A cytochemical analysis was undertaken of C cells of thyroid
glands obtained from sixteen young oogs and five human s t ill - b o r n
neonates.
Tissues were fixed in selective liquid fixatives (N e lly 's , Carnoy s,
glutaraldehyde-picric-acetic acid, glutaraldehyde-potassium dichromatesodium
sulphate and formol-saline) or fixed in formalin vapour a f t e r
freeze drying. Cryostat sections and some of the above fixatives were
used for enzyme demonstration.
Simple and conjugated proteins in the cytoplasm of canine C cells
were studied by numerous cytochemical reactions. Acetylatiun, methylation,
benzoylation, nitrosation, acid hydrolysis and aldehyde blockade as well
as enzyme hydrolysis were employed to evaluate the aldehyde fuchsin,
colloidal iron, toluidine blue and periodic acid-Schiff staining reactions
in canine C cells.
I have confirmed that the cytoplasm of canine C cells contains an
abundance of acidic protein groups which are due to side-chain carboxyls.
Mild acid hydrolysis, amongst other reactions, may result in peptide
hydrolysis at the aspartyl group, which hydrolysis contributes to the
anionic charge in the C cell cytoplasm. Basic proteins are not readily
stained in the canine C c e l l . Bisulphide groups are numerous and their
oxidation adds to the negative charge of the C cell cytoplasm.
I found that the positive aldehyde fuchsin and colloidal iron
reactions are not attributa ole to mucosubstances such as sulphomucms,
sialomucins or acidic mucopolysaccharides, but seem to be imparted by an acidic protein unconjugated to polysaccharide. A positive aldehyde
fuchsin reaction probably depends on both disulphidc and carboxyl
groups within C c e lls . A positive colloidal iron reaction in canine C
cells requires the presence of carboxyl groups but an increased number of
these groups does not enhance the staining reaction.
The conditions required generally for s ilv e r binding and more
specifically for the Grimelius s ilv e r impregnation in canine C cells
were evaluated by oxidation and various other cytochemical procecures.
I found that the argyrophilia of thyroid C colls depends upon an
exogenous reducing agent and upon pH, optimal impregnation occurring at
a s lig h tly acid pH. Oxidation preceding s ilv e r impregnation by the
Grimelius method, reduces the a f f i n i t y of structures in the cell for
s ilv e r n itr a te . Indirect evidence supports the view that argyrophilia
in the C cells depends upon disulphide groups. I t is suggested that
s ilv e r nitrate and disulphide groups react in C cells to form silv e r
nercaptide which produces the argyrophilia.
The presence of C cel s was demonstrated in human neonates by means
of cytochemical methods known to demonstrate C cells in dogs. C cells
were found predominantly in the posterior region and upper pole of both
lobes where they were found scattered in clusters of six to eight cells
per high power f i e l d Two morphological forms of normal human C cells
were observed - an ovoid cell and one with cytoplasmic processes.
By demonstrating oxidative enzymes and masked metachromasia, three
categories of e p ith e lia l cells have been shown in the neonatal thyroid
gland : A ( f o l l i c u i a r ) , C and AC (intermediate) c e lls . The l a t t e r
may be homologous with the oxyphil cells observed in normal and
pathological adult thyroid glands.
The c lin ic a l applications in which I have useo the results of the
above studies are outlined in the la s t section of the dissertation.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/19222 |
| Date | January 2015 |
| Creators | Roediger, W E W |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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