Reproductive endocrinology of the explosively breeding desert spadefoot toad, Scaphiopus couchii
Reproductive endocrinology of the explosively breeding desert spadefoot toad, Scaphiopus couchii
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DOI：
10.1006/gcen.1996.6805
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发表时间：
1997-01-01
影响因子：
2.7
通讯作者：
Moore, MC
中科院分区：
文献类型：
--
作者：
Harvey, LA;Propper, CR;Moore, MC
锄足蟾蜍（Scaphiopus couchii）是一种爆炸性繁殖的沙漠两栖动物，它表现出两个假设的特征，以选择分离的繁殖模式：它生活在恶劣的环境中，并且它的繁殖期非常短但可预测。我们通过测量自由生活的 S. couchii 种群中的血浆类固醇激素和配子发生周期来检验这些因素选择分离繁殖周期的假设。血液和组织样本取自繁殖前、召唤（仅限雄性）、混合和繁殖后蟾蜍。在雄性中，血浆睾酮 (T)、二氢睾酮 (DHT) 和皮质酮 (B) 在生殖群体中存在显着差异，其中鸣叫蟾蜍和丛蟾蜍中每种类固醇的水平最高。在女性中，测量血浆 T、DHT、B、孕酮 (P) 和雌二醇 (E(2))；除 B 外，所有类固醇在交配组之间均发生显着变化。血浆T和E(2)在预交配和交配雌性中最高，而P和DHT仅在交配雌性中最高。初级精原细胞（SPG I）、次级精原细胞（SPG II）、精母细胞、精细胞（SPT）和嵌入支持细胞的精子（SPS）在雄性繁殖群体中均发生显着变化。尽管所有阶段都存在于所有繁殖群体中，但精子的早期阶段（SPG I 和 SPG II）在繁殖后雄性中最多，而晚期阶段（SPT 和 SPS）在交配前、召唤和交配雄性中最高。在雌性中，卵母细胞 I、II、III、V 和 VI 阶段以及闭锁卵泡在交配组之间也存在显着差异。交配前的雌性卵巢以晚期（V 和 VI）卵母细胞为主，这些卵母细胞随后在抱合期间排卵。在配种后的雌性中，第二阶段和第三阶段卵母细胞数量的增加表明卵子发生正在顺利进行。这些结果表明配子发生的各个方面都发生在两性的繁殖期间和之后。尽管结果表明，性腺活动在性活动期间很高，这表明 S. couchii 最符合 Crews 定义的相关繁殖模式（1984，Horm. Behav. 18, 22-28），但我们还发现，性腺活动在繁殖季节之后仍然持续。因此，S. couchii 并不完全符合相关模式。 (C) 1997 学术出版社
The spadefoot toad, Scaphiopus couchii, is an explosively breeding, desert dwelling amphibian that shows two characteristics hypothesized to select for a dissociated breeding pattern: it lives in a harsh environment and it has a very short, but predictable breeding period. We tested the hypothesis that these factors select for a dissociated breeding cycle by measuring plasma steroid hormones and the gametogenic cycles in a free-living population of S. couchii. Blood and tissue samples were obtained from prebreeding, calling (males only), amplexed, and postbreeding toads. In males, plasma testosterone (T), dihydrotestosterone (DHT), and corticosterone (B) differed significantly among reproductive groups, with calling and amplexing toads having the highest levels of each of these steroids. In females, plasma T, DHT, B, progesterone (P), and estradiol (E(2)) were measured; all steroids except B changed significantly among mating groups. Plasma T and E(2) were greatest in prebreeding and amplexed females, while P and DHT were highest only in amplexed females. Primary spermatogonia (SPG I), secondary spermatogonia (SPG II), spermatocytes, spermatids (SPT), and spermatozoa embedded in Sertoli cells (SPS) all changed significantly among male breeding groups. Although all stages were present in all breeding groups, early stages of spermatozoa (SPG I and SPG II) were greatest in postbreeding males, while late stages (SPT and SPS) were highest in prebreeding, calling, and amplexing males. In females, oocyte stages I, II, III, V, and VI and atretic follicles also differed significantly among mating groups. Prebreeding female ovaries were dominated by late-stage (V and VI) oocytes which were subsequently ovulated during amplexus. In postbreeding females, oogenesis was well under way as indicated by the rising numbers of stage II and III oocytes. These results indicate that aspects of gametogenesis occur during and after breeding in both sexes. Although the results demonstrate that gonadal activity was high during the period of sexual activity, suggesting that S. couchii most closely fits an associated pattern of reproduction as defined by Crews (1984, Horm. Behav. 18, 22-28), we also found that gonadal activity continued past the breeding season. For this reason, S. couchii does not completely conform to an associated pattern. (C) 1997 Academic Press