The development of a testosterone stimulation test in the Virginia opossum (Didelphis virginiana) and its use in evaluating deslorelin contraception

2008 ◽  
Vol 20 (5) ◽  
pp. 563 ◽  
Author(s):  
S. D. Johnston ◽  
F. C. Camacho ◽  
L. Carrillo ◽  
N. Guy ◽  
J. Govea ◽  
...  
Keyword(s):  
Cell Types ◽  
Didelphis Virginiana ◽  
Stimulation Test ◽  
Plasma Testosterone ◽  
Sperm Production ◽  
Testosterone Secretion ◽  
Gonadotrophin Releasing Hormone ◽  
Testicular Histology ◽  
Virginia Opossum ◽  
And Control

The aims of the present study were to examine the variability of testosterone secretion in the Virginia Opossum over a 24 h period and to develop a testosterone stimulation test that would provide an index of the prevailing testosterone biosynthetic capacity of the testes; the latter was used to clinically evaluate the efficacy of a gonadotrophin-releasing hormone agonist contraceptive. Sexually-mature captive opossums (n = 12) located in Africam Safari (Mexico) sampled every 12 h over 24 h consistently showed basal (<0.21 ng mL–1) blood testosterone concentrations. Intra-muscular injection of buserelin (2 μg mL–1) and human chorionic gonadotrophin (hCG; 1000 IU) resulted in an increase (P < 0.05) of plasma testosterone concentrations with maximal concentrations (3.9 ng mL–1 and 5.8 ng mL–1 respectively) occurring 120 min after injection. Plasma testosterone declined relatively rapidly to basal concentrations after 240 min with hCG but remained elevated after the same period of time with buserelin. Male opossums treated with (n = 6) and without (n = 6) a controlled-release deslorelin implant (Suprelorin; 4.7 mg deslorelin) were evaluated over a 10-week period for changes in testosterone secretion (hCG stimulation test) and sperm production (spermatorrhea). At the end of this period, the animals were hemi-castrated and their relative testicular quantitative histology compared. Testosterone concentration decreased over the course of the study in both treated and control animals (P < 0.0001) but there was no apparent effect of deslorelin on testosterone secretion, testicular histology (relative proportions of testicular cell types and seminiferous tubule diameter), or sperm production (presence of sperm in the cauda epididymis or urine)

Why so many mammalian spermatozoa - a clue from marsupials?

1984 ◽  
Vol 221 (1223) ◽  
pp. 221-233 ◽  
Keyword(s):  
Didelphis Virginiana ◽  
High Survival ◽  
High Survival Rate ◽  
Sperm Production ◽  
Australian Family ◽  
Cauda Epididymidis ◽  
Virginia Opossum ◽  
Shed Light ◽  
Mammalian Spermatozoa ◽  
Made In

Mammals generally ejaculate many more spermatozoa than seem to be needed for fertilization. This apparent profligacy has not been explained, but observations made in marsupials may shed light on it. The Virginia opossum, Didelphis virginiana , inseminates only about three million spermatozoa, a very low number. As a corollary, relatively few ( ca . 13 x 10 6 ) are stored in each cauda epididymidis. However, some 5% of the spermatozoa that the opossum ejaculates populate the oviduct about 12 h later when ovulation can be anticipated - a success rate in the female orders of magnitude greater than in eutherian mammals. I t is not certain what determines the unusually efficient transport to and the high survival rate of spermatozoa in the oviduct of Didelphis , but two unusual features suggest themselves as possible contributors. Didelphis (and all other American marsupial) spermatozoa undergo a head-to-head pairing in the epididymis by the acrosomal face; this serves to isolate the acrosome of ejaculated spermatozoa from the female milieu until the pairs separate in the oviduct. Secondly, spermatozoa are housed in special crypts in the isthmus of the oviduct. Australian marsupials, which usually lack such features, store spermatozoa in the epididymis in numbers more close to those in comparably sized eutheriam mammals. Exceptions which store very low sperm numbers there can be seen in one Australian Family, the Dasyuridae. The spermatozoa of dasyurids are not paired, but the species examined possess distinctive sperm storage crypts in the oviducal isthmus similar to those in the opossum. The present findings suggest that where mechanisms exist that could protect the acrosome and, or, the whole spermatozoon in the female tract, a much lower level of sperm production can be maintained without compromising fertility. While the number ejaculated typically by any one species is probably determined ultimately by several interacting factors, it therefore seems likely that a most important one in this respect relates to conditions spermatozoa face in the female tract.

scholarly journals Experimental Aerosol Inoculation and Investigation of Potential Lateral Transmission ofMycobacterium bovisin Virginia Opossum (Didelphis virginiana)

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Karla A. Fenton ◽  
Scott D. Fitzgerald ◽  
Steve Bolin ◽  
John Kaneene ◽  
James Sikarskie ◽  
...  
Keyword(s):  
Rapid Test ◽  
Didelphis Virginiana ◽  
Control Groups ◽  
Endemic Focus ◽  
Test Culture ◽  
Virginia Opossum ◽  
And Control ◽  
Lateral Transmission ◽  
Antibody Tests ◽  
Culture Positive

An endemic focus ofMycobacterium bovis(M. bovis) infection in the state of Michigan has contributed to a regional persistence in the animal population. The objective of this study was to determine if Virginia opossums (Didelphis virginiana) contribute to disease persistence by experimentally assessing intraspecies lateral transmission. One wild caught pregnant female opossum bearing 11 joeys (young opossum) and one age-matched joey were obtained for the study. Four joeys were aerosol inoculated withM. bovis(inoculated), four joeys were noninoculated (exposed), and four joeys plus the dam were controls. Four replicate groups of one inoculated and one exposed joey were housed together for 45 days commencing 7 days after experimental inoculation. At day 84 opossums were sacrificed. All four inoculated opossums had a positive test band via rapid test, culture positive, and gross/histologic lesions consistent with caseogranulomatous pneumonia. The exposed and control groups were unremarkable on gross, histology, rapid test, and culture. In conclusion,M. bovisinfection within the inoculated opossums was confirmed by gross pathology, histopathology, bacterial culture, and antibody tests. However,M. boviswas not detected in the control and exposed opossums. There was no appreciable lateral transmission ofM. bovisafter aerosol inoculation and 45 days of cohabitation between infected and uninfected opossums.

Testosterone secretion, testicular histology and the cryopreservation of cauda epididymidal spermatozoa in the common ringtail possum (Pseudocheirus peregrinus)

2008 ◽  
Vol 20 (3) ◽  
pp. 391 ◽  
Author(s):  
D. J. Phillips ◽  
A. McKinnon ◽  
T. Keeley ◽  
S. D. Johnston
Keyword(s):  
Egg Yolk ◽  
Peripheral Circulation ◽  
Plasma Testosterone ◽  
Pseudocheirus Peregrinus ◽  
Gonadotrophin Releasing Hormone ◽  
The Common ◽  
Testicular Histology ◽  
First Time ◽  
Ringtail Possum ◽  
Motility Rate

The present study reports novel aspects of the reproductive biology of the male common ringtail possum (Pseudocheirus peregrinus). Plasma testosterone was measured through a stimulation test using the gonadotrophin-releasing hormone agonist, buserelin. Following intra-muscular administration of buserelin, there was an increase (P < 0.05) in testosterone concentration in the peripheral circulation 4 h later. Quantitative testicular histology of this species was described for the first time. Eight stages of the seminiferous epithelium cycle were identified in 10 possums and their relative frequency determined. Spermatozoa were recovered from the cauda epididymides of hemi-castrated possums and cryopreservation conducted in straws (6°C min–1) using final glycerol concentrations ranging between 2 and 20% in Tris-citrate egg yolk extender (v/v). Frozen straws were thawed and post-thaw motility, rate of motility, the percentage of live–dead spermatozoa and the percentage of sperm with swollen decondensed nuclei recorded. Similar to other marsupial sperm, common ringtail possum cauda epididymidal spermatozoa required high levels of glycerol (10–16%) in order to maintain post-thaw viability.

scholarly journals Modelling the Human Placental Interface In Vitro—A Review

Micromachines ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 884
Author(s):  
Marta Cherubini ◽  
Scott Erickson ◽  
Kristina Haase
Keyword(s):  
Drug Testing ◽  
Cell Types ◽  
In Vitro Models ◽  
Placental Development ◽  
Scientific Challenge ◽  
Induced Pluripotent ◽  
And Function ◽  
And Control

Acting as the primary link between mother and fetus, the placenta is involved in regulating nutrient, oxygen, and waste exchange; thus, healthy placental development is crucial for a successful pregnancy. In line with the increasing demands of the fetus, the placenta evolves throughout pregnancy, making it a particularly difficult organ to study. Research into placental development and dysfunction poses a unique scientific challenge due to ethical constraints and the differences in morphology and function that exist between species. Recently, there have been increased efforts towards generating in vitro models of the human placenta. Advancements in the differentiation of human induced pluripotent stem cells (hiPSCs), microfluidics, and bioprinting have each contributed to the development of new models, which can be designed to closely match physiological in vivo conditions. By including relevant placental cell types and control over the microenvironment, these new in vitro models promise to reveal clues to the pathogenesis of placental dysfunction and facilitate drug testing across the maternal–fetal interface. In this minireview, we aim to highlight current in vitro placental models and their applications in the study of disease and discuss future avenues for these in vitro models.

scholarly journals Integrated Patterning Programs During Drosophila Development Generate the Diversity of Neurons and Control Their Mature Properties

2021 ◽  
Vol 44 (1) ◽  
Author(s):  
Anthony M. Rossi ◽  
Shadi Jafari ◽  
Claude Desplan
Keyword(s):  
Stem Cells ◽  
Nervous System ◽  
Neural Stem Cells ◽  
Cell Types ◽  
Annual Review ◽  
Publication Date ◽  
Temporal Patterning ◽  
Long Time ◽  
Neuronal Types ◽  
And Control

During the approximately 5 days of Drosophila neurogenesis (late embryogenesis to the beginning of pupation), a limited number of neural stem cells produce approximately 200,000 neurons comprising hundreds of cell types. To build a functional nervous system, neuronal types need to be produced in the proper places, appropriate numbers, and correct times. We discuss how neural stem cells (neuroblasts) obtain so-called area codes for their positions in the nervous system (spatial patterning) and how they keep time to sequentially produce neurons with unique fates (temporal patterning). We focus on specific examples that demonstrate how a relatively simple patterning system (Notch) can be used reiteratively to generate different neuronal types. We also speculate on how different modes of temporal patterning that operate over short versus long time periods might be linked. We end by discussing how specification programs are integrated and lead to the terminal features of different neuronal types. Expected final online publication date for the Annual Review of Neuroscience, Volume 44 is July 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

scholarly journals Field test of a single-injection gonadotrophin-releasing hormone immunocontraceptive vaccine in female white-tailed deer

2009 ◽  
Vol 36 (3) ◽  
pp. 177 ◽  
Author(s):  
James P. Gionfriddo ◽  
John D. Eisemann ◽  
Kevin J. Sullivan ◽  
Ronald S. Healey ◽  
Lowell A. Miller ◽  
...  
Keyword(s):  
Effective Means ◽  
First Year ◽  
Management Tools ◽  
Releasing Hormone ◽  
Adverse Health Effects ◽  
Contraceptive Agents ◽  
Silver Spring ◽  
Gonadotrophin Releasing Hormone ◽  
And Control ◽  
Immunocontraceptive Vaccine

The development and use of safe, effective and practical wildlife contraceptive agents could reduce reproduction in locally overabundant deer populations in situations where traditional management tools such as regulated hunting cannot be employed. GonaCon Immunocontraceptive Vaccine (the commercial name for a particular gonadotrophin-releasing hormone (GnRH)-based emulsion) was tested in adult female white-tailed deer in a fenced herd near Silver Spring, Maryland, USA. Observations of udder condition were used to identify does that had become pregnant. Necropsy observations, histopathology and serum concentrations of anti-GnRH antibodies, luteinising hormone and progesterone were used to compare health and reproductive status of treated (n = 28) and control (n = 15) deer. After receiving one injection of GonaCon, 88% of treated deer did not become pregnant during the first year and 47% did not become pregnant during the second year after vaccination. No adverse health effects related to vaccination with GonaCon were detected, except for localised injection-site reactions in five (29%) of 17 examined, vaccinated deer. Treatment with GonaCon can be a safe and effective means of inducing temporary infertility in wild white-tailed deer. Ultimately, the management value of GonaCon will be determined by natural-resource professionals who use it as one of many tools to manage deer populations.

THE EFFECT OF CYPROTERONE ACETATE ON THE PLASMA GONADOTROPHIN RESPONSE TO GONADOTROPHIN RELEASING HORMONE

1976 ◽  
Vol 81 (3) ◽  
pp. 680-684 ◽  
Author(s):  
Richard A. Donald ◽  
Eric A. Espiner ◽  
R. John Cowles ◽  
Joy E. Fazackerley
Keyword(s):  
Testosterone Level ◽  
Cyproterone Acetate ◽  
Luteinising Hormone ◽  
Follicle Stimulating Hormone ◽  
Plasma Testosterone ◽  
Plasma Testosterone Level ◽  
Releasing Hormone ◽  
Lh Release ◽  
Gonadotrophin Releasing Hormone ◽  
Male Patients

ABSTRACT Cyproterone acetate (100–150 mg daily) was administered to 8 male patients with excessive libido. Within 3 months a significant fall (P < 0.02) in plasma testosterone was demonstrated. The plasma luteinising hormone (LH) and follicle stimulating hormone (FSH) responses to gonadotrophin releasing hormone (LH/FSH-RH) were also significantly impaired (P < 0.05). A direct correlation between the resting plasma testosterone level and the LH response to LH/FSH-RH was demonstrated (r = 0.743). It is concluded that the fall in plasma testosterone levels in patients receiving cyproterone acetate may be attributed to suppression of LH release, rather than an antiandrogen effect on the testis or hypothalamus.

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