Evolution of the Vertebrate Epididymis

Jones, Russell C.

doi:10.1007/978-1-4615-0679-9_2

Cited by 75 publications

(101 citation statements)

References 134 publications

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“…Multiple reports on the epididymis typically recognize four different regions of the epididymis, the initial segment, caput, corpus, and cauda (Jones, 1998). However, no regional differences were observed along the length of the epididymis except for a gradual increase in size posteriorly which is similar to that described in Hemidactylus flaviviridis (Haider and Rai, 1981) and Tropidurus itambre (Ferreira et al, 2009; Table 2).…”

Section: Testicular Ducts In H Turcicussupporting

confidence: 53%

Proximal Testicular Ducts of the Mediterranean Gecko (Hemidactylus turcicus)

Rheubert

Sever

Geheber

et al. 2010

The Anatomical Record

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The efferent ducts of the Mediterranean Gecko, Hemidactylus turcicus (Gekkonidae) were investigated using light and electron microscopy. The seminiferous tubules unite into a single rete testis tubule. The rete testis divides into 3-4 ductuli efferentes which all drain into the cranial portion of the ductus epididymis. All efferent ducts are most active during the months of December to August. The rete testis is composed of a simple squamous epithelium with bifurcated nuclei and a labyrinthine network of intercellular canaliculi. Ciliated and nonciliated cells are present, and more than one cilium extends from the scattered ciliated cells. The presence of small clear vesicles and widened intercellular canaliculi suggest that cells of the rete testis are responsible for intake of luminal fluids. The ductuli efferentes are composed of a simple cuboidal epithelium consisting of ciliated and nonciliated cells, and ciliated cells are the dominant cell type. During the inactive season the number of lysosomes increases and the cells become spermiophagic. The ductus epididymis is composed of a tall pseudostratified columnar epithelium with relatively scarce basal cells. No evidence for regionalization was observed. The ductus epididymis is highly secretory during the active season with numerous electron-dense secretory granules, whose glycoprotein products are released by merocrine secretion. Basally, the active epididymis has swollen intercellular canaliculi and enlarged cisternae of rough endoplasmic reticulum. During the inactive season the secretory activity decreases and membranous structures and fibrous material are observed within widened intercellular canaliculi apical to the basal cells. Anat Rec, 293:2176Rec, 293: -2192

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Section: Testicular Ducts In H Turcicussupporting

confidence: 53%

Proximal Testicular Ducts of the Mediterranean Gecko (Hemidactylus turcicus)

Rheubert

Sever

Geheber

et al. 2010

The Anatomical Record

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“…Morphologically, the epididymis is divided into three segments: caput (proximal part), corpus, and cauda ( Fig. 1; Jones 1998). While the caudal epididymis acts as a sperm reservoir, the caput and corpus are responsible for sperm maturation (Moore 1998, Gatti et al 2004, Franca et al 2005, McLean 2005.…”

Section: Introductionmentioning

confidence: 99%

Identification and characterization of ERp29 in rat spermatozoa during epididymal transit

Guo¹,

Qü²,

Li³

et al. 2007

Reproduction

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The mammalian epididymis is able to create sequential changes in the composition of luminal fluid throughout its length, wherein spermatozoa undergo morphological, biochemical, and physiological modifications. Subsequently, spermatozoa acquire the ability for fertilization upon reaching the epididymal cauda. In this study, protein variations in Sprague-Dawley rat spermatozoa along the caput and caudal regions of epididymis were investigated by high-resolution two-dimensional gel electrophoresis (2DE) in combination with mass spectrometry. From total protein spots on the 2DE maps, 43 spots were shown to be significantly modified as sperm traverse the epididymis, and seven unambiguous proteins were identified from them. Finally, using indirect immunofluorescence, we demonstrated that localization of one of these seven proteins, the endoplasmic reticulum protein (ERp29) precursor, which was first reported in mammalian spermatozoa, was apparently up-regulated as the sperm underwent epididymal maturation and expressed mainly on caudal sperm. Western blot analysis also revealed that ERp29 precursor, from both whole spermatozoa and membrane proteins, increased significantly as the sperm underwent epididymal maturation. Furthermore, the results from immunofluorescence-stained epididymal frozen sections demonstrated that ERp29 was localized in cytoplasm of epididymal epithelia, and the fluorescence intensity was significantly higher in the caudal epididymis than in the caput. These clues indicated that the ERp29 precursor, perhaps related to secretory protein synthesis and absorbed by spermatozoa, may play a vital role in sperm maturation during the epididymal transit, particularly, in the sperm/organelle membrane. Reproduction (2007) 133 575-584

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“…It has been noted that daily sperm production is less than the number of spermatozoa in a normal ejaculate (Jones 1999), but this only explains the role of the epididymis in ensuring that mammals can ejaculate many more spermatozoa than are needed to achieve fertilisation. It has also been suggested that the unique functions of the mammalian epididymis are adaptations to enhance a male's chances of parenthood in competitive mating systems, that is, in sperm competition (Jones 1998;Jones et al 2007). Nevertheless, it is unlikely that sperm competition is very important in humans (Smith 1984a;Jones et al 2007) and, as many male infertility problems have been solved by procedures based on in vitro fertilisation (IVF) of the egg, there has been little recent interest in epididymal function.…”

Section: Sperm Maturation In the Epididymismentioning

confidence: 99%

“…However, the monotreme epididymis is unique among the mammals in being differentiated into only two distinctly different segments, including the characteristic 'initial segment', which is unique to mammals (Jones 1998). The initial segment has a tall actively secretory epithelium with long, coarse stereocilia, the presence of narrow (mitochondria-rich) cells and few spermatozoa in the lumen Jones 1981, 1982b).…”

Section: Division Of Labour Along the Epididymismentioning

confidence: 99%

Testicular descent, sperm maturation and capacitation. Lessons from our most distant relatives, the monotremes

Ecroyd

Nixon

Dacheux

et al. 2009

Reprod. Fertil. Dev.

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The present review examines whether monotremes may help to resolve three questions relating to sperm production in mammals: why the testes descend into a scrotum in most mammals, why spermatozoa are infertile when they leave the testes and require a period of maturation in the specific milieu provided by the epididymides, and why ejaculated spermatozoa cannot immediately fertilise an ovum until they undergo capacitation within the female reproductive tract. Comparisons of monotremes with other mammals indicate that there is a need for considerable work on monotremes. It is hypothesised that testicular descent should be related to epididymal differentiation. Spermatozoa and ova from both groups share many of the proteins that are thought to be involved in gamete interaction, and although epididymal sperm maturation is significant it is probably less complex in monotremes than in other mammals. However, the monotreme epididymis is unique in forming spermatozoa into bundles of 100 with greatly enhanced motility compared with individual spermatozoa. Bundle formation involves a highly organised interaction with epididymal proteins, and the bundles persist during incubation in vitro, except in specialised medium, in which spermatozoa separate after 3 h incubation. It is suggested that this represents an early form of capacitation. Abstract. The present review examines whether monotremes may help to resolve three questions relating to sperm production in mammals: why the testes descend into a scrotum in most mammals, why spermatozoa are infertile when they leave the testes and require a period of maturation in the specific milieu provided by the epididymides, and why ejaculated spermatozoa cannot immediately fertilise an ovum until they undergo capacitation within the female reproductive tract. Comparisons of monotremes with other mammals indicate that there is a need for considerable work on monotremes. It is hypothesised that testicular descent should be related to epididymal differentiation. Spermatozoa and ova from both groups share many of the proteins that are thought to be involved in gamete interaction, and although epididymal sperm maturation is significant it is probably less complex in monotremes than in other mammals. However, the monotreme epididymis is unique in forming spermatozoa into bundles of 100 with greatly enhanced motility compared with individual spermatozoa. Bundle formation involves a highly organised interaction with epididymal proteins, and the bundles persist during incubation in vitro, except in specialised medium, in which spermatozoa separate after 2-3 h incubation. It is suggested that this represents an early form of capacitation.

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Evolution of the Vertebrate Epididymis

Cited by 75 publications

References 134 publications

Proximal Testicular Ducts of the Mediterranean Gecko (Hemidactylus turcicus)

Proximal Testicular Ducts of the Mediterranean Gecko (Hemidactylus turcicus)

Identification and characterization of ERp29 in rat spermatozoa during epididymal transit

Testicular descent, sperm maturation and capacitation. Lessons from our most distant relatives, the monotremes

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