyl cyclase
Progesterone secretion by follicle cells
Activation of collagenase enzyme
Release of oocyte
86
Q

Stages of Spermatogenesis

A 
Primordial germ cell (2N)
Spermatogonia (2N)
-Type A (stem cells)
-Type B (leave mitotic cell to enter meiotic cycle under influence of retinoic acid)
Primary spermatocyte (2N)
-First maturation division (meiosis I)
Secondary spermatocyte (N x 2 cells)
-Second maturation division (meiosis II)
Spermatids (N x 2 cells)
87
Q

Influence of what causes type B spermatogonia cells to leave the mitotic cell and enter meiotic cycle?

A

Retinoic acid

88
Q

Testosterone is produced by what?

A

Theca internal cells

89
Q

Sertoli cells are located where?

A

Seminiferous tubules within the testis

90
Q

Cells of Leydig
Location?
Function?

A

Interstitial cells in testis

Produce testosterone

91
Q

Functions of sertoli cells (6)

A
  1. Physical support & maintenance
  2. Maintain and coordinate spermatogenesis
  3. Secrete estrogen, inhibin, androgen binding protein & anti-mullerian factor
  4. Maintain blood-testis barrier
  5. Secrete tubular fluid
  6. Phagocytize residual bodies of sperm cells
92
Q

Sperm histones

A

proamines

93
Q

What sertoli cells also called?

A

Sustentacular cells

94
Q

Blood Testis Barrier with Sertoli cells

A

Sertoli cells form an immunological barrier between the forming sperm cells and the rest of the body and spermatogonia

1) surface adhesion complexes bind to sertoli
2) SAC brake down & release spermatids in lumen
3) Laminin frag from SAC plus cytokines and proteninases break down tight junctional proteins
- Developing spermatocytes move closer to lumen
4) Testosterone stimulates formation of new barrier

95
Q

What breaks down the blood testis barrier?

A

Laminin fragments from surface adhesion complex plus cytokines and proteinases

96
Q

What stimulates formation of a new blood-testis barrier closer to basal lamina?

A

Testosterone

97
Q

Testosterone effect on Sertoli cells & secondary sex characteristics

A

Testosterone is carried by blood to sertoli and secondary sex tissues
FSH binds to receptors on Sertoli cells
-Sertoli converts testosterone to estrogen and synthesizes leydig cells stimulatory factor
-Produce androgen binding factor
-Binds to testosterone and carries it to seminferious vesicles

98
Q

Ovulation occurs when?

Roles of FSH & LH on ovulation?

A

Ovulation occurs on day 14 of the ovarian cycle
The stimulus for ovulation is a rise in levels of FSH and a sharp peak in LH
(ant. pit)

99
Q

What components of the graafian follicle form the corpus luteum?

A

The residual theca and granulosa cells proliferate and form a large glandular structure called the corpus luteum

100
Q

Outer part of graafian follicle that remains is made of what and secretes what?

A

Thecal cells

Secrete progesterone

101
Q

Fate of corpus luteum without fertilization

A

Corpus luteum regresses and levels of progesterone and estradiol decrease resulting in beginning of next menstral cycle

102
Q

Inhibin is released by?

What does it do?

A

Released by granulose cells

Inhibits secretion of gonadotropins, esp. FSH, resulting in regression of corpus luteum

103
Q

What is the role of corpus luteum in endometrial cycle?

A

In pregnancy, the corpus luteum continues to produce progesterone which maintains that early embryo until the placenta begins to produce sufficient hormones to maintain pregnancy

104
Q

Proliferative phase

A
  1. Endometrial growth increases the endometrial thickness from 1-2 mm to 8-10 mm by day 14
  2. Blood vessels & glands grow
  3. Cells that initiate growth come from bases of the glands that formed previous endometrium that were deep enough to survive the loss
  4. Proliferation phase is due to increase in levels of estradiol secreted by the grandulose cells of the developing ovarian follicle
  5. Near the end of this phase is sharp rise in estradiol levels
105
Q

Vasoconstriction by what?

A

Prostaglandins

106
Q

Secretory phase

A
  1. During the phase levels of estrogen decrease & the endometrial growth stops
  2. Mucous glands develop more fully and begin secretion
  3. The spiral arterioles in this area expand & heavily vascularize the area
  4. The secretory phase is controlled by rising levels of progesterone, secreted by both the granulose & theca cells of the ovarian follicle
107
Q

Graffian follicle prior to ovulation

A

Mature Graafian follicle

  • expansion of follicle (FSH & LH)
  • Thickening of outer layers of follicle
  • Rupture of follicle wall (24 hr after surge)
108
Q

Fertilization age

A

Date age of embryo at time of fertilization

109
Q

Menstrual age

A

Date age is from start of last menstrual period, 2 weeks greater

110
Q

Rapid egg transport is through where and what hormone is required?

A

Isthmus

Progesterone

111
Q

What contributes to semen and with what?

A

Seminal vesicles: fructose and prostaglandins
-Fructose provides energy
Prostate: citric acid, Zn, Mg, Phosphate

112
Q

pH of upper vagina

A

4.3

Adjusts to 7.2 for sperm

113
Q

What is the optimal pH for sperm motility and is where?

A

6.0-6.5 in the cervix

114
Q

Fertilization in the oviduct occurs where?

A

Ampulla

115
Q

What is the purpose of capacitation? What occurs

A

Required for sperm to undergo acrosomal reaction
-Occurs inside uterine in isthmus
-Requires binding of sperm to tubule epithelium
-Involves:
1. Removal of cholesterol from sperm surface
(acts to inhibit premature capacitation)
2. Removal glycoproteins (epididymus)

116
Q

Where does capacitation occur in the female tract?

A

Inside the uterine tube in Isthmus

117
Q

Major enzyme of acromsome?

A

Hyaluronidase

118
Q

Penetration of Corona Radiata (4)

A
  1. Fusion of the outer acrosomal membrane with the sperm plasma membrane creates portals through which the contents of the acrosome can be released
  2. Fragmentation of fused acrosomal membrane and plasmalemma of the sperm results in the release of acrosomal enzymes
  3. Hyaluronidase is one the major enzymes in the acrosome
  4. Swimming movements of spermatozoa help in the penetration through the corona radiata
119
Q

Function of ZP3

A

Zp3 is one of four glycoproteins that make up the ZP
Attachment of sperm to the ZP is mediated by ZP3 protein
ZP3 protein stimulates acrosomal reaction in mammals
1. Acts through a G protein in the sperm plasma membrane
(Leads to influx of calcium through sperm plasma membrane, exchange of sodium and hydrogen increase pH, then penetration)

120
Q

What is the most important enzyme involved in the penetration of the zone pellucida

A

Acrosin (serine proteinase)
aka zona lysin
Remains attached to the portion of the acrosomal membrane that fuses to the remaining sperm plasmalemma and overlies nucleus
Digest small hole through ZP

121
Q

Fast block

A

Consists of a rapid depolarization of egg plasmalemma
-70 to +10 mV within 2-3 sec (to min)
Fast block temporarily prevents polyspermy and allows time for the egg to establish slow block

122
Q

Slow block

A

Most characterized by release of polysaccharides from the cortical granules located just under the plasmalemma of the egg

  • Polysaccharides enter perivitelline space (between plasmalemma and the zona pellucida) and become hydrated
  • Hydration produces a swelling that increases the width of the perivitelline space
123
Q

Role of phospholipase C zeta in metabolic activation of the egg following fertilization?

A

Metabolic activation of egg is initiated by release of calcium within egg cytoplasm in response to introduction of phospholipase C zeta by sperm

124
Q

Pronucleus

A

Is the nuclear material of the head of the spermatozoan (male pronucleus) or of the oocyte (female pronucleus) after the oocyte has been penetrated by spermatozoan

  • Each pronucleus carries a haploid set of chromosomes
  • The male pronuclei consists of decondensed nuclear material
  • A pronuclear membrane, derived from endoplasmic reticulum of the egg, typically forms around the female chromosomal material
125
Q

What introduces phospholipase C zeta to the cytoplasm?

A

Sperm

126
Q

Zygote

A

Is the term used to denote the single-cells stage of which the male and female pronuclei have fused together and share a common membrane, establishing the diploid chromosome number

127
Q

Inside-Out Hypothesis

A

Fate of balstomere is determined by its position within the embryo, not from intrinsic properties

128
Q

Cell polarity Model

A 
Fate of blastomere depends on plane of cell division during cleavage
Parallel
-outer: trophoblast (polar)
-inner: inner cell mass (apolar)
Perpendicular
-Both daughter cells trophoblast
129
Q

Trophoblast cells are what layer

Forms what?

A

Outer layer cells

Forms extra embryonic structures including placenta

130
Q

Inner Cell Mass are what layer

Forms what?

A

Inner mass of cells

Forms embryo proper plus some extra embryonic structures

131
Q

What makes the blastocyst polarized?

A

The eccentric placement of blastocoel and inner cell mass

  1. Embryonic pole marks the pole of the blastocyst where the inner cell mass is located
  2. Abembryonic pole marks the opposite side
132
Q

Invertebrates and non-mammalina genetic control of cleavage

A

Early control of cleavage is through gene products transcribed from the material genome and embryonic gene products often do not appear until after blastulation

133
Q

Mammalian embryo genetic control of cleavage

A

Maternal gene products are produced but generally degraded by the 2 cell stage
By the four cell stage, most transcription is via the embryonic genome

134
Q

Cdx-2

A
  1. Essential for trophoblast cell differentiation

2. Antagonistic toward Oct-4

135
Q

Oct-4

A
  1. Expressed in developing oocytes and zygote
  2. Required to permit cleavage to proceed to 2-cell stage
  3. Expressed in all morula cells
  4. May play a role in the maintenance of the undifferentiated state
136
Q

Nanog

A
  1. Produced by inner cells in the late morula stage
  2. Maintains integrity of inner cell mass along with Oct4
  3. Without nanog, inner cell differentiate into endoderm
  4. Without Oct4, inner cell differentiate into trophoblast
137
Q

Sox2

A
  1. First expressed in 8 cell stage

2. Along with Oct-4 it helps to control regulation of genes involved in differentiation

138
Q

Genomic imprinting

A

Is differential gene expression depending on whether a chromosome is inherited from the male or female parent

  • It refers to observations that expression of certain genes derived from the egg differs from the expression of the same genes derived from the sperm
  • Due to DNA methylastion differences in sperm and eggs
139
Q

Methylation of DNA

A
  1. In mammals methylation is erased in the germ cells of each generation and then re-established in the course of gamete formation
  2. Sperm and eggs undergo different levels of methylation resulting in the differential expression of male and female alleles in the offspring
140
Q

Prader Willi

A

mental retardation
Obese
Mutation from father
Chrom 15

141
Q

Angelmann syndome

A

Uncontrolled muscle movement
Large mouth
Seizures
Mother mutation

142
Q

Barr bodies

What do they tell us about a person’s genome?

A

Barr bodies are inactivated X chromosome

Show genome is female

143
Q

Regulation

A
  1. Refers to ability of embryo to compensate for removal of structures or for addition of structures
  2. At the cellular level, this means that the fates of cells in a regulative system are not irretrievably fixed, and the cells can still respond to environmental cues
144
Q

Identical twins

A

Product of single fertilized egg

More commonly arise by subdivision of the inner cell mass in a blastocyst or splitting of the epithelial epiblast

145
Q

Dizygotic twins

A

Product of fertilization of 2 ovulated eggs, mechanism for formation involves endocrine control of ovulation

146
Q

Common attachment site for parasitic twins

A

Oral region
Mediatinum
Pelvis

147
Q

Bateson’s rule?

A

When duplicated structures are joined during critical development stages, one structure is the mirror image of the other

148
Q

Functions of Zona pellucida

A
  1. It promotes maturation of the oocyte and follicle
  2. Serves as a barrier that normally allows only sperm of same species to access the egg
  3. It initiates the acrosomal reaction
  4. After fertilization, the modified zona pellucida prevents any additional spermatozoa from reaching the zygote
  5. During the early stages of cleavage, it acts as a porous filter through which certain substances secreted by the uterine tube can reach the embryo
  6. Because it lacks histocompatibility (leukocyte) antigens, the zona pellucida serves an as immunological barrier between the mother and antigenitically different embryo
  7. It prevents blastomeres of the early cleavage embryo from dissociating
  8. It facilitate the differentiation of trophoblastic cells
  9. It normally prevents premature implantation of the cleaving embryo into the wall of the uterine tube
149
Q

Ectopic pregnancy

Common occur?

A

Implantation other than uterine wall
Most common is a tubal pregnancy
-Ampulla
-Next isthmus

150
Q

Homeobox

A

The highly conserved sequence of 180 nucleotides in the gene that encode the homeodomain

151
Q

Homeodomain

A

Highly conserved domain of 60 amino acids

A homeodomain is a type of helix loop helix region

152
Q

X inactivation is brought about by the action of what?

A

Xist

153
Q

What prevents the mother’s immune system from recognize the embryo as a foreign body?

A

Interleukin-2

154
Q

Homeobox-containing genes

A

Are activated in a 3 to 5 direction (opposite of transcription)

155
Q

Helix-loop-Helix genes

A

Codes for basic helix loop helix transcription factors
Basic regions of proteins bind to DNA
Involved in homodimerization and heterodimerization
Important in myogenesis

156
Q

Zinc finger transcription factors

A

These proteins have zinc ions bound to polypeptides chain that cause the chain to form finger-like projections that can be inserted into the DNA helix
Gene families: Sox and WT1

157
Q

Sox Genes

A

Sox transcription factors have a high-mobility group domain that binds to minor groove on DNA helix rather than major groove
Sox gene family includes SRY gene

158
Q

WT1

A

Is important for the development of the embryonic kidney and the adult kidney
It takes name from child kidney tumor

159
Q

Egg polarity Genes

A

Egg polarity genes are important in the establishment of the dorsal-ventral and anterior posterior axis in the fruit fly

160
Q

Genes that establish the dorsal ventral axis

A

Dorsal, Cactus, Toll

161
Q

Genes that establish the anterior posterior axis

A

Bicoid, Nanos, Hunchback

162
Q

Morphogen

A

A protein that varies in concentration and causes different developmental responses as a result of the concentration differences

163
Q

Dorsal protein

A

Expressed in ovary

164
Q

Cactus protein

A

Expressed in the ovary and binds to the dorsal protein and traps it in the cytoplasm

165
Q

Toll

A

Expressed in ovary and leads to the degradation of the cactus protein, allowing the dorsal protein to move into the nuclei of the ventral cells

166
Q

Bicoid protein

A

Expressed in the ovary, regulates expression of genes responsible for anterior structures and stimulates hunch back (forms a gradient with high concentration at anterior end)

167
Q

Nanos

A

Expressed in the ovary and regulated the expression of genes responsible for posterior structures. Inhibits translation of hunchback mRNA

168
Q

Hunchback

A

Forms a gradient with high concentration at anterior end

169
Q

Segmental genes

A
  1. These are 25 segmentation genes that are transcribed after fertilization; so they do not exhibit a genetic maternal effect
  2. Expression of the segmentation genes is regulated by the Bicoid and Nanos protein gradients
  3. Three classes of segmentation gene include:
    a. Gap genes
    b. pair rule genes
    c. segment-polarity genes
170
Q

Gap genes

A

Delete adjacent segemnts

171
Q

Pair rule genes

A

Delete same part of pattern in every other segment

172
Q

Segment-polarity genes

A

Affect polarity of segment

173
Q

Homeotic genes

A
  1. Determine the identity of individual segments
  2. Products of homeotic genes activate other genes that encode these segment-specific characteristics
  3. Expressed after fertilization
  4. Activated by concentration of products of gap, pair-rule, and segment polarity gens
  5. Contain homeobox
  6. Two major groups of homeotic genes
    - Antennapedia complex (Hox genes)
    - Bithorax complex (Hox genes)
174
Q

Antennapedia complex

A

Affects development of head and thorax

175
Q

Bithorax complex

A

Affects development of posterior thorax and abdominal segments

176
Q

Signaling Factor families

A

Transforming Growth Factor Beta superfamily
Fibroblast Growth Factor Family
Hedgehog family
Wnt family

177
Q

Transforming Growth Factor Beta Superfamily

A 
TGF-beta
Activin
Inhibin
Mullerian inhibiting substance
Decapentaplegic
Vg1
BMP
Nodal
Glial cell line neurotrophic factor
Lefty
178
Q

Hedgehog Family

A

Desert
Indian
Sonic hedgehog

179
Q

Process of lateral inhibition

A

1) Type of signaling between a dominant cell and neighboring cells
2) Dominant cell refers to a cell in a population that begins to differentiate along a particular path
3) Dominant cell expresses Delta signaling molecules on its cell membrane
4) Delta then binds to Notch receptors on neighboring cells and via the Delta-Notch pathway represses genes in the neighboring cells

180
Q

In the absence of Wnt, what is bound to an intracellular destruction complex within the target cell (wnt pathway)

A

beta-catenins

181
Q

Role of nanog in the establishment of the epiblast and hypoblast

A

Cells entering inner cell mass earliest express nanog and are destined to become epiblast cells

182
Q

Role of Gata6 in the establishment of the epiblast and hypoblast

A

Cells entering inner cell mass later express gata6 and are destined to become hypoblast cells

183
Q

Roles of Wnt and TGF-beta on formation of primitive streak?

A

Begin the process of induction of primitive streak

184
Q

What are the three classical molecular markers expressed by nodal cells

A

Chordin
Goosecoid
Hepatic nuclear factor-3 beta (Foxa-2)

185
Q

Chordin

A
  1. Signaling molecules associated with the node
  2. Involved in neural induction and expression of nodal of the left side of the embryo, key element in setting of left-right asymmetry
186
Q

Goosecoid

A

Homeodomain transcription factor
Activates chord in, noggin, and other genes
If ectopically expressed, stimulates formation of secondary body axis

187
Q

Hepatic nuclear factor-3 beta (Foxa-2)

A

Transcription factor
Establishment of midline structures cranial to node
In absence, notochord and the floor plate fail to form

188
Q

Bottle cells

What role do they play

A
  1. Epithelial cells head towards primitive groove and change shape to bottle shape, thrust themselves through primitive groove
  2. Breaks down cell adhesion molecules becomes free and irregular shaped
  3. Transforming cells are freed from the basal lamina and lose E-cadherins
  4. Epitehlial mesenchymal cell transformation is correlated with expression of transcription factors snail
  5. changes in the shape of a cell as it migrates along the epiblast through the primitive streak (bottle cell) and away from the groove as a mesenchymal cell that will become part of the mesodermal germ layer.
    (same cell can later assume epithelial configuration as part of somite)
189
Q

Role of E-caherin and N-cadherin in epithelial mesenchymal transition

A

1) Prior to induction ectoderm expresses both E-cadherin and N-CAM
2a) After neural tube induction, overlying ectoderm only expresses E-cadherin
2b) After neural tube induction, neural tube ectoderm expresses N-CAM and N-cadherin

190
Q

What transcription factor is correlated with epithelial mesenchymal cell transformation

A

Snail

191
Q

Source and role of Cerebrus-like signaling molecule in development of anterior posterior axis

A
  1. From the anterior visceral endoderm

2. inhibits development of posterior structures

192
Q

DSource and role of Dkk-1 signaling molecule in development of anterior posterior axis

A
  1. From Anterior visceral endoderm
  2. Blocks Wnt
  3. Inhibits development of posterior structures
193
Q

Effects of Foxa-2 on early primitive streak stage

A

Multiple targets
Establishment of primitive node
Initiates notochord functions
Establishes midline structures cranial to node

194
Q

In the late primitive streak stage, what signaling molecule is necessary for normal head function?

A

Cerebrus- related 1

Origin: prechordal plate

195
Q

In the late primitive streak stage, what signaling molecule is released from the primitive streak activate Hox gene?

A

Retinoid acid, Wnt, and FGF

Targets Cdx to activate Hox

196
Q

Experiments for neural induction

A
  1. The dorsal lip of the blastopore was grafted beneath the belly ectoderm of another host
  2. Result: secondary nervous system and body axis formed in the area of the graft
  3. Hensen’s node from one avian embryo to another induces the formation of secondary neural tube
  4. The dorsal lip is the organizer because of its ability to stimulate the formation of a secondary body axis
  5. In higher vertebrate, the primitive node and the notochordal process at as the neural inductor and the overlying ectoderm is the responding tissue
197
Q

What is the first sign of asymmetry in early developemnt

A

Involves the beating of cilia around the primitive node

198
Q

Role of Nodal

A

Symmetry breaking molecules in the left side of the embryo
Swept to left side of primitive node by ciliary current
Stimulates mulitple gene expression pathways via: Pitx-2

199
Q

Lefty1

A

Left side of the primitive streak
Expresed on left side of the embryo
Blocks diffusion of molecules to the right side

Aubrey- Embryology (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions