Today in class we reviewed the menstrual cycle, learned about the development of the embryo, and watched a video on it.
When estrogen levels get low, the hypothalamus signals the pituitary gland to release FSH (Follicle Stimulating Hormone) and LH (Leutinizing Hormone). FSH stimulates the ovaries to produce more estrogen, which builds up the lining of the uterus, while LH controls the formation of the corpus luteum and signals for ovulation to occur.
Fertilization occurs in the oviduct. A fertilized egg is called a zygote. Cell division will begin; the embryo is just one cell, the morula is a solid ball of cells, then the blasocyst which is a hollow ball of cells. The blasocyst takes a week to implant in the uterine lining (implantation). After this, differentiation occurs and the cells specialize. This then leads to gastrulation.
Gastrulation is the formation of 3 embryonic development germ layers. Endoderm makes up the lining of the digestive, reproductive, and respiratory system. Mesoderm makes up the muscles, blood, and bones. Ectoderm makes up the skin and nervous system.
In the video, we saw how the embryo turns into the morula and then into the blasocyst. We saw how the blasocyst implants in the uterine lining and the development of the baby in the uterus.
Our homework for today is to post a muddiest point by tonight and comment on one tomorrow. We also have a test on this unit this Thursday.
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