We studied the morphological characteristics and seasonal changes of the bulbourethral gland of Eidolon helvum in a typical African tropical environment. Forty‐eight bulbourethral glands were examined using gross anatomical, histological, histochemical, and ultrastructural techniques during the early rainy, late rainy, and peak dry seasons. The pear‐shaped bilateral bulbourethral glands were located extra‐abdominally in the inguinal region. Trabeculae from the capsule divided the parenchyma into numerous lobules of tubuloalveolar glandular acini. The mucosa was covered by a simple columnar epithelium consisting up of principal secretory cells, columnar dense cells and basal cells, which were progressively pronounced during the dry season. The principal cells contained eosinophilic granules, which were PAS positive while the dense cells did not show affinity for the stains. The mean gross weights, acini diameters, and epithelial heights were greater during the rainy season than the dry season. Ultrastructural evaluation showed that the cytoplasm of the principal cells contained well‐developed Golgi complexes, rough endoplasmic reticulum, mitochondria, and secretory vesicles of varying electron densities and sizes. The secretory vesicles were numerous during the early rainy season, decreased during the late rainy season and were scanty during the peak dry season. The simple columnar epithelium observed during the rainy season was replaced by an undefined stratified epithelium during the dry season, and this was associated with cellular degenerations and regenerations. In conclusion, E. helvum has a typical mammalian bulbourethral gland, with a unique cell type, the dense cell whose functions are not well‐understood. The gland exhibits cyclical seasonal variation in structure and secretory activity; being active during the early rainy season (breeding season), and showing the lowest activity during the dry season (non‐breeding season). Glandular epithelial cell renewal occurs during the dry season in preparation for the next breeding season.

中文翻译：

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非洲稻草色果蝠 Eidolon helvum 尿道球腺的组织学、超微结构和季节性变化

我们研究了典型的非洲热带环境中 Eidolon helvum 的尿道球腺的形态特征和季节变化。在早雨、晚雨和旱季高峰期间，使用大体解剖学、组织学、组织化学和超微结构技术检查了 48 个尿道球腺。梨形双侧尿道球腺位于腹股沟区腹外。来自囊的小梁将实质分成许多小管肺泡腺泡的小叶。黏膜被简单的柱状上皮覆盖，由主要分泌细胞、柱状致密细胞和基底细胞组成，在旱季逐渐明显。主细胞含有嗜酸性颗粒，PAS 阳性，而致密细胞对染色没有亲和力。雨季的平均毛重、腺泡直径和上皮高度高于旱季。超微结构评估表明，主细胞的细胞质含有发育良好的高尔基复合体、粗面内质网、线粒体和不同电子密度和大小的分泌囊泡。雨季初期分泌小泡较多，雨季后期分泌小泡减少，旱季高峰期分泌小泡稀少。在雨季观察到的简单柱状上皮在旱季被不确定的分层上皮取代，这与细胞变性和再生有关。总之，E。helvum 具有典型的哺乳动物尿道球腺，具有独特的细胞类型，其功能尚不清楚的致密细胞。腺体在结构和分泌活动方面表现出周期性的季节性变化；在雨季早期（繁殖季）活跃，在旱季（非繁殖季）活跃度最低。腺上皮细胞更新发生在旱季，为下一个繁殖季节做准备。