Biometrical, anatomical, and histological characterization of the Thai female dugong (Dugong dugon) reproductive system: Estimating sexual maturity and conservation applications https://doi.org/10.12982/VIS.2026.058
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Abstract
Dugongs (Dugong dugon) are vulnerable marine mammals with poorly understood reproductive biology in Southeast Asia. This study aimed to establish comprehensive reproductive parameters for Thai female dugongs and develop reliable maturity assessment criteria for conservation applications. Five female dugong carcasses were examined using biometric, gross anatomical, and histological analyses. Specimens were categorized as prepubertal (n = 2; body lengths 1.85 and 2.28 m) and pubertal (n = 3; body lengths 2.24, 2.59, and 2.80 m), based on ovarian size, ovarian morphology, and the presence of corpora lutea, or corpora hemorrhagica. Morphometric and histological examinations were conducted on all reproductive organs, and statistical comparisons were made between maturity groups. Body length was not a reliable indicator of sexual maturity due to overlapping ranges, whereas ovarian luteal structures (corpora lutea, hemorrhagica, and albicans) consistently distinguished mature from immature individuals. Vaginal and vestibular widths were significantly greater in pubertal specimens (P<0.05). Placental scars confirmed reproductive history, while multiple corpora lutea suggested polyovular cycles. Thai dugongs showed broader maturity size ranges compared to Australian populations. This study establishes the first regional reproductive baseline for Thai dugongs, providing morphological and histological criteria essential for field assessments and evidence-based conservation planning in Southeast Asian populations
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