Term
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Definition
| the study of the development of single individual |
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Term
| What is the prenatal period? What periods does it consist of? |
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Definition
"before birth"
-embryonic
-fetal |
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Term
| What is the embryonic period? |
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Definition
first 8 weeks
-orgnas form from three embryonic germ tissues; emergence of the basic body plan. |
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Term
| What is the fetal period? |
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Definition
Remaining 30-32 weeks
-tissues/organs grow in size and complexity |
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Term
| What is week 1 of the embryonic period? |
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Definition
zygote to blastocyst:
-Zygote moves toward the uterus; fertilization in lateral third of uterine tube
-Blastomeres- daughter cells formed from zygote
-Morula- cluster of 16-32 blastomeres
-Blastocyst- fluid filled structure, about 60 cells |
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Term
| What makes up a blastocyst? |
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Definition
inner cell mass- cluster of cells (future fetus)
Trophoblast- outer layer (contributes to placenta) |
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Term
| Week 2 of the Embryonic period? |
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Definition
Bilaminar Embryonic disk, inner cell mass divided into two sheets.
Amniotic sac
yolk sac |
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Term
| What are the two sheets of the Bilaminar disc? |
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Definition
| 1. Epiblast and Hypo blast |
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Term
| What is the Amniotic Sac? |
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Definition
formed by an extension of epiblast
-forms the amnion and amniotic sac cavity that is filled with amniotic fluid |
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Term
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Definition
| formed by an extension of hypoblast. |
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Term
| Is the yolk significant to humans? What is formed by the yolk sac? |
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Definition
| no. A small portion of the digestive tube forms from part of yolk sac. |
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Term
| What do tissues around yolk sac give rise to? |
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Definition
| earliest cells and blood vessels |
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Term
| Week 3 of the Embryonic Period Includes: |
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Definition
The three-layered embryo.
-Primitve Streak
-Notochord
-Neurulation
-Mesoderm Begins to differentiate |
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Term
| What is the primitive streak? |
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Definition
| raised grooves on the dorsal surface of the epiblast; gastrulation is a process of invagination of epiblast cells |
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Term
| What does the primitive streak produce? |
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Definition
| 3 layers of cells which will form all tissues in the body. |
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Term
| What are the 3 layers of cells? |
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Definition
Endoderm- formed from migrating cells that replace the hypoblast
Mesoderm- formed between epiblast and endoderm
Ectoderm- formed from epiblast cells that stay on dorsal surface. |
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Term
| What is the notochord formed from? |
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Definition
| Primitive node- a swelling at one end of primitive streak; cells that mvoe through node become notochord |
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Term
| What does the Notochord define? |
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Definition
Body axis- acts as a scaffold for the furture vertebral column.
-one of the first structures to form. |
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Term
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Definition
| ectoderm starts forming brain and spinal cord. |
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Term
| Ectoderm in the dorsal midline thickens to create: |
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Definition
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Term
| Ectoderm folds inward to create: |
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Definition
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Term
| A hollow tube pinches off into the body to form: |
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Definition
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Term
| Cranial part of the neural tube becomes: |
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Definition
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Term
| What is the neural crest? |
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Definition
| cells adjacent to neural plate; pulled along with the neural tube. Forms sensory nerve cells, ganglia, and melanocytes. |
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Term
| What happens as the mesoderm begins to differentiate? |
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Definition
somites- our first body segments (from paraxial mesoderm, adjacent to notochord)
intermediate mesoderm begins as a continuous strip of tissue just lateral to paraxial mesoderm.
Lateral Plate (mesoderm)- most lateral part of mesoderm splits into 2 halves. |
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Term
| What becomes the serous body cavities? |
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Definition
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Term
| What is apposed to the ectoderm? |
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Definition
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Term
| What is apposed to the endoderm? |
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Definition
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Term
| What happens in week 4 of the embryonic period? |
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Definition
The body takes shape.
-folding of embryo laterally and at the head and tail forms the primitive gut. |
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Term
| At day 24 what is the shape? |
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Definition
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Term
| What derives from the ectoderm in week 4? |
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Definition
| ectoderm- forms brain, spinal cord, and epidermis |
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Term
| What derives from the endoderm? |
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Definition
| Forms inner epithelial lining of the gut tube and respiratory tubes, digestive organs, including liver and pancreas and urinary bladder. |
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Term
| What does the notochord give rise to in week 4? |
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Definition
| nucleus pulposus within intervertebral discs |
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Term
| What does the mesoderm give rise to in week 4? |
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Definition
| forms muscle bone dermis and connective tissues |
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Term
| What does the Somites give rise to in week 4? |
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Definition
| divide into sclerotome (vertebrae) dermatomme (dermis of dorsal body) and myotome (trubk and limb muscles) |
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Term
| What does the intermediate mesoderm give rise to in week 4? |
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Definition
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Term
| What does the Lateral Mesoderm give rise to in week 4? |
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Definition
| -splanchnic mesoderm and somatic mesoderm |
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Term
| splanchnic mesoderm forms: |
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Definition
| musculature, connective tissues, and serosa of the digestive and respiratory structures. Forms heart and most blood vessels |
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Term
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Definition
| dermis of skin, bones and ligaments |
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Term
| During weeks 5-8 what happens? |
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Definition
limb buds form
embryo first looks recognizably hums
head is disproportionately large
all major organs are in place |
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Term
| Rapid growth and maturation occurs in: |
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Definition
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Term
| During the first half of the fetal period cells are: |
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Definition
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Term
| Normal births occur # weeks after conception? |
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Definition
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Term
| A premature birth is one that occurs before: |
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Definition
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