Anatomo-histological evaluation of male reproductive system of the juvenile Caiman crocodilus yacare / Evaluación anátomo-histológica del sistema reproductor del Caiman crocodilus yacare macho juvenil

SUMMARY: The Caiman crocodilus yacare was once close to extinction. Studies about the male reproductive tract may aid in their reproduction and conservation. In this work, after sedation and euthanasia, seven young male C. yacare were submitted to necropsy, and macroscopic evaluation of the reproductive system, while the three others were admitted for histological study. The histological sections were stained with Hematoxylin & Eosin and Masson's Trichrome. After opening the pleuroperitoneal cavity it was possible to identify that the testicles were disposed in pairs and attached to its dorsal surface. The epididymis showed elongated and convoluted shapes and were located at the cranial margin of the testicles, following its medial portion, which was the same portion that the "vas deferens" stems from until the opening of the cloaca. The crocodile phallus presented a tubular shape, with conical appearance, displaying little resistance while maintaining its flexibility, compatible with a fibrocartilaginous tissue. On light microscopic analysis it was possible to observe that the testis was delimited by the tunica albuginea. The seminiferous tubules were contorted, and the interstitial space was filled with interstitial tissue and Leydig cells. The epididymal ductus were covered with non-ciliated pseudostratified epithelium with cells varying between cuboidal and prismatic shapes. The ductus deferens were characterized by a narrow girth shrouded with non- ciliated pseudostratified prismatic epithelium. The phallus of the crocodile was covered with a non-keratinized squamous epithelium surrounded by connective tissue. The findings support anatomic and histologic knowledge Alligatoridae reproductive system, enabling further research in the C. yacare reproduction and conservation.

RESUMEN: El Caiman crocodilus yacare ha estado en peligro de extinción. Los estudios sobre el aparato reproductor del macho pueden ser de ayuda en su reproducción y conservación. En este trabajo, fueron sometidos a necropsia y evaluación macroscópica del aparato reproductor, siete machos jóvenes de C. yacare, mientras que otros tres fueron utilizados para su estudio histológico. Las secciones histológicas se tiñeron con hematoxilina y eosina y tricrómico de Masson. Después de examinar la cavidad pleuroperitoneal se pudo identificar que los testículos estaban dispuestos en pares y adheridos a su superficie dorsal. El epidídimo presentaba formas alargadas y contorneadas y se ubicaba en el margen craneal de los testículos, siguiendo su porción medial, que era la misma porción de donde parten los conductos deferentes hasta la apertura de la cloaca. El pene del cocodrilo presentaba forma tubular, de apariencia cónica, mostrando poca resistencia manteniendo su flexibilidad, compatible con un tejido fibrocartilaginoso. En el análisis microscópico óptico se pudo observar que el testículo estaba delimitado por la túnica albugínea. Los túbulos seminíferos estaban contorsionados y el espacio intersticial estaba lleno de tejido intersticial y células intersticiales (células de Leydig). El epidídimo estaba cubierto con epitelio pseudoestratificado no ciliado con células que variaban entre formas cuboideas y prismáticas. Los conductos deferentes se caracterizaron por una circunferencia estrecha envuelta en un epitelio prismático pseudoestratificado no ciliado. El pene del cocodrilo estaba cubierto con un epitelio escamoso no queratinizado rodeado de tejido conectivo. Los hallazgos corroboran el conocimiento de la anatomía del sistema reproductivo de Alligatoridae, lo que permite una mayor investigación sobre la reproducción y conservación de C. yacare.

Estado de la población del cocodrilo americano, Crocodylus acutus (Reptilia: Crocodilidae) y el caimán, Caiman crocodilus (Reptilia: Alligatoridae), en el Caribe central de Costa Rica

Dos especies de cocodrilianos han sido descritas en Costa Rica, el cocodrilo americano, Crocodylus acutus (Cuvier, 1807) y el caimán, Caiman crocodilus (Linnaeus, 1758). En Costa Rica se ha generado información de ambas especies, pero con énfasis en la vertiente del Pacífico, presumiblemente debido a su mayor desarrollo, lo cual ha acarreado mayor presión social hacia la atención de incidentes generados por el encuentro entre humanos y cocodrilos. El estudio se desarrolló durante el 2017 y en un área de aproximadamente 400 km2, caracterizada por tener una amplia densidad de cursos de agua que incluyen a los ríos: Matina, Pacuare, Reventazon y Parismina. En estos ríos se recorrió un promedio de 25 km desde la línea de costa hasta el interior del territorio, incluyendo los canales de Tortuguero, así como otros cuerpos de agua que conectan a estos ríos, lagunas importantes, y canales secundarios. Se realizaron tres repeticiones por segmento. Una población de 1 084 caimanes y 503 cocodrilos fue estimada, para una abundancia relativa de 8.64 y 2.80 ind/km respectivamente. Con respecto a caimanes poco más del 12 por ciento de los animales observados estaban en edad reproductiva, mientras que para cocodrilos sólo un 2 por ciento. La abundancia en los diferentes segmentos resultó ser significativamente diferente para ambas especies (Kruskal-Wallis, P 0.000). Mientras que la distribución por tallas de cocodrilos fue similar en todos los segmento (Kruskal-Wallis, P 0.15). Con 9 cocodrilos y 18 caimanes, reclutas o juveniles capturados, se calculó una proporción de sexos de 1.25 y 0.83 machos a hembras, para cocodrilos y caimanes respectivamente.

Two species of crocodilians have been described in Costa Rica, American crocodile, Crocodylus acutus (Cuvier, 1807), and caiman, Caiman crocodilus (Linnaeus 1758). In Costa Rica, data has been generated on both species, but populations in the Pacific have received more attention from researchers; presumably due to the fact that the Pacific slope has a greater development, which brings greater social pressure on the attention of the incidents generated by the encounter between humans and crocodiles. This study, performed during 2017, was done in an area of approximately 400 km2, characterized by having a wide and dense network of water courses, which includes the Matina, Pacuare, Reventazón and Parismina rivers. In these rivers, an average of 25 kilometers were traveled from the coastline up stream to the interior of the territory, including the Tortuguero canals, and other water bodies that connect these rivers, as well as in the most important lagoons and secondary channels. Three repetitions were made per segment. A population of 1 084 caimans and 503 crocodiles is estimated; for a sight count of 8.64 and 2.80 ind/Km respectively. Speaking of caimans, up to 12 por ciento of individuals of reproductive age were observed, while for crocodiles that number was only 2 por ciento. The abundance of both species in the different places studied, turned out to be significantly different for crocodiles and for caimans (Kruskal-Wallis, P 0.001). Likewise, the size distribution is similar for crocodiles reported in all environments (Kruskal-Wallis, p 0.15), while for caimans it indicates that there is a different distribution for sizes, according to the environment in which they are found (Kruskal -Wallis, P 0.001), with a bias against of the Pacuare and Matina rivers. It was possible to estimate a sex ratio of 1.25 and 0.83 males to females, in crocodiles and caimans respectively, with 9 and 11 captures in that same order, in recruit and juvenile sizes.

Characterization of Serum Complement Activity in Three Species of Crocodilians from Southeast Mexico.

To characterize the serum complement innate immune system in three species of crocodilians native to southeast Mexico. Methodology: Plasma collected from three wild crocodilian species native to southeast Mexico were exposed to sheep red blood cells (SRBCs) to measure hemolysis, which is used as an indication of serum complement immune activity. Results: Incubation of different volumes of plasma from Crocodylus acutus, Crocodylus moreletii, and Caiman crocodilus resulted in a volume-dependent increase in SRBC hemolysis. However, while maximum hemolysis for C. acutus and C. moreletii were both approximately five-fold higher than that of Ca. crocodilus. A kinetic study revealed that the hemolysis was rapid, with near-maximum activity recorded at 30 min for C. acutus and C. moreletii. However, Ca. crocodilus activity exhibited a significant increase (P<.5) only between one and two hours. A thermal analysis showed that the SRBC hemolysis was maximal at temperatures to which these species thermoregulate. The thermal profiles were similar for all three species, although the activity was lower for Ca. crocodilus (P<.01). The SRBC hemolysis was strongly inhibited by mild heat treatment (56°C,30 min) and also by EDTA, indicating that the hemolytic activity was probably due to the presence of crocodilian serum complement activity. The EDTA-inhibited activity was restored by the addition, of a 20mM excess of Ca2+or Mg2+, but not Fe2+orCu2+, thus exhibiting the specific need for Ca2+orMg2+. Conclusions: The serum complement activities of C. acutus and C. moreletii are much higher (P<.01) than Ca. crocodilus, which may be related to the maximum sizes and increased aggressive natures of C. acutus and C. moreletii.

Study on antibacterial effects of crocodilian plasma in vitro / 中国海洋药物

Objective To investigate the effects of crocodilian plasma on 12 bacteria(including G+ bacteria and G-bacteria) lines in vitro.Methods The bacteria CFUs on nutrient broth agar plates were determined after bacteria and crocodilian plasma incubated together for 1h.Then effects of the samples on the survival rate of various concentrations of bacteria were calculated.To evaluate the antibacterial spectrum of crocodilian plasma,the zones of bacterial inhibition were measured through agar disk method.Results and Conclusion Crocodilian plasma had superior bactericidal effects on Escherichia coli M421C1,O111B4,E240-3 LT,Micrococcus catarrhalis,Shiga's bacillus,Pseudomonas aeruginosa and Diplococcus pneumoniae.The results indicated why wound of crocodilian by tearing each other was not susceptible,and crocodilian plasma could be developed a natural antibacterials.