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  • 1
    Electronic Resource
    Electronic Resource
    Late postnatal development and differentiation of the ductus epididymidis in a dasyurid marsupial (Antechinus stuartii) (1992)
    Springer
    Anatomy and embryology 186 (1992), S. 259-270 
    Details
    ISSN: 1432-0568
    Keywords: Epididymis ; Development ; Differentiation ; Marsupial ; Reproduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The general histology and ultrastructural features of the developing ductus epididymidis were examined in the brown marsupial mouse, Antechinus stuartii, from April, when males were sexually immature, until August, when the adult males were involved in mating activities, just prior to the annual male die-off. Samples were also examined 3 and 6 months after the August die-off period in males kept in isolation from conspecifics during the prebreeding and breeding periods. In April, tubule diameter and epithelial height were largest in the caput and least in caudal segments but the reverse was observed thereafter. Epithelial height increased in caput segments in August and remained high in the post die-off samples. However, caput epithelial height and tubule diameters were low compared with the remainder of the duct from July until February. Luminal shape in caudal segments (10, 11 and 12) changed in June from circular to a narrow slit, and the epithelium became variable in height. The epididymal epithelium was undifferentiated with few cytoplasmic organelles in April. Differentiation occurred mostly from May to June in associaion with an increased abundance of cytoplasmic organelles, increasing prostatic weight and rising plasma androgen levels. Differentiated principal and basal cells were found in caput and corpus regions in May and in caudal segments in June in association with the de novo development of a brush border of microvilli. Few clear cells were seen in caput and corpus regions of the duct in May but they, and mitochondria-rich cells, were common throughout the duct from June. Development of the unusual structural features of the cauda epididymidis preceded the arrival of spermatozoa in June. The presence of degenerating spermatozoa and cytoplasmic droplets in the cauda at this time suggested that it was not yet capable of supporting sperm viability. There was no evidence to suggest that the presence of spermatozoa has a stimulatory effect on the epididymis. Intact sperm were observed throughout the duct from July. Free cytoplasmic droplets, which showed some evidence of degeneration, collected in large masses in the distal corpus/ proximal cauda epididymidis of adult males between aggregates of spermatozoa. Epididymal differentiation appeared complete by mid-July; few ultrastructural changes occurred after this time. Recruitment of spermatozoa into the epididymis ceased by August and was associated with a rapid decline in sperm content in the proximal caput segments. In the November and February samples, spermatozoa were present only in distal corpus and proximal cauda segments. As in some eutherian mammals, differentiation of the epididymis in A. stuartii occurs in a descending fashion from caput to cauda. Development is linked to the onset of fluid and androgen production from the testis, which is essential for developing and maintaining a suitable caudal environment for storage and survival of spermatozoa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00174148
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  • 2
    Electronic Resource
    Electronic Resource
    Testicular and epididymal development in the brown marsupial mouse, Antechinus stuartii (Dasyuridae, Marsupialia) (1993)
    Springer
    Anatomy and embryology 188 (1993), S. 87-100 
    Details
    ISSN: 1432-0568
    Keywords: Marsupial ; Testis ; Epididymis ; Development ; Differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Reproductive tissues were collected monthly from male Antechinus stuartii during the first 5 months of post-partum development, a period corresponding to the time between birth and the initial increase in plasma androgen above non-detectable levels. The gonad appeared undifferentiated at day 3 after birth, but the basic structure of the testis (tunica albuginea, sex cords, stroma) was well established at 1 month of age. At this stage the developing sex cords contained a single layer of pre-Sertoli cells which surrounded a central core of gonocytes. Mitotic division of cells within the cords was common. Intertubular fetal Leydig cells, often observed in clumps, and perivascular and peritubular fetal Leydig cells were common and readily identified. By 2 months of age there was an obvious increase in cord diameter and the abundance of pre-Sertoli cells, while a marked reduction in the density of connective tissue cells and fetal Leydig cells was observed in the interstitium. Fetal Leydig cells appeared to persist only in close association with the developing seminiferous cords. Testicular size and the diameter and convolutions of the seminiferous cords increased substantially (two fold increase in cord diameter) by 3 months of age. Gonocytes had begun to migrate toward the basal lamina of the cords, and connective tissue cells and Leydig cells appeared in large numbers throughout the interstitium. By 4 and 5 months of age, gonocytes were commonly seen in contact with the basement membrane, and the cords remained non-patent. Leydig cell number and density increased greatly during these months. The epididymal epthelium remained undifferentiated throughout the first 5 months of development. Epithelial cells characteristically contained a large nucleus which occupied most of the cell, very little cytoplasm and few organelles. The diameter of the epididymal duct was similar throughout for the first 3 months of the study. In months 4 and 5 the diameter of the duct in caput and corpus regions increased, ahead of that of the cauda, possibly in relation to variations in androgen exposure at different regions along the developing duct. Further histological and quantitative studies on the growth and development of Leydig cells within the Dasyuridae are needed for comparision with eutherian mammals, which together with knowledge of the changing levels of fetal androgens may provide a greater understanding of the role of the different populations of Leydig cells in the differentiation of the testis and male reproductive tract. Marsupials from excellent animal models for such studies, since much of the early differentiation of the gonads and reproductive tract occurs in the pouch, rather than in utero, allowing easy access to young at this time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00191454
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  • 3
    Electronic Resource
    Electronic Resource
    Human pregnancy by in vitro fertilization (IVF) using sperm aspirated from the epididymis (1985)
    Springer
    Journal of assisted reproduction and genetics 2 (1985), S. 119-122 
    Details
    ISSN: 1573-7330
    Keywords: epididymis ; spermatozoa ; in vitro fertilization ; pregnancy ; sperm microaspiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Spermatozoa were collected by microaspiration from the corpus epididymidis of a 42-year-old man with secondary obstructive azoospermia and used for in vitro fertilization. At insemination 61% of the spermatozoa were motile, with a motility index of 157. One of five eggs was fertilized and this was subsequently transferred to the patient's wife at the two-cell stage. Ultrasound examination and changing hormone levels confirmed an ongoing pregnancy, which is currently at 30 weeks of gestation. This technique will provide a useful alternative for the management of some infertile men with obstructive azoospermia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01131497
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  • 4
    Electronic Resource
    Electronic Resource
    Structural features of the epididymis in a dasyurid marsupial (Antechinus stuartii) (1989)
    Springer
    Cell & tissue research 258 (1989), S. 203-210 
    Details
    ISSN: 1432-0878
    Keywords: Epididymis ; Histology ; Ultrastructure ; Antechinus stuartii (Marsupialia)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ductus epididymidis of the marsupial mouse Antechinus stuartii was divided into caput, corpus, and caudal regions using several constant morphological landmarks. Tubule diameter and epithelial height increased gradually from caput to cauda. In contrast, the surface area of the lumen of the ductus epididymidis increased to a maximum in the distal caput region, but decreased markedly in the distal cauda in association with characteristic changes in lumen shape (from circular to slit-shaped) and epithelial height. Epithelial cells of the ductus epididymidis were generally similar in structure to those described in other mammalian species. Principal and basal cells were common throughout the epithelium. Clear and mitochondria-rich cells were also identified, but occurred less frequently. Regional variations in cell ultrastructure were observed only in principal cells. Numerous vesicular inclusions occurred in the apical cytoplasm of cells in caput segments, membrane-bounded, electron-dense bodies were common in distal corpus regions, and a brush border of microvilli characterized the luminal surface of principal cells in caudal segments. Sperm index increased in the proximal caput, declined to basal levels in the distal caput and proximal corpus, and then increased to a maximum in segment 9 of the distal corpus and remained at about this level throughout the cauda epididymidis. Nuclear rotation, loss of cytoplasmic droplets, and other sperm maturational changes were observed along the epididymis. Discarded cytoplasmic droplets collected in large masses interspersed between aggregates of spermatozoa throughout the distal regions of the duct. There was no evidence of phagocytosis by principal cells of cytoplasmic droplets. The epididymis of A. stuartii differs from that of other mammals. The unusual caudal region, which has little storage capacity for sperm, is an unusual adaptation in a species in which the male is known to be polygamous.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223158
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  • 5
    Electronic Resource
    Electronic Resource
    Reproduction in the male honey possum (Tarsipes rostratus: Marsupialia): The epididymis (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 177 (1986), S. 385-401 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The epididymis of the adult honey possum, Tarsipes rostratus, is enclosed by a heavily pigmented tunica vaginalis and lies with the testis in a prominent prepenile scrotum. It is connected to the testis by a single ductus efferentis and is lined by approximately equal numbers of cuboidal ciliated and principal cells. It is unusual for marsupials in having no well-defined compartments or fibrous septae and in having extensive convolutions of the duct only at the caudal flexure. Three principal functional zones (initial, middle, and terminal segments) were identified in the epididymis, based on epithelial type and ultrastructural evidence of sperm maturation. Luminal diameter increases progressively throughout the tract, and epithelial height variations (from about 2 to 20 μm) are greatest in the terminal segment. The epithelium itself is remarkably low (maximum of 21.6 μm) compared with that seen in the epididymis of other mammals. The thickness of the peritubular smooth muscle coat increases close to the junction of the epididymis and ductus deferns. Sperm concentrations were estimated from counts of sperm nuclei and thus can be no more than approximations. The figures are consistent, however, with a rapid increase in concentration in the initial segment, indicating extensive fluid resorption. Sperm concentrations appear to peak in the distal zone of the terminal segment, although sampling problems and wide variations in count make such a conclusion only tentative. Principal and basal cells are the predominant cell types in the epididymal epithelium. Basal cells are most abundant in the initial and distal middle segment. Principal cells show structural evidence of active exchange with the luminal contents and have abundant apical stereocilia, the structure of which depends on the epididymal zone. Other cell types occur less commonly in the epithelium. Lipid-rich and phagocytic principal cells are restricted to the middle and distal zones of the middle segment, respectively. Clear cells, restricted to the terminal segment, and halo cells were found in very low numbers. As in some other marsupials, principal cells (possibly specialized for this function) selectively remove cytoplasmic droplets and probably other cellular debris from the luminal contents. In Tarsipes, however, this process is not very efficient, and many discarded droplets pass through to the terminal segment where they form large masses of debris associated with aggregates of degenerating spermatozoa.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001770308
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  • 6
    Electronic Resource
    Electronic Resource
    The features of sperm maturation in the epididymis of a marsupial, the brushtailed possum Trichosurus vulpecula (1976)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 147 (1976), S. 471-499 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Possum spermatozoa undergo a distinctive process of maturation in the epididymis, as shown by change in the properties of the sperm surface, by modification of their morphology and by their increasing capacity for progressive motility.Modification of the sperm surface over the head and tail is demonstrated by the different affinities of sperm from successive regions of the epididymis for FITC-conjugated wheat germ agglutinin and concanavalin A, and for cationic ferric oxide colloidal particles. Changes in sperm head morphology are caused by (1) a dramatic reshaping and consolidation of the acrosome in which excess plasma membrane overlying it is sloughed as a cluster of vesicles, (2) a reorientation of the nucleus almost parallel to the axis of the tail and (3) distal movement of the droplet from its initial envelopment of the nucleus to an eccentric position on the anterior segment of the midpiece.Spermatozoa released from the testis and caput epididymidis are essentially immotile or exhibit only lazy uncoordinated movements, whereas many from the corpus and most from the more distal regions of the epididymis display an energetic, progressive motility imparted by a rapid and stiff tail beat of narrow arc. This maturation of the capacity for motility is accompanied by an enhanced stability of the dense fibers and sheath, which become more resistant to the disruptive action of SDS and DTT, and by changes in the ultrastructure of the sperm tail. These include modification of the matrix of the mitochondria and also an unusual differentiation of the midpiece into two distinct segments. The anterior segment is defined by profuse peri-mitochondrial stacks of membranes which develop as spermatozoa pass through the epididymis. These membranes, although prominent in mature spermatozoa fixed in situ, appear sparse and disorganised in spermatozoa fixed after 15 to 30 minutes of active motility in physiological medium, suggesting their possible utilisation in motile spermatozoa. The posterior segment is characterised by a thick peri-mitochondrial cytoplasmic sleeve, by spirally arranged parallel fibrous bands immediately beneath the plasma membrane and, subsequently, as spermatozoa pass into the lower corpus epididymidis, by rows of flask-shaped surface invaginations which develop between the spiral bands.Despite broad similarities in the features of sperm maturation in this marsupial and in eutherian mammals, there are distinct differences in the structural organisation of their spermatozoa, particularly in the sperm head. Until more is known of the details of fertilisation in marsupials the significance of these differences will remain unclear.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001470407
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