Embryology 1 Flashcards

1
Q

What is a fetus?

A

an orgnaism that breathes no air, does not use the digestive tract and lives in a sterile environment

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2
Q

what is a newborn?

A

an air-breathing organism with a functional GI tract that quickly becomes a colonized by microbial flora

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3
Q

what does the ovaries produce?

A

oocytes, progesterone and estrogen

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4
Q

what are oocytes?

A

female haploid gametes

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5
Q

what is another name for the Uterine tube?

A

fallopian tube

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6
Q

what does the uterine tube receive from the ovaries?

A

oocytes

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7
Q

where is the site where sperm fertilizes the oocyte?

A

Uterine tube

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8
Q

Where is the site where the embryo develops

A

uterus

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9
Q

where is the site where the placenta and membranes develop

A

uterus

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10
Q

what is a placenta?

A

site where the maternal and embryonic vasculatures exchange substances

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11
Q

what does unique mean

A

crossing-over between maternal and paternal chromatids during prophase I to end up with “mixed” chromatids

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12
Q

what does “mixed” mean

A

some paternal, some maternal genes

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13
Q

where does fertilization occur?

A

in the ampulla of the uterine tube

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14
Q

what does ovulation mean?

A

release of a secondary oocyte from ovarian follicle

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15
Q

the ovulated secondary oocyte together with zona pellucida, is externally covered with what

A

cumulus oophorus

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16
Q

cumulus oophorus will rearrange and form what?

A

corona radiata

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17
Q

what happens when the zona pellucida is penetrated by a sperm cell and “injects” its genetic material?

A

it becomes impenetrable and other sperm cells cannot penetrate

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18
Q

what are cells that surround the oocyte, found outside of the zona pellucida?

A

corona radiata

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19
Q

what are gametes?

A

a haploid germ cell

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20
Q

what are sperm?

A

gamete from testes

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21
Q

what are oocytes?

A

gamete from ovaries

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22
Q

what is fertilization?

A

fusion of the pronucleus of the 2 gametes

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23
Q

what is the zona pellucida?

A

protein coat that surrounds an oocyte as well as the early embryo

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24
Q

what is a zygote?

A

a fertilized, diploid oocyte, has not yet divided

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25
Q

what is an embryo?

A

multicellular organism, prior to fetal stage (period from fertilization - end of week 7)

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26
Q

what is a fetus?

A

multicellular organism, from end of embryonic stage to birth

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27
Q

what is a neonate?

A

newborn

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28
Q

what is extraembryonic

A

cells from during development that do not become part of the neonatal organism, but involute or contribute to the fetal membranes

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29
Q

what is morula?

A

approximately 16-cell stage (12-32 cells) of an embryo, no blastocoel

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30
Q

what is blastocyst?

A

a spherical mass of cells that is composed of a trophoblast that surrounds a fluid cavity (blastocoel) and an inner cell mass (embryoblast)

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31
Q

what is cleavage?

A

cell division in the early embryo -> each division does not increase the size of the embryo, instead each division results in a smaller and smaller cells

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32
Q

what is a blastomere

A

a cell that is totipotential and is present during very early develop, product of cleavage

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33
Q

what does totipotential mean

A

a cell that can become any cell

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34
Q

what does implantation mean?

A

occurs when an embryo contacts and then becomes surrounded by the endometrium of the uterus

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35
Q

what is a trophoblast

A

layer of cells on the outside of the sphere (blastomere)

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36
Q

what are embryoblast (inner cell mass)

A

surrounded by the trophoblast, these cells develop into the embryo

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37
Q

what is blastocoel?

A

the fluid filled cavity within the sphere

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38
Q

T or F: the epithelial cells of the uterine tube are equipped with cilia that “wave” in a single direction

A

true

39
Q

ciliary movement increases by what?

A

as progesterone levels increase

40
Q

when does progesterone secretion peak?

A

shortly after ovulation

41
Q

what are the important roles early in development for the zona pellucida

A
  • barrier that ensures that only one sperm fertilizes an oocyte
  • porous - allows communication between the embryo and the maternal reproductive structures
  • protects the embryo from immunologic defenses
  • acts as a signal to help with differentiation of trophoblast cells
  • prevents premature implantation of the embryo
  • prevents the blastomeres from dissociating
42
Q

what happens when the embryo implants too early?

A

it could result in an ectopic pregnancy

43
Q

what day will the embryo “hatch” out of the ZP

A

day 6

44
Q

what are the small apical processes on the endometrial epithelium that contacts with the trophoblast of the blastocyst

A

pinopods

45
Q

once the trophoblast contacts the endometrial epithelium and invades, it forms two layers which are? which one is inner and which one is outer?

A

cytotrophoblast - inner layer
synctiotrophoblast - outer layer

46
Q

what are the important functions of synctiotrophoblast?

A
  • invasion into the endometrial stroma and formation of villi
  • secretion of human chorionic gonadotrophin (hCG)
47
Q

what does human chorionic gonadotropin do?

A

it prevents the shedding of the endometrium by maintaining ovarian secretion of steriod hormones

48
Q

what is the hormone detected in pregnancy tests?

A

hCG

49
Q

as the synctiotrophoblast invades into the stroma, the inner cell mass (embryoblast) differentiates into 2 distinct layers which are?

A

epiblast and hypoblast

50
Q

what will line the blastocystic cavity and form the primary yolk sac?

A

hypoblast

51
Q

Hypoblast is also known as?

A

primary endoderm

52
Q

what is coelom?

A

a fluid-filled cavity (blastocystic cavity)

53
Q

what is gastrulation?

A

the process of forming 3 embryonic germ layers

54
Q

what are the 3 embryonic germ layers?

A

ectoderm, endoderm, mesoderm

55
Q

list the embryonic germ layers from exterior to interior?

A

ectoderm, mesoderm, endoderm

56
Q

what does cephalad mean?

A

towards the head region

57
Q

what does caudad mean?

A

towards the tail region

58
Q

implantation of the embryo is complete at about day what?

A

day 10

59
Q

when implantation is complete, stromal cells undergo what? and is now known as what?

A

decidualization and decidual cells

60
Q

what do decidual cells do?

A

they accumulate glycogen and lipids throughout the uterus
- The decidual cells that the syncytiotrophoblast contact undergo apoptosis, releasing stored nutrients needed for embryonic growth

61
Q

the epiblast enlarges and gives rise to ?

A

amnioblast

62
Q

what are ambioblast

A

cells that surround the developing amniotic cavity

63
Q

what extends around the entire interior surface of the blastocoel

A

hypoblast

64
Q

what cells begin to form and migrate between the hypoblast-derived cells and the cytotrophoblast

A

extraembryonic mesoderm

65
Q

blastocoel turns into what?

A

primary umbilical vesicle/primary yolk sac

66
Q

what forms the bilaminar disk

A

hypoblast and epiblast

67
Q

what is extraembryonic coelom

A

the cavity between the extra-embryonic mesodermal cells

68
Q

as the extraembryonic coelom enlarges and develops, it will develop into what?

A

chorionic cavity

69
Q

extraembryonic coelom completely surrounds the rest of the embryo everywhere except for?

A

the junction of the amniotic cavity and the rest of the chorionic sac, this is the connecting stalkw

70
Q

what later develops into the umbilical cord

A

connecting stalk

71
Q

what are the two layers of extraembryonic mesoderm, separated by the fluid in the extraembryonic coelom?

A

extraembryonic splanchnic mesoderm and extraembryonic somatic mesoderm

72
Q

what does the extraembryonic splanchnic mesoderm surround

A

umbilical vesicle

73
Q

where is the extraembryonic somatic mesoderm?

A

found just underneath the cytotrophoblast, inner lining of the chorionic sac

74
Q

what is chorion

A

the wall of the chorionic sac

75
Q

what are “little lakes” or lacunar networks

A

where syncytiotrophoblast contacts endometrial blood vessels, the blood vessel deteriorates and blood pools

76
Q

what appears at the end of week 2

A

prechordal plate

77
Q

what is the prechordal plate?

A

Thickened area of columnar cells that acts as an organization area, found in the cephalad region of the hypoblast

78
Q

what does induction mean in this case?

A

signaling “episodes” by key areas of the embryo that stimulate differentiation and development of local structures

79
Q

what is the organizer of the head and mouth region, and helps to induce the formation of structures found at the cephalad pole of the embryo

A

hypoblast

80
Q

what is the process by which the 3 germ layers of the embryo are established

A

gastrulation

81
Q

what are the 3 germ layers

A
  • ectoderm
  • mesoderm
  • endoderm
82
Q

during gastrulation, bilaminar embryonic disc becomes what?

A

trilaminar embryonic disc

83
Q

at the beginning of the 3rd week, formation of the ?

A

primitive streak appears

84
Q

what is the primitive streak

A

thickened linear band in the median plane of the dorsal aspect of the embryonic disc

85
Q

where does the primitive streak initiates

A

the caudal region of the epiblast

86
Q

cells at the cephalad end of the primative streak proliferate to form a ?

A

primitive node

87
Q

a narrow groove develops in the primitive streak called

A

primitive groove

88
Q

the primitive groove is continuous with a small depression in the primitive node known as the ?

A

primitive pit

89
Q

Cells leave the deep surface of the streak and form ?

A

mesenchyme

90
Q

what is mesenchyme

A

embryonic connective tissue which forms the supporting tissues of the embryo

91
Q

what forms the intraembryonic or embryonic mesoderm

A

mesoblasts

92
Q

cells from the epiblast, as well as from the primitive node and other parts of the primitive streak displace the hypoblast and form what

A

embryonic endoderm (roof of the umbilical vesicle)

93
Q

what forms the embryonic ectoderm

A

cells in the epiblast