Observaciones anatómicas e histológicas del sistema reproductor masculino y femenino en Tamandua tetradactyla (Myrmecophagidae: Xenarthra) Translated title: Anatomical and histological observations of the reproductive tract in males and females of Tamandua tetradactyla (Myrmecophagidae: Xenarthra)

Abstract

El oso melero (Tamandua tetradactyla) pertenece a la familia Myrmecophagidae del superorden Xenarthra. La fragmentación del hábitat, la caza local y el mascotismo, lo ubican en la categorización "potencialmente vulnerable" en Argentina. Para la aplicación a futuro de protocolos de biotecnología reproductiva en programas de manejo y conservación de gametos se realizaron disecciones anatómicas, estudios histológicos y de morfometría espermática (mediante microscopia óptica y electrónica) en tractos reproductores de 5 hembras y 4 machos. La diferenciación de la genitalia externa entre sexos resulta dificultosa: las hembras presentan una hendidura longitudinal y los machos presentan un orificio terminal en la punta del pene. El pene, contiguo al ano, está formado mayormente por tejido conectivo denso, el cuerpo esponjoso esta menos desarrollado en su parte superior y el extremo distal no forma un glande. Los testículos están ubicados internamente en la cavidad pélvica unidos por una capa del peritoneo visceral. Los ovarios presentan una serosa de epitelio simple cúbico y zona medular rodeada por la corteza. El útero es simple y dorso-ventralmente aplanado. Los estudios histológicos evidenciaron un seno urogenital en vez de una verdadera vagina, el cérvix fue elongado y fue denominado canal utero-vaginal. Entre este último y el seno urogenital, todas las hembras presentaron un tabique membranoso biperforado semejante a un himen.

Translated abstract

To the Xenarthra superorder belongs the anteater (Tamandua tetradactyla) member of the Myrmecophagidae family. Because of the habitat fragmentation, local hunting and their usage as a pet, it' s has been categorized as "potentially vulnerable" in Argentina. Anatomical dissections and morphometric studies were performed; histological and sperm morphometric were made by light and electron microscopy in reproductive tract of 5 females and 4 males. Differentiation of the external genitalia, between sexes, is difficult: females had a slit of the vulva occupying the entire body, while males had a terminal orifice near the tip of the penis. The conical penis is located adjacent to the anus and is composed mostly of dense connective tissue, the corpus spongiosum was less developed in its upper part and the distal end was not forming a glans. The testicles are located internally in the pelvic cavity and connected by a layer of visceral peritoneum. The ovaries were covered by a simple cubic epithelium and present a medulla surrounded by the cortex. The uterus was simple, pear-shaped and dorsoventrally flattened. Histological studies showed an urogenital sinus instead of a real vagina, the cervix was elongated and was called utero-vaginal canal. Between the cervix and the urogenital sinus all females showed a biperforated membranous septum, similar to an hymen