Library

Notes: [Auszug] When uterine spermatozoa were collected 12 hr. after mating or insemination, using buffered, unbuffered balanced salt solutions, or a complicated synthetic culture medium such as T.C. 199, the motile life of these spermatozoa was always markedly prolonged if 5 per cent heated homologous serum had ...

Notes: [Auszug] WHEN washed free of seminal plasma or taken directly from the vas deferens or cauda epididymis, motile mammalian spermatozoa exhibit a marked tendency to agglutinate by the head region if suspended in homologous heated serum, or in isotonic media containing free electrolytes1. During examination of ...

Notes: [Auszug] Injection of rabbit spermatozoa into the uterus of rat has demonstrated a prolongation of the fertile life of the sperm, sometimes to almost twice that in the rabbit ...

Notes: Human spermatozoa display unusually limited affinities in their interaction with oocytes of other species. They adhered to and, when capacitated, penetrated the vestments of the oocyte of an ape-the gibbon, Hylobates lar- both in vivo and in vitro. On the other hand, human spermatozoa would not even attach to the zona surface of sub-hominoid primate (baboon, rhesus monkey, squirrel monkey), nor to the non-primate eutherian oocytes tested. Among the apes the gibbon stands furthest from man. Thus, although the specificity of human spermatozoa is not confined to man alone, it probably is restricted to the Hominoidea. This study also suggests that the evolution of man and perhaps the other hominids has been accompanied by a restrictive change in the nature of the sperm surface which has limited and made more specific the complementary surface to which their spermatozoa may adhere. For the failure of human spermatozoa to attach to the zona surface of all non-hominoid oocytes stands in contrast to the behaviour of spermatozoa of the several other mammals studied which, in most combinations, adhered readily to foreign oocytes, including those of man. Taxonomically, the demonstration of a compatibility between the gametes of man and gibbon, not shared with cercopithecids, constitutes further evidence for inclusion of the Hylobatidae within the Hominoidea.

Notes: Rat spermatozoa are highly dependent on the milieu of the normal epididymis for their maturation and survival, and die within a few days after androgenic support of the epididymal epithelium is withdrawn. The immediate changes in the ultrastructural organization of the epithelial cells of the rat epididymis, 2, 4, 6 and 14 days following castration have been monitored by morphometric analysis of localized regions of the caput and cauda epididymidis. While castration results in greater endocytosis by principal cells (Moore and Bedford, '79), many of their early structural changes following androgen withdrawal (disappearance of vesicles from the cell apex, reduction in rough endoplasmic reticulum, a drop in the volume of the Golgi cisternae and increase in lysosome content) seem indicative of inhibition of a secretory function. By contrast with the regressive response of the principal cell, the ultrastructure of clear cells in the cauda and of apical cells in the caput region appeared unchanged up to 14 days after castration. The implications of this evidence for specialized functions, and the suggestion of a differential androgen dependence among major cell types of the epididymal epithelium, are discussed briefly.

Notes: Horseradish peroxidase introduced into the lumen of the rat epididymis was taken up by the columnar cells of the epithelium by five minutes and more so after longer periods. The apical cells and particularly the clear cells in the caput and cauda epididymidis, respectively, showed significantly greater endocytotic activity than the principal cell in both locations. Within 14 days after castration, however, such differences in absorptive activity among the various cell types were essentially obscured because of increased endocytosis by the androgen-deficient principal cells. The results are discussed briefly in terms of the function of different epithelial cell types and secretory/absorptive activity in the epididymis.

Notes: In vitro fertilization techniques were used to analyze the penetrability of preovulatory hamster oocytes. The zonas of granulosa cell-free primary (GV) oocytes were penetrated in vitro in 2-3 h as readily as those of ovulated secondary oocytes (80% vs. 88%), whether inseminated separately or as mixed oocyte groups. In fact, a significantly higher (P〈0.05) mean number of perivitelline spermatozoa was present in immature (3.6) compared with secondary (1.9) oocytes, primarily reflecting a lack of the zona block to polyspermy in the immature population. By contrast, when granulosa cells remained around GV oocytes, zona penetration was low and more were penetrated, with more spermatozoa incorporated into the vitellus as a function of increasing time of oocyte recovery after hCG. We conclude, contrary to previous reports, that the zona pellucida of the hamster GV oocyte is readily penetrable by spermatozoa in vitro. However, the resumption of meiosis brings an increase in the penetrability of the granulosa cell vestment as well as the capacity for cortical granule exocytosis and the ability to decondense and transform the fertilizing sperm nucleus. The fact that the zona pellucida of the immature oocyte has proved to be penetrable in vitro and/or in vivo in all the mammals studied in this respect is discussed with particular reference to the situation in man.

Notes: In exploring the evolution and adaptive significance of epididymal function, we have studied the male excurrent duct and spermatozoa of a monotreme mammal - the echidna. Sperm maturation in the echidna excurrent duct appears simpler than that in most therians examined. Furthermore, neither the duct nor the spermatozoa of the echidna display specific therian characteristics; they bear a much closer resemblance to those of non-passerine birds.The echidna spermatozoon is filiform, the sperm tail has no distinctive features, and the anterior seventh of the undulating nucleus is covered by a modest acrosome. Immediately behind this a restricted apposition between plasma membrane and nuclear envelope constitutes a post-acrosomal ring. This is evident also in some reptiles and marsupials, whereas in Eutheria such a membrane association appears as the posterior ring at the base of the sperm nucleus.Maturation of spermatozoa in the Wolffian duct of the echidna appears to be expressed only in a changing capacity for motility and in loss of the cytoplasmic droplet. Neither surface, structural nor acrosomal changes that characterize sperm maturation in therian mammals have been detected in maturing echidna spermatozoa. The echidna duct displays little of the regional complexity of the epithelium that typifies this duct in the Theria. Of five regions distinguishable on the basis of epithelial morphology, the first two appear to be counterparts of efferent ducts by virtue of a low columnar, partially ciliated epithelium. The tall pseudo-stratified Golgi-rich epithelium of the major portion of the duct broadly resembles that of the therian epididymis, but it displays only two structurally distinguishable regions, the more distal being the site of a dense luminal secretion. The foamy epithelial cells of the fifth and terminal region, characterized by a mass of supra-nuclear vesicles and rough ER, suggest a secretory function that may in some way contribute significantly to the ejaculate, for accessory glands are poorly developed in monotremes.Maturation of spermatozoa in the Wolffian duct of the echidna appears to be expressed only in a changing capacity for motility and in loss of the cytoplasmic droplet. Neither surface, structural nor acrosomal changes that characterize sperm maturation in therian mammals have been detected in maturing echidna spermatozoa. The echidna duct displays little of the regional complexity of the epithelium that typifies this duct in the Theria. Of five regions distinguishable on the basis of epithelial morphology, the first two appear to be counterparts of efferent ducts by virtue of a low columnar, partially ciliated epithelium. The tall pseudo-stratified Golgi-rich epithelium of the major portion of the duct broadly resembles that of the therian epididymis, but it displays only two structurally distinguishable regions, the more distal being the site of a dense luminal secretion. The foamy epithelial cells of the fifth and terminal region, characterized by a mass of supra-nuclear vesicles and rough ER, suggest a secretory function that may in some way contribute significantly to the ejaculate, for accessory glands are poorly developed in monotremes.The possibility is considered that the relative complexity of epididymal function and sperm structure in therian mammals could have been determined by evolutionary change in the milieu of the female tract, and/or in the character of the egg vestments that the fertilizing spermatozoon must penetrate.

Notes: Spermatozoa have been observed with the electron microscope at various stages of their approach to and penetration of the rabbit ovum. No significant change in fine structure is observed in uterine sperm, or in many of the sperm at the periphery of the granulosa investment around the ovum. By contrast, a majority of sperm lying between the granulosa cells or on the surface of the zona pellucida display various stages of the “acrosome reaction”; this involves fusion and vesicle formation between the plasma membrane and the outer membrane of the acrosome. Loss of these vesicular elements, and content of the acrosome cap, takes place before sperm begin to penetrate the substance of the zona. The constricted posterior “equatorial” segment of the acrosome cap does not take part in the acrosome reaction and remains with its content intact during penetration of the zona; neither does the content of the apical sub-acrosomal region (perforatorium) or post-acrosomal region appear to change in traversing the zona. The hypothetical zona lysin is thus presumed to be closely associated with the persistent inner membrane of the acrosome, which now becomes the limiting membrane around the anterior part of the sperm nucleus.No “penetration filament” has been observed, but sperm within the zona pellucida of ageing eggs are often preceded by a straight or curved fissure in the substance of the zona. The possible nature of capacitation and its relation to the acrosome reaction and to the process of penetration, are discussed briefly.

Notes: The ultrastructure of fertilization has been studied in rabbit eggs recovered 11 to 15 hours after natural mating. Many sperm passing between the granulosa cells had undergone the acrosomal reaction, but this was not invariable, and, occasionally, intact sperm were present close to the zona pellucida. The cells of the corona radiata sometimes develop pseudopodial processes at the abovular surface and can ingest sperm after natural mating. The bulk of the content of the acrosome and the vesiculated elements formed during the acrosomal reaction, are lost before the sperm penetrates the zona pellucida, at which point the naked inner membrane of the acrosome is brought into intimate apposition with the zona. As the sperm cleaves a path through the zona pellucida, the posterior equatorial segment of the acrosome remains intact, and later persists as such in perivitelline sperm and quite possibly after incorporation of the sperm head into the vitellus.Sperm head entry into the vitellus is a two-fold process. The fertilizing sperm invariably fuses first with the vitelline membrane over the midposterior region of the head, whereas the rostral or acrosomal portion is drawn into the vitellus while encased by a flattened vesicle; this vesicle is comprised by the persistent inner membrane of the acrosome and externally by vitelline membrane sequestered from the egg surface. Soon after exposure to ooplasm, the sperm nucleus begins to decondense at a variable rate into a web of electron-dense strands; this process begins in the midposterior region, and then extends rostrally and caudally. At the same time the encasing membranes are reflected away from the anterior region of the nucleus, exposing subacrosomal material to the ooplasm. At this point the perforatorium remains, but this and the associated membranes are presumed to disintegrate eventually within the egg. After decondensation of the nucleus is complete, the faintly staining chromatin becomes enveloped by a series of compressed vesicles which together will form the porous limiting membrane of the male pronucleus.The last region to be incorporated is the sperm tail, the plasma membrane of which is lost as organelles of the tail pass into the ooplasm. During its incorporation, the midpiece engenders some reaction at the egg surface, and the mainpiece sometimes becomes fused with surface processes before it enters the body of the egg. The midpiece then commonly disintegrates, with dispersion of the mitochondrial sheath, whereas the mainpiece usually remains essentially intact until the time of syngamy or beyond.