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J J Rasweiler

Publications and source records attributed to J J Rasweiler.

36 records · Page 2Linked to original sources
PubMed1988

Ovarian function in the captive black mastiff bat, Molossus ater.

In nearly all animals from a laboratory breeding colony that were examined (85/86) the right ovary was significantly larger than the left. Although primordial follicles were present in both ovaries, Graafian follicles and CL were noted only in the right ovary. The left ovary usually had a much less prominent intraovarian vascular supply, and it is suggested that this may play a central role in limiting the ability of follicles to grow on that side. Many of the bats examined very soon after the introduction of stud males had well-developed CL, sometimes of 2-3 different ages, and uteri that had probably been subjected to stimulation by luteal hormones. Such observations made on females that had been housed with a stud male only for 24 h indicate that the black mastiff bat is a spontaneous ovulator with a functional luteal phase. It was common to observe an extended period after the introduction of a stud male during which spermatozoa were present in the vaginal smears from a female almost every day. Most of the ovulations that resulted in pregnancies appear to have occurred during this period. Of the 72 bats with CL, 11 possessed 2 or more CL of the same age, indicating that multiple ovulations can sometimes take place. The right ovaries of all females examined during advanced pregnancy had non-atretic, vesicular or Graafian follicles in addition to the CL of pregnancy.

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PubMed1987

Prolonged receptivity to the male and the fate of spermatozoa in the female black mastiff bat, Molossus ater.

Observations were made on the reproductive biology of black mastiff bats maintained in a laboratory colony. Many of the females were inseminated within 24 h after the introduction of the males, and most exhibited a period of 10-50 days during which spermatozoa were present in their vaginal smears almost every day. The frequency of sperm-positive smears began to fall off around the time of implantation, but some smears taken much later in pregnancy were positive. The extent to which spermatozoa in the smears came from reservoirs in the female tract could not be thoroughly investigated, but evidence was obtained that the females have more than a limited period of oestrus. Female courtship behaviour and new copulations were sometimes observed many days after the start of the breeding activity. Also, histological studies of the reproductive tracts of females which had recently mated revealed that many were not in a periovulatory condition. Intact spermatozoa were usually found in the uterine horns and distal oviducts of preovulatory bats and those carrying tubal ova. Spermatozoa were absent from the oviducts of animals bearing early uterine embryos, and were much less abundant in the uterine horns after the start of implantation. Many of the excess spermatozoa appeared to have been expelled into the upper cervix where phagocytic leucocytes were commonly observed in the lumen. Some sperm components were also taken up by epithelial cells in the oviducts and uterine horns.

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PubMed1984

Reproductive failure due to the entrapment of oocytes in luteinized follicles of the little bulldog bat (Noctilio albiventris).

The reproductive tracts of 112 female little bulldog bats collected around the onset of a breeding season in the Cauca Valley of Colombia were examined histologically. Of the 88 females with luteinizing/luteinized follicles or new CL, 72 carried tubal ova or uterine blastocysts and 16 were non-pregnant. In 14 of the latter follicle rupture had apparently failed to occur, and the oocyte or a collapsed zona pellucida was found within a luteinizing or luteinized follicle. These structures appeared to be functional because most of the affected bats demonstrated preferential stimulation of the ipsilateral oviduct and/or uterine horn. Two of these animals also had a second, older luteinized follicle which contained the remnants of an oocyte. None of these 14 bats exhibited the uterine modifications thought to be associated with a previous pregnancy or had prominent mammary glands. Such reproductive features were, in contrast, frequently demonstrated by other females in the population. These observations suggest that the luteinization of unruptured follicles may have occurred in prepubertal members of the population and reflect immaturity of the hypothalamo-pituitary -ovarian axis in these individuals.

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PubMed1979

Differential transport of embryos and degenerating ova by the oviducts of the long-tongued bat, Glossophaga soricina.

Female long-tongued bats which had been maintained in sexually segregated groups in captivity for more than 8 months were bred and killed at various intervals between Days 1 and 25 post coitum. Their reproductive tracts were then examined histologically. In 20 of the 28 bats carrying tubal embryos the remnants of 1-4 other ova were also observed in the oviductal ampullae. These remnants consisted of intact zonae pellucidae containing cellular debris, empty zonae, and/or zona fragments. Since long-tongued bats are monovular, the remnants had apparently been retained in the oviducts from previous, non-fertile reproductive cycles. In 27 of the 31 bats carrying implanting blastocysts, zonae pellucidae probably shed by the embryos had been retained in the oviducts. The remnants of 1-3 ova were also observed in the oviductal ampullae of 22 of the 31 bats carrying uterine blastocysts. In at least 14 of these bats the embryos had by-passed ovum remnants in the oviducts on their way to the uterus. No evidence of such remnants was found in the oviducts of 17 animals with tubal or uterine embryos, although old, as well as new, CL were present in the ovaries.

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PubMed1977

Preimplantation development, fate of the zona pellucida, and observations on the glycogen-rich oviduct of the little bulldog bat, Noctilio albiventris.

The reproductive biology of Noctilio albiventris was investigated histologically in 112 females collected at the start of their synchronized breeding season during two different sampling years in the Cauca Valley of Colombia. Both ovaries were functional, but the animals were generally observed to be monovular. Embryonic development in the oviduct was found to proceed to blastocyst formation and loss of the zona pellucida. In 22 animals the discarded zona had been left behind in the oviduct upon passage of the embryo into the uterus and was still undissolved at the time of amniogenesis, the latest stage examined. The zonae which had passed into the uterus with the embryos often exhibited signs of dissolution. Most of the early blastocyts were morphologically distinctive, lacking a typical inner cell mass and being instead largely bilaminar. Degenerating ova from previous ovulations were found in the oviducts of two pregnant bats, suggesting that Noctilio may be another species in which the embryo stimulates its own escape from the oviduct. During tubal passage of the embryo the secretory cells of the oviductal ampulla and isthmus exhibited a transient engorgement with glycogen, particularly on the side ipsilateral to the new corpus luteum.

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PubMedDate not supplied

The interhaemal barrier in the chorioallantoic placenta of the greater mustache bat, Pteronotus parnellii, with observations on amplification of its intrasyncytial lamina.

Chorioallantoic placentae were obtained from a reproductively synchronized wild population of greater mustache bats for ultrastructural and immunocytochemical examination. The single discoidal placenta was always located in a lateral to mesometrial position on the right side of the uterus, which in the non-pregnant state is partially bicornuate. The placenta was labyrinthine and haemodichorial in advanced pregnancy. The interhaemal barrier included syncytiotrophoblast that lined the maternal vascular spaces and an underlying, continuous layer of cytotrophoblast. The barrier also contained a discontinuous extracellular layer, the intrasyncytial lamina, that was usually completely surrounded by syncytiotrophoblast. Two lines of evidence suggest that the intrasyncytial lamina may serve, in part, to strengthen the interhaemal barrier: (1) the lamina became significantly thicker as the maternal vascular channels became larger; and (2) the syncytiotrophoblast in the walls of the smallest vascular tubules expressed only very limited amounts of cytokeratins, normally a major component of the cytoskeleton of cells of epithelial origin, while the cytokeratin-rich cytotrophoblast was often highly attenuated. It was not uncommon to see gaps between the ectoplasmic processes of syncytiotrophoblast which exposed portions of the intrasyncytial lamina to the maternal vascular space. As platelet adhesion was never observed in such areas, the intrasyncytial lamina may be augmented in part by material that is non-thrombogenic.

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PubMedDate not supplied

Relationships between orientation of the blastocyst during implantation, position of the chorioallantoic placenta, and vascularization of the uterus in the noctilionoid bats Carollia perspicillata and Noctilio sp.

In most eutherian mammals, the inner cell mass (ICM) of the blastocyst assumes an almost constantly specific orientation to the uterus at the time of implantation, and this is usually correlated with subsequent positioning of the fetal membranes and chorioallantoic placenta. Although these relationships tend to be conserved between closely related species, this is not the case in the noctilionoid bats. In Carollia perspicillata, which has a simplex uterus, the ICM of the single blastocyst becomes oriented towards the uterotubal junction on the side of ovulation, and the discoidal placenta develops in a fundic position. In Noctilio sp., which have partially bicornuate uteri, the ICM becomes oriented instead towards an endometrial ridge that runs along the antimesometrial to lateral side of the gravid horn. As development proceeds, however, the blastocyst rotates almost 180 degrees, and the discoidal placenta eventually assumes a mesometrial to lateral position. In these species, implantation and subsequent development of the discoidal placenta clearly seem to be targeting major maternal vessels supplying the uterus, rather than exhibiting a consistent pattern of orientation relative to its mesenteric attachments. This permits their chorioallantoic placentae to develop a dual maternal blood supply that may be essential for the development of relatively large, precocious infants.

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