From Embryology

Attendance in Labs

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Lab 1 Questions


  1. Make an internal link: Cell Division & Fertilization Lecture
  2. Make an external link: SMH
  3. Rename a Link: First Stage of Development
  4. Add a picture and add a subheading:


Zygote picture:

Early zygote.jpg

Lab 2 Questions

  • Assignment information:

Journal resources for assignment: Public Library of Science | Biomed Central | PNAS | more reference information

  • Search pubmed:

Search Bookshelf Gastrulation Searches books

Search Pubmed Now: Gastrulation Searches references in articles

  • What factor do the syncytiotrophoblast cells secrete to support the ongoing pregnancy?

Syncytiotrophoblasts secrete the hormone hcG, human chorionic gonadotrophin, as well as the hormone progesterone. HCG prevents the collapse of the corpus luteum and progesterone maintains the thickened endometrium of the uterine wall. When fertilization does not occur the corpus luteum degenerates as it is not needed, however if fertilization does occur the syncytiotrophoblasts secrete hCG as the corpus luteum is needed to produce progesterone until the growing embryo can produce its own hormones.

  • What does the corpus luteum secrete to prevent continuation of the menstrual cycle?

The corpus luteum which is the remnants of the ovulated follicle plays a role in secreting progesterone. Increased progesterone levels are needed during the stages of embryo development as it maintains the endometrium, the lining of the uterus, making sure it stays highly vascularised to supply the growing embryo with nutrients in a placental function. Progesterone also prevents contractions of the uterus to make sure menstrual bleeding does not occur and the embryo does not get secreted from the uterine wall with the secretory layer. The body needs the corpus luteum to produce progesterone until the growing embryo is mature enough to produce its own hormones.

Lab 3 Questions

  • What Carnegie stages occur during week 3 and week 4?

During week 3 carnegie stages 7, 8 and 9 occur (days through 15 to 21). During week 4 carnegie stages 10, 11, 12 and 13 (days 22 through to 30).

  • What is the change in overall embryo size form the beginning of week 3 to the end of week 4?

The embryo changes from 0.4mm to 3-5 mm from week 3 to 4.

  • Approximately when do the cranial (anterior) and caudal (posterior) neuropores close in the human embryo?

The cranial neuropore closes on day 24 and the caudal neuropore closes on day 26.

Lab 4 Questions

  • Name the vessels that drain into the sinus venosus?

The vessels that drain into the sinus venosus are the vitelline veins, umbilical veins, and cardinal veins.

  • What is the fate of the vitelline artery and vitelline vein?

The vitelline vessels eventually contribute to the portal system of the liver of the adult.

  • Name the 4 layers that constitute the placental barrier?

The 4 layers are the amnion, the chorionic plate, the intervillous space and the basal plate.

  • What stem cells are found in abundance, and may be harvested from the placenta for therapeutic uses?

Hematopoietic stem cells.

Lab 5 Questions

  • What is the origin of the gastrointestinal tract smooth muscle?

Splanchnic mesoderm.

  • At what Carnegie stage does the buccopharyngeal membrane begin to break down?

Carnegie stage 11.

  • Identify the lung developmental stage in late embryonic to early fetal period.

Embryonic development of the lungs begins in stage 14 (branching of bronchial tree). The development of the functional alveoli begins from stage 22 until late fetal.

  • In premature infant birth, which respiratory cell type may not have fully developed?

Alveolar cell type 2 which secrete surfactant.

Lab 7 Questions

  • Briefly; what is a myotube and how is it formed?

A myotube is a developing muscle fibre. They form as the myoblasts fuse forming multi nucleated myotubes.

  • What changes would I expect to see in the muscle fibre types in my legs if I:

a) Suffered a spinal cord injury

Muscle atrophy.

b) Took up marathon running

Some fast type muscle fibres changing to slow type muscle fibres.

Lab 10 Questions

  • Development of which endocrine organ is affected by low dietary iodine?

The thyroid gland is affected.

  • What are the affects of this deficiency on other non-endocrine system development?

Iodine deficiency causes neurological defects known as cretinism, mental retardation, brain damage and swelling of the thyroid gland known as goiter.

  • At approximately what week in development do many endocrine organs appear to begin their function?

Approximately week 10.

Lab 12 Questions

  • During which trimester does fetal length change the most and when does fetal weight change the most?

Fetal length is constant throughout all three trimesters, fetal weight increases most during the last trimester.

  • What is the name of the theory that links postnatal health with prenatal development?

Fetal origins hypothesis.

  • Which hormone initiates and maintains labour during birth and where does it come from?

Oxytocin which is secreted from the posterior pituitary.

Peer Assessment

Group 1: Ultrasound

Group 1, your project is very detailed and there seems to be lots of research gone into it, also evident by your reference list. Your procedure section is very detailed and scientific, it maybe could be broken into more point form to make it easier to read. Your detail in abnormalities shows extensive research, the ultrasound specific heart defects is particularly interesting as it is a unique set of disorders that can be detected compared to the other techniques. Your current research is really interesting as well and easier to understand than some of the other projects. Overall, great job.

What could be improved: More detail in the history section, the time line gives a good overview but maybe some more detail on the key scientists and research leading to the procedure, besides a link to another page. Maybe some more pictures other than the ultrasound ones, like of disorders, or of the actual ultrasound machines would be good to break up the page.

Group 2: Chorionic Villus Sampling

Group 2, your project is looking great, the first thing i noticed when reading it is that there is lots of detail which shows a great depth of research has gone into it, which is supported by your reference list. Another thing is the amount of pictures which support the information and break it up to make it easier to take in so much information at once. The disorders table provides great detail and makes it interesting with the pictures.

What could be improved: You could put the advantages/disadvantages into a table form to make it even easier to understand. The reasons to use this technique could be slotted into the procedure section instead of the introduction maybe as it shows who is eligible for the procedure. The current research section could be put more into point form to make it more inviting to read. But overall really great project.

Group 4: Percutaneous Umbilical Cord Blood Sampling

Group 4, the overall layout of your page is great, it makes it easy to understand rather than having lots of big paragraphs. The table comparing the 3 techniques is a great idea as it puts the procedure in terms of all the others, I reckon we could all put a comparison like that on our pages. The history section is really good as well, the time line gives a good overview and the detail of the scientists underneath gives a scientific depth to the section. The procedure is also really well set out and easy to understand, if those are hand drawn diagrams they're amazing! Overall i think you've done a great job with the project!

What could be improved: More detail in the current research aspect, the glossary could be added to a bit, and maybe a couple more pictures to add more interest to the page.

Group 5: Fetal Fibronectin

Group 5, the set out of your page is really good, its broken up into sections and there's lots of point form throughout which makes it really clear and easy to understand, except for current research. What could be improved: More pictures would help break it up and make it more interesting, maybe a picture of the actual procedure would be good. Some more detail could be added to give it a more scientific aspect like for example in the procedure section, and maybe a section on the historic background, I think thats part of the marking criteria. Overall i think you've done a great job but just maybe add some more detail to give it a more scientific feel.

Group Project 6: Maternal serum alpha-fetoprotein

Group 6, I think the structure of your page is great, there's enough subheadings to break it into clear sections, but maybe more point form could be used to break it up a little. The information is very detailed so it shows lots of research but its written in a clear enough way to be understandable, and it has a good scientific feel. The student drawn diagrams, especially the one of the analysis process, is great and helps to explain the information really well. What would improve this project: Maybe some more references, and you could also put in a section of the historic background of the procedure with some of the information that's in the introduction.