Related Experiment Videos
Actin-like filaments in the myoid cell of the testis
Abstract:
Microfilaments in the myoid cells of the peritubular tissue in the mouse, swine and human testis bind heavy meromyosin (HMM) and form arrowhead complexes. The periodicity of the arrowhead complexes is about 35 nm. Individual filaments show arrowheads that point in the same direction. Opposing polarity of the HMM-bound filaments is also observed. The microfilaments do not bind HMM in the presence of 10 mM ATP. After treatment with the contraction medium of Hoffmann-Berling, the filaments appear to be undulated. These observations indicate that the microfilaments in the myoid cell are actin-like in nature. A small number of thicker filaments (about 10 nm in diameter) which do not bind HMM is also observed in the cell. Microfibrils which have been reported around the human myoid cell are also found in the swine.
Insights
Testicular myoid cells contain actin-like microfilaments that bind heavy meromyosin (HMM), forming characteristic arrowhead complexes. These findings reveal the contractile nature of these filaments in mouse, swine, and human testes.
Area of Science:
- Cell Biology
- Reproductive Biology
- Biochemistry
Background:
- Myoid cells in the peritubular tissue of the testis play a crucial role in testicular function.
- The precise composition and nature of the cytoskeletal elements within these myoid cells require further elucidation.
Purpose of the Study:
- To investigate the molecular nature of microfilaments present in the myoid cells of the testis.
- To characterize the interaction of these microfilaments with heavy meromyosin (HMM) and their structural organization.
Main Methods:
- Immunofluorescence labeling of testicular tissue with heavy meromyosin (HMM).
- Observation of microfilament structures using electron microscopy.
- Assessment of filament behavior after treatment with contraction medium.
Main Results:
- Microfilaments in mouse, swine, and human myoid cells bind HMM, forming distinct arrowhead complexes with a periodicity of approximately 35 nm.
- Filaments exhibit uniform polarity within complexes, with opposing polarities observed between adjacent filaments.
- HMM binding is inhibited by ATP, and filaments appear undulated after contraction medium treatment, suggesting actin-like properties.
- Thicker, HMM-non-binding filaments (approx. 10 nm diameter) and microfibrils were also observed.
Conclusions:
- The microfilaments in testicular myoid cells are actin-like, possessing contractile properties.
- These actin-based structures are conserved across species (mouse, swine, human) and contribute to myoid cell function.