ISSN:0002-9106    

DOI:10.1002/aja.1001780402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractChanges in Leydig cell histology and testicular sudanophilic lipids were examined in relation to spermatogenic activity in the batMyotis lucifugus lucifugus(Chiroptera: Vespertilionidae) throughout the annual cycle in the northeastern United States. These changes were correlated with annual variations in plasma testosterone concentrations which have recently been described for this species. Gametogenic activity occurred during the months of May‐August when bats were metabolically most active. During hibernation (October‐April), when sperm are stored in the epididymides, and accessory glands are hypertrophic, the seminiferous tubules were at rest, and the germinal epithelium was reduced to reserve spermatogonia and Sertoli cells. Based on their structure and cyclic pattern of sudanophilic lipids, Leydig cells exhibited a pattern of activity that closely paralleled that of the seminiferous epithelium. On renewal of spermatogenesis in spring, Leydig cells became hypertrophied and accumulated lipid inclusions. These inclusions, seen as vacuoles in plastic sections and sudanophilic droplets in frozen sections, reched maximal accumulations in late June. In late July and during August, when peak testosterone levels occur in blood, lipid droplets were dramatically depleted, and Leydig cells were weakly sudanophilic. In September, when testosterone titers return to low baseline levels, Leydig cells had regressed but exhibited a marked increase in sudanophilic inclusions which appeared to be mostly lipofuscins. During the ensuing mating and hibernation periods, Leydig cells were involuted and filled with lipofuscins. During the periarousal period, however, Leydig cells became weakly Sudan‐positive while many large, intensely sudanophilic cells were scattered throughout the interstitium. In electron micrographs these cells were identified as macrophages. They appear to play an important role in the annual testicular cycle by phagocytizing the residues of Leydig cell involution in preparation for a new steroidogenic cycle. Seasonal changes in lipid inclusions were also observed in the seminiferous tubules. In addition, the relationship of the Leydig cell cycle to androgen action and the accessory organs in this bat is disc

ISSN:0002-9106    

DOI:10.1002/aja.1001780403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractPlasma membrane structure of bat spermatozoa was examined utilizing electron microscopy of thin sections and freeze‐fracture replicas. Notable membrane features observed in replicas from cauda epididymal spermatozoa included specialized particle aggregates at the junction between the acrosomal and postacrosomal region of the head (a membrane structure not previously described in mammalian spermatozoa) and another row of rod‐like particles just anterior to the posterior ring. Both of these specializations in fractured plasma membranes correspond with regions where the membrane is closely apposed to underlying structures when viewed in thin sections. The postacrosomal sheath appears to be composed of an array of longitudinally oriented filamentous components. Characteristic ordering of intramembranous particles was also noted in replicas from the midpiece region and the annulus. Major changes in plasma membrane structure were not seen in spermatozoa stored in the female reproductive tract; however, the appearance of linear particle aggregations in the principal piece membrane was noted. No evidence was obtained to suggest that an acrosome reaction had occurred in spermatozoa stored in fema

ISSN:0002-9106    

DOI:10.1002/aja.1001780404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractFemaleMyotis lucifugus lucifugus, obtained from a hibernaculum in northern central Ontario, were aroused during the week that normal departures from hibernation began, maintained in large cages at 28–30°C, and fed mealworms daily. Some bats ovulated less than 24 hr after arousal, and with one exception, all bats with normal, mature follicles ovulated within 72 hr. Histological examination of reproductive tracts from ovulated bats indicated that oviductal transit was completed in 24–48 hr, and that blastocyst formation and implantation occurred 4 and 10 days, respectively, after fertilization. These time intervals were somewhat shorter than those reported in previous studies; however, the differences appeared to be due to the relative accuracy in determining the time of ovulation, not to differences in rates of development among different populat

ISSN:0002-9106    

DOI:10.1002/aja.1001780405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractRhinopoma hardwickei hardwickeihas an annual reproductive cycle. Although many of the females become inseminated from the latter half of February until about the middle of April, ovulation has not been recorded until the 11th of March. A single follicle reached full development and released one ovum from either of the ovaries with nearly equal frequency, and a single conceptus was carried in the ipsilateral uterine cornu during each cycle. The embryo descended into the uterus as an early morula and attained the bilaminar blastocyst stage before undergoing implantation. As the morula advanced in age, the embryonic surface of the zona became progressively more basophilic. Hence in advanced morulae, the inner surface of the zona pellucida took a dark stain with hematoxylin and appeared like a distinct thin membrane, while the rest of the thickness of the zona was eosinophilic.Although progestational changes commenced in both uterine cornua, they became augmented in the uterine cornu on the side of ovulation and blastocyst attachment. After blastocyst attachment, the contralateral cornu reverted to an anestrus condition. The progestational changes became less conspicuous from the cranial to the caudal end of the uterus. Evidently, there was a linear gradient in the progestational response of the uterus with the cranial end being most responsive and the caudal end least responsive. The precise mechanism which brings this about is not known.

ISSN:0002-9106    

DOI:10.1002/aja.1001780406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe anatomy, biology, and chronology of reproduction in the male of the long penile form ofMormopterus planicepswas studied in southeast South Australia and Victoria. In the morphology of its primary and accessory reproductive organs,M. planicepswas generally reminiscent of other Molossidae; however, in the specialized (sebaceous) nature of the Cowper's gland ducts, in the presence of para‐anal glands, and in the unusual, horizontally bifid glans penis and the greatly elongated os penis, it was distinct from other Molossidae studied to date.Young of the year were not reproductively active. Adults displayed a single annual spermatogenic cycle that commenced in spring (September/October) and culminated in spermiogenesis in autumn (February‐May), during which period plasma levels of testosterone overtook androstenedione. Thereafter, spermatogenesis appeared to cease (though scattered sperm were seen in the seminiferous tubules until August), but abundant epididymal sperm reserves persisted until September/(October). The accessory glands were hypertrophied during this period, becoming involuted by October.Although the numbers of animals available for study were small, these observations, together with the appearance of spermatozoa in the ductus deferens in August/September suggested that mating could occur during the interval from autumn to spring. Late winter/spring insemination is normal for molossids from temperate environments. However, protracted spermatogenesis commencing in spring that is not accompanied by the availability of spermatozoa until autumn, and a subsequent apparent extension of fertility (epididymal sperm storage, accessory gland hypertrophy) beyond the testicular gametogenic phase, are aspects of the male reproductive cycle inM. planicepsthat have not heretofore been described in another molossid

ISSN:0002-9106    

DOI:10.1002/aja.1001780407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe reproductive biology of the female little mastiff bat (Mormopterus planiceps) was studied from specimens obtained throughout the year in southeast Australia, within the region occupied only by the long penile form of this species.Mormopterus planicepsappeared to undergo a single pregnancy each year and was monotocous. Conception occurred during late winter/early spring after a protracted proestrus, during which the uterine/vaginal epithelia attained an extraordinary thickness; spermatozoa were present in the uterine corpus, vagina, and intramural oviduct for at least 2 months prior to ovulation, although only those present in the oviducts were entire and thus appeared to be viable. Following ovulation, a massive postovulatory infiltration of phagocytes occurred; and the thickness of the uterine corpus epithelium was dramatically reduced. As in other molossids, the tract was bicornuate and dextrally functional.The length of gestation was difficult to determine because early embryonic stages, up to implantation, appeared to span several months (late July/August/September) as did parturition (December/January). Growth of the young was slow; nevertheless, females attained sexual maturity in their first year.Several unusual features included the presence of a long os clitoridis, and tubuloalveolar sudoriferous and associated lobulated, sebaceous, paravaginal glands, which surrounded and emptied into the lower vagina. A deep fornix anterior and lateral to the cervix probably serves to receive the secondary glans penis. The epithelium of the uterine corpus was stratified and indistinguishable, in its cytology and cyclicity, from that of the vagina; furthermore, it lacked a glandular endometrium. This portion of the female tract likely receives the elongated primary glans.These findings are discussed in relation to other Molossidae and to the reproductive biology of maleM. planiceps. Although the number of animals sampled was relatively small, the data suggest that this species does not exhibit the usual temperate molossid pattern of late winter/spring coincidence of spermatogenesis and ovulation. It would seem that pregnancy may begin, at least in some individuals, during the inhospitable winter months (when epididymal and uterine spermatozoa are abundant but spermatogenesis has largely terminated) and that additional conceptions continue into the early spring. The occurrence of sperm storage in both sexes of this species is unique among Molossidae studied to date.

ISSN:0002-9106    

DOI:10.1002/aja.1001780408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe chorioallantoic placenta ofMyotis lucifugusundergoes a transition from endotheliochorial to hemochorial. The original maternal endothelial basement membrane is incorporated into the apical portion of the syncytial trophoblast, where it persists until term. This intrasyncytial lamina is separated from the maternal blood by thin ectoplasmic projections of the syncytial trophoblast that project through the lamina and spread over the surface, completely engulfing it. While there appear to be direct channels, at junctions of the ectoplasmic processes, from the maternal blood to the intrasyncytial lamina, perfusion studies using the electron‐dense tracers alcian blue, ruthenium red, and Thorotrast show that these channels are physiologically closed. In contrast, lanthanum nitrate was able to gain access to the lamina via the extracellular channels. The endocytic uptake of the tracers was similar. These studies suggest several pathways for substances to cross the ectoplasmic zone and the intrasyncytial lamina. Substances may gain direct access to the lamina via extracellular channels, reach the lamina by vesicular transport, or bypass the lamina completely through fenestrations within the lamina. Autoradiographic studies show that the syncytial trophoblast synthesizes portions of the intrasyncytial lamina, demonstrating its partial fetal origin. How long the original maternal components persist and the functional significance of the intrasyncytial lamina are unknown. Possible functions of the lamina include increased surface area of the apical plasmalemma, selective filtration, structural support, and maintenance of cell polarit

ISSN:0002-9106    

DOI:10.1002/aja.1001780409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractStudies of bone from summer‐active little brown bats,Myotis lucifugus lucifugus, have demonstrated sex differences in the renewal of skeletal mineral reserves following spring‐arousal from hibernation. Patterns of bone remodeling in both sexes of bats indicate that new bone formation does not occur during hibernation: All new bone formation occurs during the summer‐active season. Results show that a short period of time elapses after hibernation before the initial demands of a large fetus and rapidly growing neonate are expressed on maternal skeletal reserves. Bone loss in summer‐active females was associated with pregnancy and lactation, whereas summer‐active males did not show evidence of bone loss but, instead, uninterrupted bone accretion throughout the summer‐active season. Osteoclasts and bone‐forming osteoblasts, absent during the hibernation period, reappeared on bone surfaces following spring‐arousal from hibernation. There was no apparent increase in osteoclast numbers or activity during lactation but resorption cavities were found in deep cortical lamellae distant from bone surfaces. The increase in bone resorption in lactating bats appeared to be by osteocytic osteolysis, suggesting that it might be a significant mechanism of bone/calcium regulation in this hibernating mammal thro

ISSN:0002-9106    

DOI:10.1002/aja.1001780410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractMorphological studies of thyroid C‐cells and morphometric analyses of parathyroid glands in summer‐active little brown bats indicated concomitant regulatory endocrine functions correlating with bone remodeling. C‐cells apparently maintain maximal activity throughout the summer‐active period in all bats. However, the hyperactivity of the parathyroid glands in summer‐active female bats can be correlated with the maintenance of plasma calcium concentrations during lactation, when the female skeleton undergoes a period of bone demineralization. In summer‐active male bats, which did not lose bone, the parathyroid glands did not show morphological evidence of hyperactivity; instead they were found to exhibit moderate parathyro

ISSN:0002-9106    

DOI:10.1002/aja.1001780411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY