The Pre-Embryonic Period Flashcards
<p>How does once cell become a multicellular body?</p>
<p>Growth, Morphogenesis, Differentiation</p>
<p>What does morphogenesis involve?</p>
<p>Creating lots of cells in the right place at the right time</p>
<p>What is the result of morphogenesis?</p>
<p>The development of form and structure</p>
<p>Why is differentiation needed?</p>
<p>For specialisation for function</p>
<p>What does differentiation allow?</p>
<p>Certain groups of cells to specialise for a common function</p>
<p>What are the 3 stages from fertilisation to birth?</p>
<p>- Pre-embryonic
- Embryonic
- Fetal</p>
<p>When is the pre-embryonic period?</p>
<p>Weeks 1-2</p>
<p>When is the embryonic period?</p>
<p>Weeks 3-8</p>
<p>Why is the embryonic period such a critical period?</p>
<p>All structures and systems of the body are made</p>
<p>When is the foetal period?</p>
<p>Weeks 9-38</p>
<p>What happens in the foetal period?</p>
<p>The focus is on growth and physical maturation of systems</p>
<p>When are pregnancy weeks calculated from?</p>
<p>LMP, i.e. conception weeks +2</p>
<p>How long is a term pregnancy?</p>
<p>40 weeks</p>
<p>What happens in the pre-embryonic period?</p>
<ul> <li>Cleavage</li> <li>Compaction</li> <li>Implantation begins</li> </ul>
<p>What is happening in cleavage?</p>
<p>Mitotic division</p>
<p>Why is cleavage significant?</p>
<p>Because have established a new individual</p>
<p>What is formed from cleavage?</p>
<p>Morula</p>
<p>What is the morula?</p>
<p>A clump of cells</p>
<p>What happens in compaction?</p>
<p>The formation of a blastocyst</p>
<p>What is implantation?</p>
<p>The process by which the blastocyst makes contact with the endometrium of the uterus</p>
<p>What does implantation begin?</p>
<p>The establishment of the pregnancy</p>
<p>Where is the oocyte released from?</p>
<p>The ovary</p>
<p>What happens to the oocyte once it’s been released?</p>
<p>It travels along the Fallopian tubes</p>
<p>Where is the oocyte fertilised?</p>
<p>Ampulla</p>
<p>What fertilises the oocyte?</p>
<p>Sperm</p>
<p>What is the ampulla of the fallopian tubes?</p>
<p>The fan bit just above the ovary</p>
<p>What is the fertilised oocyte called?</p>
<p>The zygote</p>
<p>Where is the ideal site for implantation?</p>
<p>The posterior uterine wall</p>
<p>What does the zygote need to do before it can implant?</p>
<p>Continue to travel alone the fallopian tube to get where it needs to be to establish the pregnancy</p>
<p>How long is an oocyte viable for?</p>
<p>1 day</p>
<p>How long is sperm viable for?</p>
<p>3 days</p>
<p>What happens immediately after fertilisation?</p>
<p>Sperm is excluded due to a complex chemical reaction</p>
<p>When does cleavage begin?</p>
<p>30 hours after fertilisation</p>
<p>What does cleavage result in?</p>
<p>2 blastomeres of equal size</p>
<p>What is the zona pellucida?</p>
<p>A glycoprotein ‘shell’</p>
<p>What is the result of the presence of the zona pellucida?</p>
<p>The blastomeres are about half the size of the oocyte, as the cell prevents it from expanding</p>
<p>What has happened by day 3 post fertilisation?</p>
<p>The morula has formed</p>
<p>What feature does each cell have at the morula formation stage?</p>
<p>They are totipotent</p>
<p>What is meant by the cells being totipotent?</p>
<p>They have the capacity to become any cell type</p>
<p>What happens in assisted reproductive techniques?</p>
<p>The oocytes are fertilised in vitro, and allowed to divide to the 4- or 8- cell stage. The morula is then transferred into the uterus</p>
<p>What is PGD?</p>
<p>When a cell is removed from the morula and tested for serious heritable conditions prior to the transfer of the embryo into the mother</p>
<p>What is compaction?</p>
<p>Formation of the first cavity</p>
<p>What is the first cavity formed?</p>
<p>The blastocyst</p>
<p>How is the blastocyst formed?</p>
<p>The cells of the morula are secreting tiny amounts of tissue fluid. Together, collect a sufficient amount that it collects, and one clump of cells pushes to one side, giving a space</p>
<p>What does the formation of the blastocyst give?</p>
<p>2 groups of cells</p>
<p>What is the inner group of cells called?</p>
<p>Embryoblast</p>
<p>What is the outer group of cels called?</p>
<p>Trophoblast</p>
<p>What happens to the inner group of cells of the blastocyst?</p>
<p>It goes on to give the embryo</p>
<p>What happens to the outer cells of the blastocyst?</p>
<p>They go on to produce the supporting tissues</p>
<p>What tissues support the embryo during pregnancy?</p>
<p>#NAME?</p>
<p>Why can cells produced by the first divisions after fertilisation become inner or outer cell mass?</p>
<p>Because they are all totipotent, so they have the capacity to become any cell type</p>