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| Author(s): |
Lívia Cristina dos Santos
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB) |
| Defense date: | 2009-02-02 |
| Examining board members: |
Selma Maria de Almeida Santos;
Marta Maria Antoniazzi;
Marcio Roberto Costa Martins
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| Advisor: | Selma Maria de Almeida Santos |
| Abstract | |
The reproductive biology of the Amphisbaenia (worm lizards) is poorly known, in part because of their fossorial habits, which make difficult studies on the field and their capture. Leposternon microcephalum is a species widespread in Brazil, and accommodates in the family Amphisbaenidae. This work aimed to study features of the reproductive biology of L. microcephalum from Southeastern Brazil, such as fecundity, time of hatching, occurrence of oviposition in ant nests, size of sexual maturity, gonadal sintopy and sexual dimorphism on body length and width. It also aimed to analyze follicular and testicular cycles and to characterize the morphology of gonads and genital ducts. For that, museum specimens collected on different months of the year were used for analyses and measurements of testes, vas deferens, ovarian follicles and oviducts. Those organs were also analyzed histologically by light microscopy, to describe theirs structure and to better characterize the sexual cycle. Ant nests were excavated to look for eggs. The female reproductive cycle were estimated to take at least two years. The most part of yolk deposition occurs during the last three months before ovulation, and it is of the vernal type (pre-nuptial). Ovulation takes place approximately at the same time as mating, between November and December. Spermatogenesis is of the mixed type (type II B), and the peak of spermatozoa production occurs approximately two months before mating. There is a short phase of sperm storage in vas deferens. By that time, vas deferens epithelium becomes secretory. After the spermatogenesis, there is a great involution of testes. The number of eggs produced by each female probably varies between two and six. According to the structure seen under light microscope, the oviducts are divided in four regions: vagina, uterus, anterior infundibulum and posterior infundibulum. Sexual maturity can be inferred from the opacity of genital ducts, and it is probably attained in three years. The right gonad is usually anterior to the left one, and there is an overlapping region, in which the two gonads are arranged side by side. Sexual dimorphism was not observed, and oviposition in ant nests does not seem to be obligatory. (AU) | |