User:Z3252635

Laboratory Attendance

--z3252635 23:44, 28 July 2010 (UTC)

--z3252635 23:16, 4 August 2010 (UTC)

--z3252635 23:18, 11 August 2010 (UTC)

--z3252625 23:10, 18 August 2010 (UTC)

Laboratory 1

This is an internal Link Cell Division Lecture

This is an external Link SMH

Individual Assesments

Individual Assesment 1

Picture

Laboratory 2

Questions:

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

Questions:

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.