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Sretarugsa, Prapee; Weerachatyanukul, Wattana; Chavadej, Jittipan; Kruatrachue, Maleeya; Sobhon, Prasert

doi:10.2306/scienceasia1513-1874.2001.27.001

Cited by 16 publications

(1 citation statement)

References 30 publications

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“…The developing oocytes during the ovarian development and seasonal variation in H. rugulosus/R. tigerina was examined by histological and ultrastructural study (TEM) by Sretarugsa et al (2001). In adult frog, the developing oocytes can be classified into 6 stages including stage I-II oocyte (previtellogenic stage), stage III-IV oocyte (vitellogenic stage) and stage V-VI oocyte (vitellogenic and fully growth stages).…”

Section: Reproductive Biology In H Rugulosusmentioning

confidence: 99%

Gonadal sex differentiation of rice field frog hoplobatrachus rugulosus (wiegmann, 1834)

Traijitt¹

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The rice field frog Hoplobatrachus rugulosus, a species widely distributed in Thailand, has potential to be a model in many fields of research. A preliminary study demonstrated that the gonadal differentiation in this frog showed tendency to be an undifferentiated type since all individuals had ovaries at complete metamorphosis. However, the information was still unclear. Therefore, this study aimed to investigate the chronology and pattern of gonadal sex differentiation as well as steroidogenic potential of gonadal tissues during development. The frog embryos were obtained by stimulating fertilization in laboratory under natural light and temperature conditions. Their developmental stage was identified using Gosner (1960) system. The time period during each stage of development was also recorded. H. rugulosus spent 25-33 days for development to complete metamorphosis. The gonad was firstly observed by stereomicroscope at Gosner stage 33 (9-12 days post hatch, dph), while the testis and ovary were distinguishable by morphology from 3–4 weeks after metamorphosis. Histological analysis showed that genital ridge formation began at stage 25 (1-2 dph) and ovarian differentiation began at stage 36 (13-17 dph). The developing ovary appeared with numerous primary oogonia which developed into oocytes, while the medulla regressed to form an ovarian cavity. During metamorphosis, only an ovary was observed. Testicular differentiation began later, during the first week after metamorphosis, and occurred via an intersex condition. The intersex gonads contained developing testicular tissue with both normal and atretic oocytes. The fully developed testis was firstly identified at 6 weeks after metamorphosis. Thus, the pattern of gonadal sex differentiation in H. rugulosus is an undifferentiated type, in which only female gonads are observed during metamorphosis and intersex and male gonads are observed later. For steroidogenic potential of gonad, the expression level of mRNA encoding cytochrome P450 17-hydroxylase/C17–20 lyase (CYP17) and cytochrome P450 aromatase (CYP19) were observed by quantitative real-time RT-PCR and localization of CYP17 mRNA in the tissues was observed by in situ hybridization. The results showed that CYP17 mRNA levels in male group at 4-11 weeks after metamorphosis showed a higher level than those of other groups. This result corresponded to their localization in the gonadal tissues that the CYP17 signals were specifically detected in Leydig cells of testicular tissue in both testes and intersex gonads at 4-16 weeks after metamorphosis but undetectable in all ovary samples. The CYP19 mRNA levels in female group at 4-11 weeks after metamorphosis was higher than those of other groups which corresponded with the histological results that the number of oocytes and follicular cells were increased, indicating potential steroidogenic function of the ovary. In intersex group at 4-11 weeks after metamorphosis, the level of CYP17 mRNA was high, whereas the level of CYP19 mRNA was relatively lower. It could be suggested that the testicular tissue of intersex gonad has developed and had steroidogenic function, while the ovarian tissue of intersex gonad may not function. Based on the present results, the role of CYP17 and CYP19 mRNA in sex differentiation in H. rugulosus may occur after the gonadal sex differentiated and the steroidogenic potential of the gonads exhibited sexual dimorphic pattern. These results provide a crucial basis for further research on developmental biology in anuran species.

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Section: Reproductive Biology In H Rugulosusmentioning

confidence: 99%

Gonadal sex differentiation of rice field frog hoplobatrachus rugulosus (wiegmann, 1834)

Traijitt¹

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Ultrastructural observations of previtellogenic ovarian follicles of the caecilians Ichthyophis tricolor and Gegeneophis ramaswamii

Beyo

Sreejith

Divya

et al. 2007

Journal of Morphology

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The ultrastructural organization of the previtellogenic follicles of the caecilians Ichthyophis tricolor and Gegeneophis ramaswamii, of the Western Ghats of India, were observed. Both species follow a similar seasonal reproductive pattern. The ovaries contain primordial follicles throughout the year with previtellogenic, vitellogenic, or postvitellogenic follicles, depending upon the reproductive status. The just-recruited primordial follicle includes an oocyte surrounded by a single layer of follicle and thecal cells. The differentiation of the theca into externa and interna layers, the follicle cells into dark and light variants, and the appearance of primordial yolk platelets and mitochondrial clouds in the ooplasm mark the transition of the primordial follicle into a previtellogenic follicle. During further development of the previtellogenic follicle the following changes occur: i) the theca loses distinction as externa and interna; ii) all the follicle cells become the dark variant and increase in the complexity of ultrastructural organization; iii) the nucleus of the oocyte transforms into the germinal vesicle and there is amplification of the nucleoli; iv) the primordial yolk platelets of the cortical cytoplasm of the oocyte increase in abundance; v) the mitochondrial clouds fragment and the mitochondria move away from the clouds, leaving behind the cementing matrix, which contains membrane-bound vesicles of various sizes, either empty or filled with a lipid material; vi) the perivitelline space appears first as troughs at the junctional points between the follicle cells and oocyte, which subsequently spread all around to become continuous; vii) macrovilli and microvilli develop from the follicle cells and oocyte, respectively; and viii) the precursor material of the vitelline envelop arrives at the perivitelline space. The sequential changes in the previtellogenic follicles of two species of caecilians are described.

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Accumulation of yolk in a caecilian (Gegeneophis ramaswamii) oocyte: A light and transmission electron microscopic study

Beyo

Divya

Oommen

et al. 2008

Journal of Morphology

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There is a paucity of information on the female reproductive biology of the caecilian amphibians when compared with the other vertebrate groups. Hence, the accumulation of nutrient reserves in the form of yolk and formation of yolk platelets were studied in Gegeneophis ramaswamii, adopting light microscopic histological and transmission electron microscopy analysis. Previtellogenic as well as vitellogenic follicles were observed in appropriate preparations. On the basis of the source and the routes of entry, we identified four types of yolk precursor materials, precursors 1 to 4. The earliest material appearing in the oocyte consists of abundant lipid vesicles during the previtellogenic phase, i.e., much before the follicular epithelium is fully established. This is a contribution from the oocyte mitochondria, which we identified as yolk precursor material 1, and it is autosynthetic. Once the follicle cell-oocyte interface is fully established, there is an accumulation of the principal component of the heterosynthetic yolk by sequestration from the blood through the intercellular spaces between follicle cells in a pinocytic process. This we identified as yolk precursor material 2. There was also an indication of a lipidic yolk material synthesis in the follicle cells sequestered from maternal blood through the follicle cells in an endocytic process in which the macrovilli of follicle cells and the microvilli of the oocyte play a role. This we identified as yolk precursor material 3. Contribution to the yolk of peptidic, glycosidic, and/or lipidic material synthesized in the vitellogenic oocyte was also indicated. This we identified as yolk precursor material 4. The sequential development of intercellular associations and indications of synthesis/sequestration of the yolk have been traced. Thus, we report the mechanistic details of synthesis/sequestration of the yolk materials in a caecilian.

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Cited by 16 publications

References 30 publications

Gonadal sex differentiation of rice field frog hoplobatrachus rugulosus (wiegmann, 1834)

Gonadal sex differentiation of rice field frog hoplobatrachus rugulosus (wiegmann, 1834)

Ultrastructural observations of previtellogenic ovarian follicles of the caecilians Ichthyophis tricolor and Gegeneophis ramaswamii

Accumulation of yolk in a caecilian (Gegeneophis ramaswamii) oocyte: A light and transmission electron microscopic study

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