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28 Cards in this Set
- Front
- Back
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Describe the phases of fertilization.
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1. Sperm penetrates CORONA RADIATA then ZONA PELLUCIDA- acrosome releases enzymes to digest
2. Fusion of plasma membrane of sperm and egg followed closely with completion of meiosis 2 (egg) 3. Formation of male pro-nucleus with male and female replicating 4. Fusion of pro-nuclei |
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Cleavage
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In early embryology:
rapid mitotic divisions of zygote to produce BLASTOMERES |
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What is COMPACTION and when does it occur
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at 9-cell stage:
blastomeres change shape and atachements eventually form MORULA |
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Morula
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12-32 blastomere embryo
enters the uterus 3 days after fertilization |
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BLASTOCYST
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4 days post-fertilization, BLASTOCYSTIC CAVITY forms in morula
inner cell mass surrounded by TROPHOBLAST 6-7 days post-fertilization will "hatch" from zona pelucida |
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Trophoblast
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the thin outer cell later of a blastocyst
gives rise to embryonic part of placenta |
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Embryoblast
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the inner cell mass of the blastocyst
gives rise to embryo |
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Describe where implantation occurs and the position of the blastocyst.
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implantation usually occus on the uperior portion of the posterior uterine wall
inner cell mass/ embryoblast should be oriented closest to the endometrium (with trophoblast in between) |
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After implantation, the TROPHOBLAST differentiates. When does this occur and into what catagories?
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day 6 followign implantation, TROPHOBLAST differentiates into:
1. CYTROPHOBLAST- inner layer of trophoblast 2. SYNCYTIOTROPHOBAST- a multinucleate group of cells forming outer layer; makes enzymes to invade endometrium |
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Cytotrophoblast
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CYTOtrophoblast
inner layer of trophoblast formed 6 days following implantation/ 12 days post-fertilization |
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Syncytiotrophoblast
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SYNCYTIOtrophoblast
outer layer of trophoblast (multinucleate) produces enzymes to invade endometrium produces hCG to sustain the CORPUS LUTEUM |
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What produces hCG to sustain the corpus luteum should pregnancy occur?
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SYNCYTIOtrophoblast
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Hypoblast
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the deep layer of embryoblast; primary endoderm
delaminates after 7 days implantation; faces blastocystic cavity |
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How are nutrients exchanged between mother and embryo in the immediate 1-2 weeks following implantation?
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Diffusion
endometrial epithelium cells undergo programmed cell death and syncytiotrophoblast engulfs their nutrients |
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When is formation of germ layers?
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Third week
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When is the formation of bilaminar embryonic disc?
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2nd week
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Lacunae
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cavities formed in the synctiotrophoblast
fill with maternal blood to facilitate diffusion of nutrients- blood provides nutrients for EMBRYONIC DISC |
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Decidual cells
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specialized cells in endometrium set for programmed cell death
engulfed by the syncytiotrophoblast for nutrients |
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Primordial Uteroplacental Circulation
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established w/ communication between maternal endometrial capillaries and lacunae
O2 maternal blood into lacunae via endometrial arteries and out via endometrial veins |
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How long does it take to complete embryo implantation in endometrium?
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10 days post-implantation
2 weeks post-fertilization |
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Closing plug
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site on implantation of embryo in endometrium
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Decidual reaction
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immuno-privledged site in endometrium for conceptus
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Placenta previa
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implantation of the embryo at the neck of the uterus/ interior of cervix
placenta "before" fetus |
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Prechordal Plate
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PRECHORDAL PLATE
a thickened area of the HYPOBLAST; indicates future location of the mouth appears on d.14 |
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Epiblast
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forms the floor of the amniotic cavity; continuous with amnion
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Hypoblast
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d.7- delamination of the deep inner cell mass
forms the rof of the UMBILICAL VESICLE |
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Amnion
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continuous with the EPIBLAST; forms the roof of the amniotic cavity
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Embryonic disc
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2 weeks post-fertilization
the cell layer consisting of the HYPOBLAST and the EPIBLAST |
