The morphological and physiological changes during the reproductive cycle of the female rock lizard, Agama atra Daudin, 1802

[摘要] ENGLISH ABSTRACT:Morphological and physiological changes during the annual reproductive cycleof the female oviparous lizard, Agarna atra, are described.1 •2.3.4.5.6.7.8.The onset of the breeding cycle was marked by vitellogenic ovarian hyper=trophy (September) and ovulation of the first clutch occurred in c;x:tober,after which a second clutch was produced. During February novitellogenic females were collected.The onset and tennination of the breeding cycle, correlated with the springand aufumnal equinox as well as increased and decreased mean monthly airtemperatures. Photothennal regimes ( 14L : 10 D and 25 - 45 °C) inducedvitellogenesis in females collected during the winter months.Histological changes of the growing oocyte were studied. CXJgonial pro=liferation, oogenesis and folliculogenesis in Agama. atra appeared to beconsistant with the general squamate pattern. Post-ovulatory and twotypes of atretic follicles are described.The fatbody cycle showed an inverse correlation with ovarian hypertrophy.Total plasma cholesterol varied between 200 and 350 -1 mg. 1 OOml • Adecrease was correlated with ovarian hypertrophy and fatbody depletion.The total plasma protein concentration decreased during vitellogenesis·and increased before ovulation. The plasma proteins separated intofive major fractions upon cellulose acetate electrophoresis. Ovarianhypertrophy was accompanied by an increase in fraction II (similarm::>bility .as human Beta-globulins). Fractions V (albumin), IV andIII (Alpha-globulins) were conccmitantly decreased.Plasma calcium concentrations increased significantly (P<0.001) duringvitellogenesis.A post-ovulator.1 progesterone surge (7450 pg. 0.2ml-1) with the presenceof well developed corpora lutea. The onset of a second vitellogeniccycle ~fs evident during relative high prbgesterone levels (1 500 pg.0.2rill ). '9. The oviducal index showed a high correlation with ovarian development,indicating oestrogenic activity.10. Oestrogen and oestrogen plus progesterone treabnent resulted in increasedplasma vitellogenic paramters in the male, Agama atra. Progesteronealone had no effect.11. Both PMSG and HCG treabnent (4 IU per lizard) induced vitellogenesis infemales containing quiescent ovaries, although PMSG was found to be morepotent in inducing ovulation.12. No significant effect of arginine-vasotocin and oxytocin on ovipositioncould be observed.KEY WORDS: Squamata, Ag3I1la, Female breeding season, environmental, seasonalchanges, ovarian histology, fatbody, cholesterol, plasma proteins, calcium,oviduct, progesterone, vitellogenesis, gonadotropins, oviduct contractility.

[发布机构] Stellenbosch University