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Ultrastructure of mucocysts and pellicle of Tetrahymena pyriformis
Abstract:
Tetrahymena pyriformis GL was fixed with glutaraldehyde and/or OsO(4) for a study of cytoplasmic ultrastructure. Many small vacuoles 0.05 to 0.5 micro in diameter were found to contain each a dense particle enveloped by a limiting membrane. This membrane is continuous with the membrane of the vacuole. The particles are irregular in shape and size, but similar to the mucocysts in the appearance of the matrix. It is suggested that they are the first morphologically distinguishable stages in the development of mucocysts. In the course of this development, amorphous material becomes crystalline with a longitudinal period of 150 A and a lateral period of 100 A. The mature mucocysts are rather uniform in size and have a spheroidal shape. During discharge, the crystalline pattern disappears and the mucocysts assume a spherical configuration. The inner limiting membrane of a mucocyst seems to disintegrate during the process of discharge while the outer membrane becomes continuous with the outermost pellicular membrane; the inner pellicular membrane is continuous with the cytoplasmic membrane. Rows of few to 15 or more microtubules were found either between the cytoplasmic membrane and the ectoplasmic layer (longitudinal fibrils) or underneath the ectoplasmic layer (transverse fibrils). The outer and inner pellicular membranes are uniformly spaced and connected by "cross-bridges." Details of these structures are described.
Insights
This study reveals early developmental stages of mucocysts in Tetrahymena pyriformis GL, identifying dense particles within vacuoles as precursors. These particles develop crystalline structures before forming mature mucocysts.
Area of Science:
- Cell Biology
- Protozoology
- Ultrastructural studies
Background:
- Tetrahymena pyriformis GL is a ciliated protozoan widely used in biological research.
- Understanding cellular structures and their development is crucial for cell biology.
Purpose of the Study:
- To investigate the cytoplasmic ultrastructure of Tetrahymena pyriformis GL.
- To identify and characterize early developmental stages of mucocysts.
Main Methods:
- Fixation of Tetrahymena pyriformis GL using glutaraldehyde and/or OsO(4).
- Transmission electron microscopy for ultrastructural analysis.
Main Results:
- Identified small vacuoles containing dense particles as potential early mucocyst stages.
- Observed the development of crystalline structures within these particles.
- Described the ultrastructure of mature mucocysts and their discharge process.
- Detailed the arrangement of microtubules (fibrils) and pellicular membranes.
Conclusions:
- The dense particles within vacuoles represent the initial morphologically distinguishable stages of mucocyst development.
- The study provides insights into the dynamic changes during mucocyst formation, maturation, and discharge.
- Detailed description of pellicular structures and associated microtubules.