The fine structure of the ductuli efferentes of the opossum

Abstract

The fine structure of the straight portions of the ductuli efferentes of the opossum were studied by light and electron microscopy. Two cell types, a ciliated and non-ciliated cell, characterize the simple columnar epithelium that lines the ductuli. The non-ciliated cell possesses an extraneous coating of the luminal plasmalemma, aggregations of apical canaliculi, and vacuoles of varying density distributed in the supranuclear cytoplasm. Such morphological criteria have been regarded as suggestive evidence for absorptive function. The epithelium rests upon a thick basement membrane beneath which are variable amounts of smooth muscle and connective tissue elements.Observations of the structure of the simple squamous epithelium lining the processus vaginalis are reported.Myelinated and unmyelinated nerves are found in the adnexa of the ductuli. These are enclosed in a thin, cellular investment, the innermost layer of which is usually incomplete. This cellular wrapper is considered a "perineural epithelium" but its characteristics are at variance with those found in the recent literature.

The Seminiferous Tubules in Dasyurid Marsupials

“…A single duct draining the testis was also found by Fraser in Metachirus opossum, Dasyurus viverrinus and in a Perameles 'embryo' and she considered that the rete testis in all polyprotodont marsupials was probably represented by a single duct which connected with a number of tubules of mesonephric origin in the epididymis. In Didelphis virginiana, van den Broek (1906), Chase (1939), and deBurlet (1921) report the occurrence of a single duct connecting the tubules with the epididymis, as in other polyprotodont marsupials, but in three specimens studied by Ladman (1967) from one to three ducts with the histological appear¬ ance of vasa efferentia were found. These apparently conflicting observations suggest that the urinogenital connection in this species may occur outside the body of the epididymis, and not within it, as suggested by Fraser. Multiple ducts of rete origin were found in Trichosurus vulpécula by Fraser (1919) and she suggested that this was the case in other diprotodont marsupials, including Phascolarctos.…”

Morfologia do escroto, do testículo e das vias espermáticas de Metachirus nudicaudatus (Geoffroy, 1803), Didelphidae-Marsupialia

“…O pedículo testículo-epididimário de M. nudicaudatus apresenta os componentes estruturais descritos por Ladman (1967) em D. virginiana, Nogueira et al (1977 e Nogueira (2012) em D. albiventris, Ribeiro (1981) em P. opossume Martinelli (1990) em M. cinérea. Semelhante ao observado por Martinelli (1990) em M. cinerea, M. nudicaudatus também não apresenta uma separação de vasos e dúctulo eferente em lobos distintos, ao contrário do observado por Rodger (1982) em D. albiventris.…”

“…Um único dúctulo eferente também foi descrito por Nogueira et al (1977), Ribeiro (1981), Rodger (1982), Tyndale-Biscoe & Renfree (1987), Woolley (1987) e Martinelli (1990) em marsupiais americanos e Woolley & Scarlet (1984), Tyndale-Biscoe & Renfree (1987) em marsupiais australianos. Embora alguns autores afirmem terem observado mais de um dúctulo unindo os dois órgãos em marsupiais americanos (Ladman 1967, Dawson et al 1988) e em marsupiais australianos (Tyndale-Biscoe & Refree 1987), essa observação parece ser improvável, uma vez que, como acontece em outros marsupiais , Ribeiro 1981, Rodger 1982, Woolley 1987, Martinelli 1990, esse dúctulo se ramifica próximo ao epidídimo, originando dúctulos de calibres menores que irão constituir a parte flexuosa do dúctulo eferente.…”

Microscopic anatomy of the scrotum, testis with its excurrent duct system and spermatic cord of <i>Didelphis azarae</i>

“…Ladman [1967] found one to three ducts in D. virginiana between the testis and the head of the epididymis. It is possible that these apparently conflicting observations may be explained by the fact that the preced ing authors had examined efferent ducts taken from different sites between the testis and the epididymis.…”