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Morphology of the genital organs of male and female giant anteaters (Myrmecophaga tridactyla)

BACKGROUND: The giant anteater belongs to the supraorder Xenarthra which occupies a systematically isolated position among placental mammals. The species is categorized as Vulnerable by the International Union for Conservation of Nature, and understanding its reproductive characteristics is critical...

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Autores principales: Fromme, Lilja, Yogui, Débora R., Alves, Mario Henrique, Desbiez, Arnaud L.J., Langeheine, Marion, Quagliatto, André, Siebert, Ursula, Brehm, Ralph
Formato: Online Artículo Texto
Lenguaje:English
Publicado: PeerJ Inc. 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8364315/
https://www.ncbi.nlm.nih.gov/pubmed/34447632
http://dx.doi.org/10.7717/peerj.11945
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author Fromme, Lilja
Yogui, Débora R.
Alves, Mario Henrique
Desbiez, Arnaud L.J.
Langeheine, Marion
Quagliatto, André
Siebert, Ursula
Brehm, Ralph
author_facet Fromme, Lilja
Yogui, Débora R.
Alves, Mario Henrique
Desbiez, Arnaud L.J.
Langeheine, Marion
Quagliatto, André
Siebert, Ursula
Brehm, Ralph
author_sort Fromme, Lilja
collection PubMed
description BACKGROUND: The giant anteater belongs to the supraorder Xenarthra which occupies a systematically isolated position among placental mammals. The species is categorized as Vulnerable by the International Union for Conservation of Nature, and understanding its reproductive characteristics is critical for future conservation efforts. METHODS: Gross and microscopic anatomy of the genital organs of 23 male and 21 female adult and young roadkill giant anteaters in Brazil were studied. RESULTS: Male giant anteaters presented a short conical penis, intraabdominal testes, and prostate, vesicular and bulbourethral glands. A tubular remnant of the partially fused Müllerian ducts extended from the seminal colliculus through the prostate gland, continued cranially in the genital fold, bifurcated, and attached with one elongation each to the left and right epididymal corpus. The structure presented a total length of up to 10 cm and contained a yellowish liquid in its lumen. Histologically, the caudal section of this structure resembled the female vagina, the middle portion corresponded to the uterus, and the extensions showed characteristics of uterine tubes. In adult female giant anteaters, ovoid ovaries with occasional seminiferous cord-like structures were observed. The animals possessed a simple uterus, which was directly continuous with the vaginal canal. The caudal portion of the vagina had two lumina, separated by a longitudinal septum and opening into two apertures into the vaginal vestibule, cranial to the urethral opening. In the urethral and the lateral vestibular wall, glandular structures with characteristics of male prostate and bulbourethral glands, respectively, were found. The vestibule opened through a vertical vulvar cleft to the exterior. A pair of well-differentiated Wolffian ducts with a central lumen originated ventrally at the vaginal opening into the vestibule and passed in a cranial direction through the ventral vaginal and uterine wall. Each duct extended highly coiled along the ipsilateral uterine tube until the lateral pole of the ovaries where it merged with the rete ovarii. DISCUSSION: The reproductive morphology of giant anteaters reveals characteristics shared with other Xenarthrans: intraabdominal testes, a simple uterus, and a double caudal vagina. The persistence of well-differentiated genital ducts of the opposite sex in both males and females, however, singles them out among other species. These structures are the results of an aberration during fetal sexual differentiation and possess secretory functions. The possibility of a pathological degeneration of these organs should be considered in reproductive medicine of the species. CONCLUSION: Knowledge of the unique reproductive characteristics of the giant anteater is essential for future reproductive management of the species. Additionally, further research on the peculiarities of the persisting genital duct structures might help to understand sexual differentiation in placental mammals in general.
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spelling pubmed-83643152021-08-25 Morphology of the genital organs of male and female giant anteaters (Myrmecophaga tridactyla) Fromme, Lilja Yogui, Débora R. Alves, Mario Henrique Desbiez, Arnaud L.J. Langeheine, Marion Quagliatto, André Siebert, Ursula Brehm, Ralph PeerJ Conservation Biology BACKGROUND: The giant anteater belongs to the supraorder Xenarthra which occupies a systematically isolated position among placental mammals. The species is categorized as Vulnerable by the International Union for Conservation of Nature, and understanding its reproductive characteristics is critical for future conservation efforts. METHODS: Gross and microscopic anatomy of the genital organs of 23 male and 21 female adult and young roadkill giant anteaters in Brazil were studied. RESULTS: Male giant anteaters presented a short conical penis, intraabdominal testes, and prostate, vesicular and bulbourethral glands. A tubular remnant of the partially fused Müllerian ducts extended from the seminal colliculus through the prostate gland, continued cranially in the genital fold, bifurcated, and attached with one elongation each to the left and right epididymal corpus. The structure presented a total length of up to 10 cm and contained a yellowish liquid in its lumen. Histologically, the caudal section of this structure resembled the female vagina, the middle portion corresponded to the uterus, and the extensions showed characteristics of uterine tubes. In adult female giant anteaters, ovoid ovaries with occasional seminiferous cord-like structures were observed. The animals possessed a simple uterus, which was directly continuous with the vaginal canal. The caudal portion of the vagina had two lumina, separated by a longitudinal septum and opening into two apertures into the vaginal vestibule, cranial to the urethral opening. In the urethral and the lateral vestibular wall, glandular structures with characteristics of male prostate and bulbourethral glands, respectively, were found. The vestibule opened through a vertical vulvar cleft to the exterior. A pair of well-differentiated Wolffian ducts with a central lumen originated ventrally at the vaginal opening into the vestibule and passed in a cranial direction through the ventral vaginal and uterine wall. Each duct extended highly coiled along the ipsilateral uterine tube until the lateral pole of the ovaries where it merged with the rete ovarii. DISCUSSION: The reproductive morphology of giant anteaters reveals characteristics shared with other Xenarthrans: intraabdominal testes, a simple uterus, and a double caudal vagina. The persistence of well-differentiated genital ducts of the opposite sex in both males and females, however, singles them out among other species. These structures are the results of an aberration during fetal sexual differentiation and possess secretory functions. The possibility of a pathological degeneration of these organs should be considered in reproductive medicine of the species. CONCLUSION: Knowledge of the unique reproductive characteristics of the giant anteater is essential for future reproductive management of the species. Additionally, further research on the peculiarities of the persisting genital duct structures might help to understand sexual differentiation in placental mammals in general. PeerJ Inc. 2021-08-11 /pmc/articles/PMC8364315/ /pubmed/34447632 http://dx.doi.org/10.7717/peerj.11945 Text en ©2021 Fromme et al. https://creativecommons.org/licenses/by/4.0/This is an open access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited.
spellingShingle Conservation Biology
Fromme, Lilja
Yogui, Débora R.
Alves, Mario Henrique
Desbiez, Arnaud L.J.
Langeheine, Marion
Quagliatto, André
Siebert, Ursula
Brehm, Ralph
Morphology of the genital organs of male and female giant anteaters (Myrmecophaga tridactyla)
title Morphology of the genital organs of male and female giant anteaters (Myrmecophaga tridactyla)
title_full Morphology of the genital organs of male and female giant anteaters (Myrmecophaga tridactyla)
title_fullStr Morphology of the genital organs of male and female giant anteaters (Myrmecophaga tridactyla)
title_full_unstemmed Morphology of the genital organs of male and female giant anteaters (Myrmecophaga tridactyla)
title_short Morphology of the genital organs of male and female giant anteaters (Myrmecophaga tridactyla)
title_sort morphology of the genital organs of male and female giant anteaters (myrmecophaga tridactyla)
topic Conservation Biology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8364315/
https://www.ncbi.nlm.nih.gov/pubmed/34447632
http://dx.doi.org/10.7717/peerj.11945
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