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1. Culture media and conditions were developed to maximize the sexual development of <I>Nannizzia incurvata</I> using liquid culture and solid media, modified Sabouraud's 1/6 salts + hair medium being the most suitable. 2. Strong evidence for the existence of two sex hormones which regulate sexual differentiation was found. It is proposed that these hormones are named (+)-factor (which is produced by (+)-cells and induce a sexual response in (-)-cells) and (-)-factor (which is produced by (-)-cells and induce a sexual response in (+)-cells). 3. Addition of active extracts of concentrated mated culture filtrates caused a switch from asexual to sexual development and the formation of the characteristic sexual cleistothecia. The hormones present are probably extracellular, as mycelial extracts do not cause this response. 4. Further evidence for the existence of these sex hormones was achieved by separation of compatible strains by a semi-permeable membrane, cellophane, which allowed diffusion of the hormones through the medium yet prevented physical, hyphal interactions between the two strains. Sexual morphogenesis occurred in both strains. 5. Both (+)-factor and (-)-factor were shown to be non-volatile by further experiments separating colonies with cellophane membranes. 6. (-)-Factor was solvent extractable using diethyl ether or ethyl acetate, while (+)-factor remained in the aqueous phase. Thus, (-)-factor is more hydrophobic yet less polar and (+)-factor is more hydrophilic yet more polar.

Call number: LD2668 .T4 1951 M4 / Master of Science

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.

by Poon Yim-chu Daisy. / Bibliography: leaves 128-148 / Thesis (M.Phil.) -- Chinese University of Hong Kong, 1983

by Wai-kit Hon. / Bibliography: leaves 129-140 / Thesis (M.Ph.)--Chinese University of Hong Kong, 1985

by Lam Kang Yau. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1992. / Includes bibliographical references (leaves 127-143). / Acknowledgements --- p.iii / Abstract --- p.iv / List of abbreviations --- p.vi / Introduction --- p.1 / Literature review / Chapter A. --- Historical background --- p.6 / Chapter B. --- Histology on the epidermis of squamate reptile --- p.8 / Chapter C. --- The effects of thyroid hormone on the integument in the vertebrate --- p.13 / Chapter D. --- Extrathyroidal conversion of T4 to T3 --- p.18 / Experiment 1. The study of epidermal cellular changes and the effect of Tx on the sloughing cycle of Elaphe taeniura / Introduction --- p.21 / Materials and methods --- p.22 / Results --- p.26 / Discussion --- p.34 / Experiment 2. To study the extrathyroidal conversion of T4 to T3 (5'-D activities) of Elaphe taeniura / Introduction --- p.47 / Materials and methods --- p.48 / Results --- p.52 / Discussion --- p.54 / Experiment 3. The study of the effects of T3 and Tx on the sloughing cycle of Elaphe taeniura and in vitro 5'-deiodinating activities / Introduction --- p.56 / Materials and methods --- p.58 / Resul ts --- p.63 / Discussion --- p.81 / Experiment 4. The study of plasma T3 and T4 levels during the sloughing cycle of Elaphe taeniura / Introduction --- p.111 / Materials and methods --- p.112 / Results --- p.114 / Discussion --- p.115 / General discussion --- p.120 / Summary and conclusions --- p.125 / References --- p.127

Thesis (M. Phil.)--Chinese University of Hong Kong. / Bibliography: l. 74-86.

Simon, S.C., Chiu. / Thesis (M.Ph.)--Chinese University of Hong Kong. / Bibliography: leaves 65-71.

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