Anatomy Exam One: Developmental Stage

Why is it important to study embryology?
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Why is it important to study embryology?
It advances knowledge concerning the beginnings of human life. It helps us to understand the causes of congenital anomalies, and possibly correct them. It helps us to more fully understand adult anatomy.
What are the corona radiata and zona pellucida?
Corona radiate is the portion of the egg which the sperm penetrates first.
Zona pellucida is another portion of the egg which the sperm penetrates second.
What are the three phases of fertilization?
Corona radiate, zona pellucida, Fusion of sperm and oocyte plasma membranes: zygote
What events take place in each of the first three weeks of human development?
Week one: Fertilization, cleavage, blastocyst formation, and early implantation
Week two: Implantation is concluded, formation of the Bilaminar Embryo, and the formation of the Extraembryonic Membranes
Week three: Gastrulation, Neural Plate Formation, and Derivatives of the Germ Layers
What is a morula?
Morula is formed with the cleavage and is a solid ball of cells resulting from division of a fertilized ovum, and from which a blastula is formed.
Draw and label a blastocyst. When does the blastocyst form?
A blastocyst is formed at the end of the week from the morula and enters the uterus
Briefly describe the process of implantation. When does it begin? When does it conclude?
Implantation begins during the first week when the blastocyst superficially attaches to the endometrium. and is concluded during the second week when the blastocyst is entirely surrounded by endometrium by ~day 10 or 12
Name the extraembryonic membranes that form during the second week.
The amniotic cavity (yolk sac) and chorion
Describe the process of gastrulation and note what structure marks its beginning. When does it occur?
During gastrulation cell movements occur which reorganizes the epiblast into three germ layers: the ectoderm, mesoderm and endoderm.
The first evidence of gastrulation is the formation of the primitive streak
What does the neural plate form? This structure then develops into what two important structures in the human body?
The neural plate is the beginning of the formation of the nervous system. The neural plate will form a neural tube, which then forms the brain and spinal cord.
Name the three primary germ layers. What do each of them become?Ectoderm, mesoderm, and endoderm Ectoderm: Forms skin and nerves. Mesoderm: Forms muscles, connective tissue, blood cells, heart, the urogenital system, and parts of most of the internal organs. Endoderm: Forms the liver, pancreas and epithelial lining of the respiratory and digestive tubes.When does the embryonic period occur?The embryonic period stretches from fertilization to the end of the eighth week. During the embryonic period the major organ systems develop and the embryo becomes recognizable as a human being.When does the fetal period occur?The fetal period extends from the ninth week of pregnancy to birth. Development during the fetal period is primarily concerned with rapid growth of the body and differentiation of tissues and organs that started to develop during the embryonic period.