| Summary: | Thesis (MSc)--University of Stellenbosch, 2002. === ENGLISH ABSTRACT: Specialized skin scales (generation glands) and undifferentiated skin scales were
compared in three species of cordylid lizard, viz. Cordy/us cordy/us, Pseudocordy/us
micro/epidotus and P. capensis. These skin derivatives were histologically examined
and compared, using data existing in literature (Maderson, 1966; 1967; 1968a) with
similar structures in gekkonids. Histological descriptions of cordylid skin structure
were the same as those shown for gekkonids. Three types of generation glands
were identified in cordylids (Van Wyk & Mouton, 1992), and these proved to be
different to those existing in gekkonid species. These three types of generation
glands were further compared regarding their ecdysis histology, which proved to be
identical, thus, these glands differ only on gross morphological structure. Skin of all
three species was also compared with regard to ecdysis, and while the histology of
all three was identical, shedding activity was shown to differ in all three species. P.
micro/epidotus displayed dormancy in the germinative layer for much longer periods
of the year than either of the other two species, while P. capensis displayed very little
dormancy. C. cordy/us displayed an intermediate pattern of ecdysis activity and
dormancy. Autoradiography was performed on all species in both ecdysis activity
and dormancy periods, to compare mitotic activity patterns in these periods.
Generation gland activity appeared to correlate well with known testosterone peaks
in the testicular cycle in all three species. Asynchrony between generation glands
and skin scales was shown in all three species. === AFRIKAANSE OPSOMMING: GENERASIEKLIERE EN VERVELLINGSIKLUSSE IN GORDELAKKEDISSE
(SAURIA: CORDYLIDAE)
Drie spesies gordelakkedisse, Gordy/us cordy/us, Pseudocordy/us micro/epidofus en
P. capensis, se gespesialiseerde velskubbe (generasiekliere) en gewone velskubbe
word vergelyk. Hierdie velskubbe word deur histologiese metodes geëksamineer en
vergelyk, met gebruik van data wat reeds in die literatuur bestaan (Maderson, 1966;
1967; 1968a), met soortgelyke strukture in Gekkonidae. Histologiese beskrywing
van Cordylidae veistruktuur was identies met dié van Gekkonidae. Drie tipes
generasiekliere was geïdentifiseer in gordelakkedisse (van Wyk & Mouton, 1992), en
hulle verskil gedeeltlik van naverwante strukture in Gekkonidae. Hierdie drie tipes
generasiekliere was verder vergelyk met betrekking tot hulle vervellingsiklus
histologie, wat identies was. Dus verskil hulle net met betrekking tot hulle vorm. Vel
is ook vergelyk met dieselfde metodes. Alhoewel daar geen verskille was met
betrekking tot hulle histology nie, was die tye van aktiwiteit van kiem-sellae
beduidend verskillend in alle spesies. In P. micro/epidofus het die kiem-sellaag
russtadium baie langer geduur as in die ander twee spesies, terwyl P. cepensis
amper geen russtadium getoon het nie. G. cordy/us het 'n intermediêre
gedragspatroon vertoon tussen aktiewe en rustende fase met betrekking tot sy
vervellingsiklus. Outoradiografie is gebruik op elke spesie, in beide aktiewe en
rustende vervellingsfases, om verskille in mitotiese aktiwiteit te wys. Generasieklier
aktiwiteit blyk te korreleer met pieke van testosteroonvlakke van die testikulêre siklus
in al drie spesies. Asinkronie is aangetoon tussen generasiekliere en velskubbe in al
drie spesies.
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