Historical perspective: Hormonal regulation of behaviors in amphibians

Breeding under unpredictable conditions: Annual variation in gonadal maturation, energetic reserves and plasma levels of androgens and corticosterone in anurans from the Brazilian semi-arid

In March 2014, the Asian toad Duttaphrynus melanostictus was reported from Madagascar's second largest city and main port Toamasina, raising immediate concerns about the invasive nature of the newl...

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The New Toad in Town: Distribution of the Asian Toad, Duttaphrynus Melanostictus, in the Toamasina Area of Eastern Madagascar:

This study describes the male reproductive cycle of Dendropsophus minutus (Peters, 1872) based on testicular morphometric analysis, related to climatic conditions. Fifty individuals where collected in Sao Jose do Rio Preto, Sao Paulo. After macroscopic analysis, the testes were submitted to histological routine, fixed with Bouin, embedded in historesin. Sections of 2 µm were stained with 1% toluidine blue and observed to the microscope. The testes of D. minutus are small organs (length 1.90 ± 0.13 mm), whitish, oviform and found in the abdominal cavity. They are located in the cranial extremity of the kidneys and present asymmetry as far as position. According to statistical analyses, there is no intra-individual variation in length and weight of the testes, as well as in the area and diameter of the seminiferous locules. Concerning the testicular histology, it was possible to identify, throughout the year, in seminiferous locules, all the cellular types from the spermatogenic lineage, characterizing a continuous gametogenesis, corroborated by ecological and behavioral factors. Information about testicular morphometry and reproductive cycle has important biological value for anurans in the neotropics.

/pdf/morfometria-testicular-durante-o-ciclo-reprodutivo-de-2m2pty0ozo.pdf

Morfometria testicular durante o ciclo reprodutivo de Dendropsophus minutus (Peters) (Anura, Hylidae)

The spermatogenesis of Pseudis limellum, from the Southern Pantanal, Brazil, was studied from July 1995 to May 1996, through histological sections of the testis. The cells could be differentiated as: primary spermatogonia, large cells, generally with bilobed nucleus; secondary spermatogonia, smaller cells, with darker cytoplasm, chromatin of radial form; primary and secondary spermatocytes, differentiated according to the different stages of the nucleus during the successive cells divisions. Furthermore, we observed cells in process of morphologic differentiation: rounded spermatids much smaller, with nucleus containing chromatin in compacting process and cytoplasm reduction; elongated spermatids, generally parallel organized in well defined bundles, with the anterior region directed toward the periphery of the seminiferous tubule and the tail directed toward the lumen. Spermatozoa are free in the lumen of the seminiferous tubule. All the cells are organized as cysts, which are supported by a large amount of Sertoli cells. The spermatogenesis in P. limellum is very similar to that of other anurans, but peculiarities were observed regarding the organization of the germ cells, the great amount of free Sertoli cells in the lumen of testis collected in May, and the long cytoplasmatic extensions of the cells bearing pigments and involving the seminiferous tubule. The diameter of the seminiferous tubule (SD) exhibited an annual mean of 251.79 +/- 37.57 microm. Spermatozoa number by seminiferous tubule (SN) exhibited an annual mean of 306.66 +/- 39.83, also with higher and lower values at each month. Variations in SD and SN were not significantly correlated with climatic variables. In this species, reproduction occurs throughout the year in ponds and flooded areas, despite the seasonal climate of the Pantanal. Although males varied in their annual reproductive activity, they were considered potentially reproductive in all months throughout the year.

Morphologic and morphometric analysis of testis of Pseudis limellum (Cope, 1862) (Anura, Hylidae) during the reproductive cycle in the Pantanal, Brazil.

The male reproductive cycle of the toad, Bufo melanostictus, was studied with emphasis on spermatogenic activity, plasma androgen, and changes in the weights of testes, liver, and fat bodies. A total of 98 toads were collected between March 1990 and March 1991 in central Taiwan. Histological evidence indicated that the spermatogenic cycle of this toad is of a fluctuating continuous type. Although cell nests of all spermatogenic types were present every month of the year, the greatest intensity of spermatogenic activity, as expressed by the presence of sperm bundles, occurred in March. Both testicular weight and plasma androgen levels peaked in March. The weights of fat bodies peaked in July, which was not coincident with the beginning of breeding. Combined data from spermatogenic activity, plasma androgen levels, and changes in the weights of testes, fat bodies, and livers revealed that B. melanostictus is a continuous breeder. However, its annual reproductive cycle could be divided into 4 period...

https://bioone.org/journals/Zoological-Science/volume-14/issue-3/zsj.14.497/Male-Reproductive-Cycle-of-the-Toad-span-classgenus-speciesBufo-melanostictus/10.2108/zsj.14.497.pdf

Male Reproductive Cycle of the Toad Bufo melanostictus in Taiwan

Wen-San Huang, Jun-Yi Lin and John YUh-lin Yu (1996) The male reproductive cycle of the toad, Buto bankorensis, in Taiwan. Zoological Studies 35(2): 128-137. Studies of the male reproductive cycle in the toad, Buto bankorensis were conducted on spermatogenetic activity, direct measurements of plasma androgen, and changes in the weights of testes, liver and fatbody. A total of 110 male Buto bankorensis were collected from March 1990 to March 1991 in central Taiwan. Histological evidence indicates that the spermatogenetic cycle of this toad is of a potentially continuous type. Although cell nests of all spermatogenic types were present every month of the year, the greatest intensity of spermatogenetic activity (sperm bundles and mature sperm) occurred during August to November. Plasma androgen levels exhibited a significant difference in level between September and June (mean values = 93 nglml and 2.5 nglml, respectively). The weights of fat bodies peaked during the months of May, June and July, coincident with the beginning of breeding, and they had regressed in December by the end of the period of intense spermatogenetic activity. Testicular weight increased slowly in August and peaked in September. Combined data from spermatogenetic activity, plasma androgen, and changes in weights of testes, fat bodies, and livers showed that B. bankorensis is a potentially continuous breeder. However, its annual reproductive cycle could be clearly divided into these periods: 1) breeding period (August to November); 2) postbreeding period (December to February); 3) reproductive energy preservation period (March to May); and 4) torpid period (June to July).

http://zoolstud.sinica.edu.tw/Journals/35.2/128.pdf

The Male Reproductive Cycle of the Toad, Suto bankorensis, in Taiwan

Reproductive patterns of female house shrew (Suncus murinus) inhabiting central Taiwan were studied from September 1990 to February 1992 with animals collected monthly. The annual average body weight was 37.4 g for adults (N=198), and 23.2 g for juveniles (N=18), respectively. The reproductive females (pregnant and lactating) were found all the year round with higher percentages (more than 80%) in spring-summer. The average litter size was 2.9 (range: 1–6). The levels of plasma estradiol-17 β in adult females were higher in March-June (140 pg/ml), and decreased gradually to 98 pg/ml in January-February. Plasma levels of estradiol-17 β in pregnant and lactating females were significantly greater than those of non-pregnant adults and of juveniles. Ovarian weights, plasma levels of estradiol-17 β, and pregnancy rate were correlated with day length. The pre-implantation mortality and post-implantation mortality of the embryos were 6.9% and 1.6%, respectively. The present study has demonstrated that t...

https://bioone.org/journals/Zoological-Science/volume-16/issue-5/zsj.16.819/Annual-Reproductive-Patterns-of-Female-House-Shrew-span-classgenus-speciesSuncus/10.2108/zsj.16.819.pdf

Jun-Yi Lin

Papers

Male Reproductive Cycle of the Toad Bufo melanostictus in Taiwan

The Male Reproductive Cycle of the Toad, Suto bankorensis, in Taiwan

Annual Reproductive Patterns of Female House Shrew, Suncus murinus, in Taiwan