Chapter 3 - Development Flashcards
Where does fertilization usually occur?
In the ampulla of the fallopian tube.
What is the difference between Determinative Cleavage and Indeterminate Cleavage?
Determinate refers to cell division that results in cells having definite lineages. Indeterminate refers to cell division that results in cells that can differentiate into any cell type (or a whole organism).
From zygote to gastrula, what are the various stages of development? (5)
- Zygote
- 2-,4-,8-, and 16-cell embryo
- Morula
- Blastula (blastocyst)
- Gastrula
What’s the difference between Fraternal (dizygotic) twins and Identical (monozygotic) twins?
Fraternal twins result from the fertilization of two eggs by two different sperm. Identical twins result from a zygote splitting in two.
During which stage of development does implantation occur?
Blastula (blastocyst) stage. The blastula implants in the endometrial lining and forms the placenta.
What is Gastrulation?
The generation of three distinct cell layers: the primary germ layers.
What are the three primary germ layers?
- Ectoderm
- Mesoderm
- Endoderm
What does the Ectoderm account for?
It becomes the epidermis, hair, nails, and the epithelia of the nose, mouth, and anal canal, as well as the nervous system (including adrenal medulla).
What does the Mesoderm account for?
Becomes much of the musculoskeletal, circulatory, and excretory systems. Also gives rise to the gonads, tissue layers of the digestive and respiratory tracts, and the adrenal cortex.
What does the Endoderm account for?
Becomes much of the epithelial linings of the respiratory and digestive tracts, and parts of the pancreas, thyroid, bladder, and distal urinary tracts.
What is Induction and how does it influence development?
Induction is the process by which nearby cells influence the differentiation of adjacent cells. This ensures proper spatial location and orientation of cells that share a function or have complementary functions.
What tissues do neural crest cells develop into?
Neural crest cells become the peripheral nervous system (including the sensory ganglia, autonomic ganglia, adrenal medulla, and Shwann cells) as well as specific cell types in other tissues (such as calcitonin-producing cells of the thyroid, melanocytes in the skin, and others).
What is Neurulation?
Development of the Nervous System. Begins after the formation of the three germ layers.
What are Teratogens?
Substances that interfere with development, causing defects. Examples include, alcohol, some perscription drugs, viruses, environmental chemicals etc.
What is Determination?
The commitment of a cell to a particular lineage. This may be accomplished by uneven segregation of cellular material during Mitosis or with Morphogens, which promote development down a specific cell line.
