Morphology, morphometry and ultrastructure of the Amazonian manatee (Sirenia: Trichechidae) spermatozoa

Abstract

This study describes the morphological, morphometric and ultrastructural characteristics of the Amazonian manatee Trichechus inunguis (Natterer, 1883) spermatozoon. The spermatozoa were obtained from a urine sample of an adult T. inunguis kept in captivity. The spermatozoa were analyzed by light and transmission electron microscopy. The head of Amazonian manatee spermatozoa had a flat oval shape and a well distinguishable midpiece. The mean dimensions of the spermatozoa were: head length, 7.49 ± 0.24 µm; head width, 3.53 ± 0.19 µm; head thickness, 1.61 ± 0.13 µm; midpiece length, 11.36 ± 0.34 µm; flagellum length, 40.91 ± 1.94 µm; total tail length, 52.16 ± 1.06 µm; total spermatozoon length, 60.08 ± 1.40 µm. The Amazonian manatee spermatozoa were similar in shape to other sirenian spermatozoa; however, presenting a different size. This study describes, for the first time, the morphometric and ultrastructural characteristics of the Amazonian manatee spermatozoa, and also demonstrates the possible use of spermatozoa retrieved from urine samples for biological studies

Morphometric and structural analysis of Florida manatee spermatozoa

“…However, in contrast to that described by Miller et al ( 2001 ), no pronounced annulus was observed in any of the analyzed samples. Our results are in accordance with those reported for the Amazonian manatee (Amaral et al, 2010 ) in which the annulus is not a prominent or pronounced feature of sirenian sperm.…”

“…The ultrastructural results of this study shared many similarities with features previously reported in sirenians (Amaral et al, 2010 ; Miller et al, 2001 ); however, some differences were observed from previous descriptions and additional structural components were described for the first time for this species. The head was ovate in shape and dorsoventrally flattened with an extensive acrosome that covered approximately 75% of the spermatozoon head.…”

“…Considering there was congruence in the morphometrics obtained using CASMA and SEM, we are confident that the automated software used in this study yielded accurate results. In comparison to other sirenian species, the morphometric values reported herein were most similar to those reported for the Amazonian manatee (Trichechus inunguis; Amaral, Lucci, Rosas, da Silva, & B ao, 2010), .5-91.5 0.5-11 2.5-46 0-0.5 0-26.5 1.5-59.5 0.5-3.5…”

“…The enlargement of ODF 9 is a previously unreported feature of Florida manatee sperm and it is currently unclear if this is shared across all sirenians. While not explicitly discussed, Figures 7 and 8 from Amaral et al (2010) show enlargement of ODFs in the Amazonian manatee. Figure 7 shows enlargement of ODFS 1, 5, and 6 while Figure 8 shows potential enlargement of ODFs 1, 5, 6, and 9 leading us to speculate that this is most likely a shared feature of sirenian sperm, although further investigation is needed to confirm this.…”

Abdominal ultrasound in amazonian manatee (Trichechus inunguis) (Natterer, 1883)

“…In manatees, the hepatic vascular architecture has visible vascular walls, with a hyperechoic appearance, turning to a coarse echotexture, with a visible delimitation of hepatic vessels (hepatic veins). The literature describes the portal vein of dogs and cats as a hyperechoic wall composed of fibrous and fat tissue, which is easily distinguishable in the (Best, 1982;Marmontel et al, 1992;Amaral et al, 2009;Amaral et al, 2010b), morphometric parameters in length-weight relation (Amaral et al, 2010a), and urinary parameters (Pantoja et al, 2010) have been carried out.…”