Collagen biogenesis and assembly into fibrils as shown by ultrastructural and 3H-proline radioautographic studies on the fibroblasts of the rat food pad
To examine whether collagen is assembled into fibrils within or outside fibroblasts, the connective tissue of the rat foot pad was investigated by electron microscopy and by radioautography at times varying from 4 min to 3 days after an intravenous injection of 3H-proline. The fibroblasts of the rat food pad are long polarized cells with the nucleus at one end, the Golgi apparatus in the center, and a region with long processes at the other end. This region contains secretory granules and is considered to be the secretory pole of the cell. In the Golgi apparatus the stacks of saccules are separated from rough endoplasmic reticulum (rER) by groups of ''intermediate vesicles'' including similarly structured tubules which may be over 300 nm long and are referred to as ''intermediate tubules.'' The Golgi saccules exhibit distended portions which differ at the various levels of the stack. Finally, the fibroblasts are associated with two types of collagen fibrils: extracellular ones arranged into large groups between the cells and intracellular ones located within long intracytoplasmic channels. Quantitative radioautography after 3H-proline injection reveals that the number of silver grains per unit area reaches a peak over the rER at 4-10 min, Golgi apparatus at 40 min, secretory granules at 60 min, and extracellular collagen fibrils at 3 h. At no time are intracellular collagen fibrils labeled. Qualitative observations further indicate that spherical Golgi distentions are mainly labeled at 40 min, and cylindrical distentions, at 60 min. In addition, from 20 min to 3 hr, some lysosomal elements are labeled.
- Research Organization:
- McGill Univ., Montreal, Quebec, Canada
- OSTI ID:
- 6832930
- Journal Information:
- Am. J. Anat.; (United States), Vol. 168:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COLLAGEN
BIOSYNTHESIS
CONNECTIVE TISSUE
TRACER TECHNIQUES
FIBROBLASTS
BIOCHEMICAL REACTION KINETICS
AUTORADIOGRAPHY
CONNECTIVE TISSUE CELLS
CYTOLOGY
LABELLED COMPOUNDS
RATS
TRITIUM
ANIMAL CELLS
ANIMAL TISSUES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGY
BODY
HYDROGEN ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIGHT NUCLEI
MAMMALS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RODENTS
SCLEROPROTEINS
SOMATIC CELLS
SYNTHESIS
TISSUES
VERTEBRATES
YEARS LIVING RADIOISOTOPES
550901* - Pathology- Tracer Techniques