Questions and Answers
What are the three primary germ layers during organogenesis?
Ectoderm, Endoderm, Mesoderm
Which class of cells in animals are responsible for reproduction and the propagation of the species?
Epithelial tissue regulates exchange between the body and the external environment. True or False?
True
Epithelial tissue consists of cells fitted tightly together to form a continuous layer of cells. One surface is exposed while the other attaches to underlying tissue by a noncellular __________ membrane.
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Match the following cell types with their respective animal tissues:
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Study Notes
Germ Layers
- Germ layers are the three primary layers of cells in an embryo from which all tissues and organs develop
- The three germ layers are: Ectoderm, Endoderm, and Mesoderm
Formation of Germ Layers
- Gametogenesis: production of gametes (sperm and ova) in testes and ovaries
- Fertilization: transmission of genetic material from parents
- Cleavage: rapid mitotic cell divisions of zygote to form blastula
- Blastulation: formation of blastula
- Gastrulation: rearrangement of cells into three germ layers (ectoderm, endoderm, and mesoderm)
- Organogenesis: formation of organs
Ectoderm
- Outermost layer
- Gives rise to: central nervous system, lens of the eye, cranial and sensory ganglia, nerves, pigment cells, epidermis, hair, and mammary glands
Endoderm
- Innermost layer
- Gives rise to: lining of digestive system and other internal organs
Mesoderm
- Middle layer
- Gives rise to: muscles, bones, blood vessels, and connective tissue
- Formation of coelom (body cavity)
Comparison of Germ Layers
- Sponges: single germ layer
- Diploblastic animals (Cnidaria and Ctenophores): two germ layers (endoderm and ectoderm)
- Triploblastic animals: three germ layers (ectoderm, endoderm, and mesoderm)
Histology and Histogenesis
- Histology: study of microscopic structures of tissues
- Histogenesis: formation of different tissues from undifferentiated cells
Types of Animal Tissues
- Epithelial tissue: forms continuous layers, covers body surfaces, and lines cavities
- Connective tissue: supports and connects other tissues
- Muscle tissue: contracts to move body parts
- Nervous tissue: transmits and processes information
Epithelial Tissues
- Functions: protection, absorption, secretion, and sensation
- Examples: epidermis, digestive tract, glands, and sensory receptors
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Description
This quiz covers the formation and function of primordial germ layers, types of epithelial tissues, and the differences between somatic and germ cells in animals.
