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==Lab 3==
==Lab 3==
===Questions===
    1. 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).
    2. What is the change in overall embryo size form the beginning of week 3 to the end of week 4?

Revision as of 10:56, 16 August 2010

Attendance in Labs

--z3292208 23:43, 28 July 2010 (UTC)

--z3292208 23:15, 4 August 2010 (UTC)

--z3292208 22:57, 11 August 2010 (UTC)


Lab 1

Internal Link: Cell Division & Fertilization Lecture

External Link: SMH

Renamed Link: First Stage of Development

Picture

Zygote picture:

Early zygote.jpg


Lab 2

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


Questions

    1. 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.

    2. 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

    1. 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).

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