From Embryology

Laboratory Attendance

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Laboratory 1

This is an internal Link Cell Division Lecture

This is an external Link SMH

Individual Assesments

Individual Assesment 1


Early zygote.jpg

Laboratory 2


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

Syncytiotrophoblasts secrete the hormone hcG also known as Human Chorionic Gonadotrophin. The secretion of hcG (Human Chorionic Gonadotrophin) via the syncytiotrophoblasts prevents the corpus luteum, the remnants of the ovulated follicle in the ovary from collapsing. The secretion also helps maintain the dicidua which in turn support the ongoing pregnancy.

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

The corpus luteum like stated above in question 1 is actually the remains of the dominant follicle in the ovary and secretes the hormone progesterone to prevent the continuation of the menstrual cycle. The increased levels of progesterone released via the corpus luteum help maintain the endometrial lining of the uterus. If there is a drop in the levels of progesterone this will in turn cause the uterus to shed its lining in a process termed menstruation a part in the menstrual cycle.

Laboratory 3


1. What Carnegie stages occur during week 3 and week 4?

The Carnegie states that occur during Week 3 are:

  • Carnegie Stage 7 which are the stages between day 15 to 17
  • Carnegie Stage 8 which are the stages between day 17 to 19
  • Carnegie Stage 9 which are the stages between day 19 to 21

The Carnegie stages that occur during Week 4 include:

  • Carnegie Stage 10 which are the stages between day 22 to 23
  • Carnegie Stage11 which are the stages between day 23 to 26
  • Carnegie Stage 12 which are the stages between day 26 to 30 and
  • Carnegie Stage 13 which are the stages between day 28 to 32.

2. What is the change in overall embryo size from the beginning of week 3 to the end of week 4?

At the beginning of Week 3 most embryos are approximately 0.4mm Crown to Rump Length (CRL) while when measured at the end of Week 4 the approximate Crown to Rump Length (CRL) of most embryos are three to five millimetres (3mm – 5mm) in size. Thus most embryos grow about 2.6 to 4.6mm between weeks 3 and 4.

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

In the human embryo the cranial or anterior neuropore closes off first during Carnegie Stage 11 to be more precise on day 24. The closure of this neuropore is actually completed within a few hours while the caudal or posterior neuropore closes of during the next Carnegie stage, Carnegie stage 12 at about day 26 of embryo development. The caudal neuropore takes the course of a day to close though compared to the few hours taken by the cranial neuropore.

Laboratory 4


1. Name the vessels that drain into the sinus venous

There are 3 venous input into the sinus venous and these input include, the vitelline veins, the umbilical cord vein and last but not least the common cardinal vein.

2. What is the fate of the vitelline artery and the vitelline vein?

The so called fate of both vitilline arteries and vitelline vein are that the Vitelline Arteries fuse together to become the superior mesenteric artery which is part of the adult gastro-intestinal tract. The vitelline vessels on the other hand eventually contribute to the portal system in the liver of the adult.

3. Name the 4 layers that constitute the placenta barrier

The 4 layers that constitute the placental barrier are:

  • Syncitiotrophoblast
  • Cytotrophoblast
  • Villi Connective Tissue
  • Fetal Capillary Endothelium

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

Umbilical Cord Blood also known as cord blood can actually be harvested at the birth of a child and Haematopoetic stem cells can be collected, typed and stored in so called Cord Blood Banks.

Laboratory 5


1. What is the origin of the gastrointestinal tract smooth muscle?

The origin of the gastrointestinal tract smooth muscle is the splanchic mesoderm which lies adjacent to the endoderm.

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

The buccopharyngeal membrane begins to break down at Carnegie stage 11 and opens the gastrointestinal tract to the amnion.

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

At Carnegie stage 22 the respiratory system develops from the lungs and diaphragm which also includes budding of lungs from the trachea.

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

Premature infants born may not have fully developed type two alveolar cells also known as type 2 Pneumocytes which secrete surfactants necessary to breath properly on their own.

Laboratory 7


1. Briefly; what is a myotube and how is it formed?

A myotube is an multinucleated yet undifferentiated sacromere. Myoblast undergo frequent cell division and then fuse together to form a myotube. The nuclei of the myotube are still located centrally in the muscle fibres.

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

a) Suffered a Spinal Cord Injury

After Spinal Cord Injury the paralysed muscle in the leg would lose its normal mosaic pattern which is composed by the criss crossing of both Type I slow and Type II fast fibres and in time the muscle fibres types in the paralysed leg would predominantly be comprised of consist of type II fast fibres also known as glycotic fibers

b) Took Up Marathon Running

In the leg we expect to see a mixture of both slow and fast twitch fibre types and this is genetically predetermined yet with increase training due to the take up of marathon running the slow twitch fibre types present in the leg will respong strengthing as well as increasing vascular supply and proliferating with expense to the amount of fast twitch myofibers types. Thus in simple terms we will see an increase in slow twitch fibres type and a decrease in fast twitch fiber types.

Peer Review Comments Given By Me

GROUP 1: Ultrasound

The fact that the layout and format of the web page is well formatted makes it easy to follow. It has a really good flow. The tables in the section, especially the table describing the different transducer types made it extremely easy to understand and also the picture sort of make you want to read what the pictures are about. The images that you have on your webpage are really well explained yet as a criticism you could have more pictures for example pictures of the disorders that ultrasounds detect. The page has an extremely scientific feel so you don’t have to change anything there. There are some spelling mistakes like the people above have stated but that shouldn’t be a big problem as you will probably find these in your final check. I really found informative but is sort of thought that maybe if somebody without a background in science would struggle certain parts. Putting it under different sub headings also made this extremely easy to follow as well but all in all I really liked the page. Nice Work!!!

GROUP 2: Chorionic Villi Sampling

This page caught my attention as soon as I saw it and that made me want to read on and thus learn about Chorionic Villi Sampling. A lot of research has gone into this assignment and it’s evident in the information presented as its precise which also helps capture the readers. The amount of research is also evident in the long list of references. The webpage is actually extremely informative covering pretty much every aspect of the pre-natal diagnostic techniques. Your webpage has the most pictures and this helps it stand out as one of the best project pages. I really, really like the formatting and the tables. The images break up the information so you’re never overloaded with the amount of text. The only bit of criticism is spelling but this is extremely minor as you’ll pick up on the spelling mistakes when you go over the page. The language in is the right mixture of scientific language meaning that even people without a scientific background can understand the CVS. Great job guys you really can’t tell that only two people are in this group. It’s extremely good!!! I also really like the first picture you have, gives a page a really good feel to it.

GROUP 3: Amniocentesis

This project is the probably in my opinion the most scientific of all the project pages, but there are point where I felt that if I didn’t have an academic science background I would have got lost. Yet the information presented on the webpage is extremely informative and the structure of the page makes it easy to follow. Referencing for the first few sections is fine but towards the end I find that there are not as many references. The pictures which include the hand drawn pictures are really good and they help break the information into smaller section allowing time to process the information above. Like every other group there are a few spelling mistakes here and there but like I’ve stated on everybody’s pages you will pick them up on your final check. As well I noticed that you don’t really have a proper glossary and I think putting one in would be beneficial but this is just a small suggestion. Apart from that I can’t criticise the assignment. I personally think after reading your assignment the standard of my groups’ assignment should be lifted. You can really tell you have put in a tonne of effort. Well Done Guys!!!

GROUP 5: Fetal Fibronectin

Group 5 the first thing I have to say about your project page that I think will really help you guy out is that you need put more pictures. If I’m not mistaken the hand drawn picture at the very top is the only picture on the whole page. Pictures help captivate the audience and makes your intended audience want to read on to find out or relate the picture to the information present. They also help break up the page and allow the reader some processing time while reading the information of Fetal fibronectin. The Information you have presented is pretty much flawless being the perfect amount of scientific language, by this I mean that your assignment is assessable for pretty much anyone but more importantly the information was informative. The Dot points you have used many of the section also help us understand the project better. Last but not least you have missed out on history of the pre-natal diagnostic technique which Mark Hill said was part of his marking scheme, and after reading what other people have posted on your discussion page I notice that I’m not the only one to make this comment. Apart from that nice work!!!!

GROUP 6: Maternal serum alpha-fetoprotein

To tell you the truth I didn’t find anything wrong with this assignment page. There is a lot of information but that can be expected from an informative web page. Yet the best way to make it look less is just throw some pictures into the mix. I think that your page was the only page that didn’t have any spelling mistakes so good work in that department and keep it up. I sometimes thought in some areas that the language was a bit easy to read and this can be both an advantage or a disadvantage depending on how Mark Hill but as a precaution just add a bit more scientific data. I don’t think it will hurt. I felt that in some place maybe a table would better suit the information presented but that just me. I also found the introduction had things that could be covered in sections below but I’m not sure if that was intentionally done. The best way to reduce the amount of words used to describe is to dot point or tabulate coming back to my old point but apart from that I found the assignment very informative and interesting which really isn’t easy when you have all those word, most people would have rambled on. So hats off to you there. The flow of the page is disrupted but you can fix that up by just moving bits and pieces around the page seeing where it fits best. A really good assignment. Well Done Guys!!!!

Laboratory 10


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

The development of the thyroid gland is affected by low dietary iodine

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

The affects of iodine deficiency or in other words low dietary iodine affect non-endocrine system development by causing problems at and before birth such as miscarriage and still birth and mental retardation. Children that have an iodine deficiency can have a stunted growth, low body weight, low body temperature, poor muscle tone and are usually lethargic. They may also not be able of normal speech, hearing and movement due to this iodine deficiency.

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

Many of the endocrine organs such as the thyroid gland, pituitary gland, and the pancreas begin their function approximately in Week 10 of development.

Laboratory 12


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

Fetal Length changes the most during the second trimester of pregnancy which are weeks 13 to 24 while the greatest change in fetal weight occurs during the final trimester also known as the third trimester, which are weeks 25 to 40 of pregnancy.

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

Barker collected low birth weight data in the early 1900’s in the south east of England which he then compared with these same babies later health outcomes and it was this statistical analysis that lead to the theory that postnatal health is linked with prenatal development. Therefore the theory was originally called the “Barker Hypothesis” but recently the theory has been renamed as the “fetal origins hypothesis” or “programming hypothesis”

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

The main hormone that both initiates and maintains labour during birth is Oxytocin, which is a 8aa peptide hormone which is secreted by the maternal posterior pituitary. Another group of hormone that are involved in the initiation and maintenance of labour are the Prostaglandins such as PGF2 Alpha and these are synthesised by the placenta.