Theriogenology wild最新文献

{"title":"Estrous synchronization in agoutis (Dasyprocta leporina) using the Ovsynch protocol, followed by natural mating and evaluation of success via offspring birth","authors":"Kavita Ranjeeta Lall ,&nbsp;Gary Wayne Garcia","doi":"10.1016/j.therwi.2026.100161","DOIUrl":"10.1016/j.therwi.2026.100161","url":null,"abstract":"<div><div>Research on estrous synchronization and/or induction in the <em>Dasyprocta</em> species remains limited and no previous studies have confirmed reproductive success through offspring birth following hormonal synchronization protocols. This study aimed to evaluate the use of the Ovsynch protocol for estrous synchronization in <em>Dasyprocta leporina</em>, followed by natural mating and assessment of reproductive success via parturition. Five female agoutis were synchronized by firstly administering subcutaneous injections of 40 µg gonadorelin acetate (Fertiline®), followed seven days later by intramuscular injections of 2.5 mg dinoprost tromethamine (Lutalyse®) and a second set of subcutaneous injections of 40 µg gonadorelin acetate (Fertiline®) two days after. A proven male was introduced at a time corresponding to the expected onset of estrus based on previously established data. Animals were monitored daily and reproductive success was determined by offspring birth. Three of the five females (60%) produced offspring, including two single births and one twin birth. Birth weights ranged from 222 to 250 g and estimated gestational lengths (107–120 days) were consistent with published values for the species. These findings provide preliminary evidence that the Ovsynch protocol may support successful reproduction in <em>D. leporina</em> under low-intervention conditions. However, due to the small sample size, absence of a control group and lack of direct monitoring, the results should be interpreted cautiously. This study contributes baseline data for the development of assisted reproductive techniques in this species.</div></div>","PeriodicalId":75220,"journal":{"name":"Theriogenology wild","volume":"8 ","pages":"Article 100161"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147991515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The influence of ejaculate traits on strategies for genome resource banking in tigers (Panthera tigris ssp.)","authors":"Shelley E.S. Sandmaier,&nbsp;Christina Ploog,&nbsp;Jason R. Herrick","doi":"10.1016/j.therwi.2026.100163","DOIUrl":"10.1016/j.therwi.2026.100163","url":null,"abstract":"<div><div>The Tiger Species Survival Plan has established a genome resource bank to store cryopreserved spermatozoa from all adult males from all three of the populations managed in U.S. zoos (Amur, <em>Panthera tigris altaica</em>, Sumatran, <em>P.t. sumatrae</em>, and Malayan, <em>P.t. jacksoni</em>). We analyzed 104 ejaculates collected from 69 individuals (Amur n = 32, Sumatran n = 23, Malayan n = 14, ages 2 – 18 y, collected between 2013 and 2023). The results provided the opportunity to characterize reproductive traits of males in the current population and determine how the number of spermatozoa produced in a single collection will affect future strategies to maintain the GRB given current success rates for artificial insemination, in vitro fertilization, and embryo transfer. Semen was collected via electroejaculation, subjected to analysis, and cryopreserved. Total sperm count per ejaculate did not differ by subspecies (population average = 175.2 ± 22.5 ×10⁶). Although most spermatozoa were motile (population average = 67.1 ± 2.2%), the number of morphologically normal was very low (average = 14.5 ± 1.0%). This percentage of normal sperm is much lower than that of previous studies of the North American population. For the genetics of each individual to be fully represented in a GRB, there must be sufficient spermatozoa to produce 10 offspring through assisted reproduction, which we estimate to be 30 procedures requiring 150 million motile spermatozoa if laparoscopic oviductal AI is used. Population managers must plan for frequent collections throughout the reproductive lifespan of the male. In addition, further studies of in vitro ART are warranted to maximize the potential of collected samples.</div></div>","PeriodicalId":75220,"journal":{"name":"Theriogenology wild","volume":"9 ","pages":"Article 100163"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148193470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seasonal switches in testicular gene programs underlie spermatogenic plasticity in the large Japanese field mouse (Apodemus speciosus)","authors":"Kento Annaka ,&nbsp;Syun Tokita ,&nbsp;Jin Shibata ,&nbsp;Reiri Fukuda ,&nbsp;Hikari Ikema ,&nbsp;Akifumi Nakata ,&nbsp;Tomisato Miura ,&nbsp;Hideaki Yamashiro","doi":"10.1016/j.therwi.2026.100147","DOIUrl":"10.1016/j.therwi.2026.100147","url":null,"abstract":"<div><div>Seasonally bred mammals undergo cyclical changes in spermatogenesis to align their reproductive functions with the environmental conditions. The large Japanese field mouse (<em>Apodemus speciosus</em>), a rodent endemic to Japan, exhibits pronounced seasonal plasticity in its testicular activity, alternating between active spermatogenesis and testicular regression during the breeding and non-breeding seasons, respectively. However, the molecular mechanisms underlying this seasonal regulation are poorly understood. In this study, we conducted RNA sequencing of testicular tissues collected from wild <em>A. speciosus</em> during breeding and non-breeding seasons. Differential gene expression analysis identified 2000 transcripts showing significant seasonal variations. Genes upregulated during the non-breeding season were associated with immune regulation, the oxidative stress response, and transcriptional repression. Gene Ontology enrichment analyses confirmed season-specific transitions in biological processes, such as gamete generation, hormone signaling, and immune homeostasis. These results suggest that <em>A. speciosus</em> employs a reversible and highly coordinated transcriptional program to toggle between the reproductively active and quiescent testicular states. This study represents the first testis-specific transcriptomic study of <em>A. speciosus</em> and provides novel insights into the molecular regulation of seasonal spermatogenesis in wild mammals. Our findings establish a valuable framework for future research on reproductive seasonality and contribute to a broader understanding of fertility adaptations under natural ecological conditions.</div></div>","PeriodicalId":75220,"journal":{"name":"Theriogenology wild","volume":"8 ","pages":"Article 100147"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147396651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessment of ultra-rapid freezing as a simplified, field-friendly technique for semen cryopreservation in wild ocelots (Leopardus pardalis) and bobcats (Lynx rufus) in southern Texas","authors":"Ashley M. Reeves ,&nbsp;William F. Swanson ,&nbsp;Tyler A. Campbell ,&nbsp;Michael E. Tewes ,&nbsp;Amy Miller ,&nbsp;Cary Springer ,&nbsp;Debra L. Miller","doi":"10.1016/j.therwi.2026.100146","DOIUrl":"10.1016/j.therwi.2026.100146","url":null,"abstract":"<div><div>Ocelot (<em>Leopardus pardalis</em>) populations in southern Texas have shown declines in genetic variability over time. Assisted reproductive technologies (ARTs<span><span>¹</span></span>), such as semen cryopreservation and artificial insemination (AI<span><span>²</span></span>), can help improve species sustainability by preserving genetic diversity and connecting populations by transport of frozen gametes. Traditionally, felid semen has been cryopreserved by slow freezing in plastic straws (STRAW) for liquid nitrogen storage. However, another technique, ultra-rapid freezing (URF<span><span>³</span></span>), would decrease the time and effort needed to preserve samples and potentially facilitate cryopreservation in the field. The goal of this study was to compare the effectiveness of URF to traditional STRAW freezing with two wild felid species living in southern Texas. Semen was collected by urethral catheterization (UC<span><span>⁴</span></span>) and electroejaculation (EEJ<span><span>⁵</span></span>) and frozen using both cryopreservation methods from 12 free-ranging adult felids (n = 6 ocelots; n = 6 bobcats (<em>Lynx rufus</em>)). Post-thaw, sperm samples were assessed for progressive motility, acrosomal integrity, and heterologous in-vitro fertilization (IVF<span><span>⁶</span></span>) of domestic cat oocytes. For both species, sperm acrosomal integrity, percent progressive motility, and rate of forward progression declined (p &lt; 0.001) over time, with no difference (p &gt; 0.05) between cryopreservation methods. Frozen-thawed spermatozoa from both species fertilized mature domestic cat oocytes (range, 8.3 – 100 %), and oocyte cleavage percentage did not differ (p &gt; 0.05) between cryopreservation techniques. Our initial results suggest that URF, in combination with UC, may allow wildlife veterinarians to routinely collect and bank semen samples from free-ranging cats for conservation purposes.</div></div>","PeriodicalId":75220,"journal":{"name":"Theriogenology wild","volume":"8 ","pages":"Article 100146"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145977593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ovulation synchronization and fixed-time artificial insemination in bison using washed frozen sperm","authors":"S.E. Pezo ,&nbsp;D.R. Farmer ,&nbsp;S.X. Yang ,&nbsp;M. Anzar ,&nbsp;K. Rajapaksha ,&nbsp;G. Mastromonaco ,&nbsp;D. Wickramasingha ,&nbsp;J. Singh ,&nbsp;G.P. Adams","doi":"10.1016/j.therwi.2026.100150","DOIUrl":"10.1016/j.therwi.2026.100150","url":null,"abstract":"<div><div>The objective of the study was to improve assisted reproductive technologies needed to establish and deploy a bison genome biobank. In Experiment 1, ovulation was synchronized with either estradiol + progesterone (n = 16) or a high-dose of GnRH (n = 17), and bison were inseminated with sperm washed using a density gradient centrifugation (DGC) procedure with trypsin before cryopreservation. No difference was found in ovulation rate (combined, 85%) or interval from ovulation-inducing treatment to ovulation (1.3 ± 0.1 days) between groups, but pregnancy rates were unexpectedly low (3/28). In Experiment 2, the fertilizing capacity of DGC trypsin-washed versus unwashed sperm was tested by FTAI after synchronizing female bison using the GnRH protocol. Again, pregnancy rates were low (0/14 using DGC trypsin-washed sperm and 4/17 using unwashed sperm). In Experiment 3, the efficacy of two ovarian synchronization protocols was compared (high-dose GnRH vs hCG). Ovulation rates and synchrony were satisfactory and not different between groups (combined, 75% in 1.5 ± 0.1 days). The DGC washing procedure without trypsin increased the proportion of sperm with normal morphology and decreased the proportion with DNA fragmentation (P &lt; 0.01; Experiment 4). The steroid-based versus high-dose GnRH-based ovarian synchronization protocols were equally efficacious (Experiment 5), but the pregnancy rate tended to be higher after FTAI with DGC washed sperm without trypsin vs unwashed sperm (8/12 vs 2/9; P = 0.08). Among experiments, pregnancy rates were highest (P &lt; 0.01) in bison inseminated with sperm washed using DGC without trypsin. The use of trypsin in the DGC washing procedure had a deleterious effect on the in vivo fertilization capability of bison semen.</div></div>","PeriodicalId":75220,"journal":{"name":"Theriogenology wild","volume":"8 ","pages":"Article 100150"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147396650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigating the use of trehalose, egg-yolk, and dimethyl sulfoxide, in white spotted bamboo shark (Chiloscyllium plagiosum) sperm cryopreservation media","authors":"James D. Gillis ,&nbsp;Gisele A. Montano ,&nbsp;Linda M. Penfold ,&nbsp;Todd R. Robeck","doi":"10.1016/j.therwi.2025.100143","DOIUrl":"10.1016/j.therwi.2025.100143","url":null,"abstract":"<div><div>It is estimated that over one-third of elasmobranch species are threatened with extinction. Sperm cryopreservation can theoretically augment population management through the development of gamete biobanks combined with artificial insemination to maintain genetic diversity. However, attempts at cryopreserving white spotted bamboo shark’s sperm, a potential elasmobranch model, have resulted in a poor post-thaw motility (<span><math><mo>≤</mo></math></span> 5 %), thus hindering the development of biobanks. Therefore, the objective of this study was to investigate the effect of cryoprotecting agents’ trehalose (Tre), egg-yolk (EY), and dimethyl sulfoxide (DMSO) on white spotted bamboo shark sperm motility and plasma membrane integrity post-thaw as first steps to developing a cryopreservation protocol. Motility was assessed using both subjective assessment and computer assisted sperm analysis (CASA) and was found to be correlated (P &lt; 0.0000002; R = 0.908). Highest post-thaw motilities at 0 h were achieved using a combination of E-HBSS media containing 5 % Tre, 20 % EY, and 10 % DMSO (subjective total motility 21.3 <span><math><mo>±</mo></math></span> 1.1 %, CASA total motility 21.3 <span><math><mo>±</mo></math></span> 1.2 %, and PMI 26.6 <span><math><mo>±</mo></math></span> 1.6 %). However, it was noted that ∼40–50 % motility and PMI, respectively, were lost upon addition of DMSO prior to cryopreservation. The improved motility and PMI reported in the present study provide a foundation to further enhance elasmobranch sperm cryopreservation protocols.</div></div>","PeriodicalId":75220,"journal":{"name":"Theriogenology wild","volume":"8 ","pages":"Article 100143"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145791685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reproductive conditioning of captive lionesses: Assessments of vaginal microbiota, oxidative stress and hormonal profile","authors":"Vincenzo Cicirelli ,&nbsp;Matteo Burgio ,&nbsp;Daniela Olivero ,&nbsp;Pietro Laricchiuta ,&nbsp;Giovanni Michele Lacalandra ,&nbsp;Alice Carbonari ,&nbsp;Stefano Carbonara ,&nbsp;Annalisa Rizzo","doi":"10.1016/j.therwi.2026.100157","DOIUrl":"10.1016/j.therwi.2026.100157","url":null,"abstract":"<div><div>Reproductive management in captive large felids represents a major challenge for zoological institutions and conservation programs. This descriptive and exploratory study investigated endocrine profile, oxidative status, and vaginal microbiota in seven captive African lionesses (<em>Panthera leo</em>) with different reproductive conditions: two intact cycling females, three females treated with a deslorelin (GnRH agonist) implant, and two ovariectomized females. During routine health checks under general anesthesia, blood samples and vaginal swabs were collected to assess serum anti-Müllerian hormone (AMH), estradiol, progesterone, oxidative stress markers (d-ROMs and BAP), and vaginal microbiota composition through 16S rRNA gene sequencing. AMH concentrations clearly differentiated intact lionesses from ovariectomized individuals, while implanted females showed intermediate AMH values. Estradiol and progesterone profiles supported effective pharmacological ovarian suppression in implanted lionesses. Oxidative markers showed inter-individual variability. Lionesses with endocrine profiles comparable with active ovarian function displayed higher d-ROMs values. Vaginal microbiota composition at the phylum level was heterogeneous across individuals, without consistent patterns uniquely associated with a specific reproductive condition. Overall, this study provides preliminary integrated data on endocrine, oxidative, and microbial parameters in captive lionesses. AMH may represent a useful tool for assessing ovarian status, while the observed variability in oxidative and microbial profiles warrants further investigation through larger, longitudinal, and functionally integrative studies.</div></div>","PeriodicalId":75220,"journal":{"name":"Theriogenology wild","volume":"8 ","pages":"Article 100157"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147797838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effect of season and devil facial tumour disease on the quantitative histology of the tasmanian devil (Sarcophilus harrisii) testis and ovary","authors":"Ahna Ripper-Wilson,&nbsp;Tamara Keeley,&nbsp;Chiara Palmieri,&nbsp;Stephen Johnston","doi":"10.1016/j.therwi.2026.100168","DOIUrl":"10.1016/j.therwi.2026.100168","url":null,"abstract":"<div><div>Devil facial tumour disease (DFTD) has contributed significantly to the rapid decline of wild Tasmanian devil populations. While the seasonality and oestrous cycle of the female Tasmanian devil have been characterised through endocrine profiles and behavioural studies, the reproductive seasonality of the male Tasmanian devil has only been briefly investigated. In this study, archival fixed and embedded testicular and ovarian tissues collected from Tasmanian devils euthanised due to DFTD were retrospectively analysed to examine the potential effects of season and DFTD on the quantitative histology of the Tasmanian devil gonads. Findings provide baseline histological information, exploratory evidence of seasonal patterns, and a limited investigation of variation across DFTD stages. In the testes, interstitial endocrine (Leydig) cell relative proportions were highest during autumn. Spermatids were present throughout the year, and relative testicular cell proportions were similar between animals with and without DFTD. Relative proportions of Tasmanian devil ovarian tissue containing a high proportion of follicles, with no antral follicles, were highest in spring and lowest in autumn, whilst small antral follicles were highest in autumn and lowest in spring. Corpora lutea were most abundant throughout autumn and winter, whilst corpora albicantia peaked in spring and summer. The study could not robustly evaluate DFTD effects on ovarian histology due to the absence or near absence of disease-free and metastatic tissue samples. Overall, the presence of post-meiotic germ cells across seasons suggests that spermatogenic activity may occur year-round in males, while no significant association between DFTD status and the measured testicular tissue proportions was detected in the available samples. The ovarian histological patterns observed align with previous studies on the timing of female reproductive activity.</div></div>","PeriodicalId":75220,"journal":{"name":"Theriogenology wild","volume":"9 ","pages":"Article 100168"},"PeriodicalIF":1.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148569141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Preliminary investigation: Down-regulation of testosterone by an anti-GnRH immunotherapeutic (Improvest®) in a Southern White Rhinoceros (Ceratotherium simum simum) Bull","authors":"Elizabeth E. Hammond ,&nbsp;Linda M. Penfold ,&nbsp;Lara C. Metrione","doi":"10.1016/j.therwi.2026.100156","DOIUrl":"10.1016/j.therwi.2026.100156","url":null,"abstract":"<div><div>The ability to maintain bull white rhinoceros (<em>Ceratotherium simum simum</em>) in breeding groups while preventing unwanted reproduction could be beneficial for bull wellbeing compared to solitary housing. To date, no contraception has been investigated for male rhinoceros species, but anti-GnRH immunotherapeutics have been used in female white and greater one-horned rhinoceros, as well as other wildlife species, to reduce reproductive steroid hormone concentrations. This study investigated the efficacy of Improvest® in down-regulating testosterone concentrations in a genetically well-represented bull white rhinoceros. Improvest® (0.6 mg; Distributed by Zoetis, Inc., Kalamazoo, MI 49007) was administered in the left triceps muscle, followed by boosters at 4, 12, 26, 42, 51, and 67 weeks. Serum testosterone was measured by enzyme immunoassay in blood samples collected voluntarily approximately weekly before and during the initial treatment, then monthly for long-term monitoring. No adverse effects from Improvest® were observed with the exception of mild swelling at the injection site. A five-fold decrease in testosterone concentrations was measured within the fourth week after the second dose, 8 weeks following initial treatment, and basal concentrations (17.3 ± 1.1 ng/mL) were maintained until a break-through increase in concentrations occurred 16 weeks after a booster injection. This case study demonstrates that testosterone concentrations can be suppressed in white rhinoceros bulls treated with Improvest®. These findings suggest anti-GnRH immunotherapeutics could be promising tools for bull rhinoceros management, and further studies of consistency in responsiveness, effects on behavior and fertility, and reversibility are merited.</div></div>","PeriodicalId":75220,"journal":{"name":"Theriogenology wild","volume":"8 ","pages":"Article 100156"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147797837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sertoli nuclear morphology in developing Sertoli/germ cell units of pelagic sharks and its association with testis remodeling in the blue shark (Prionace glauca)","authors":"Leon Mendel McClusky","doi":"10.1016/j.therwi.2026.100179","DOIUrl":"10.1016/j.therwi.2026.100179","url":null,"abstract":"<div><div>Previous histological studies of the cartilaginous fish testis that consists of spermatocysts (spherical germ/ Sertoli cell units) indicate interspecies differences in Sertoli nuclear morphology, particularly during spermatogonial cyst development. Re-examination of an archival slide collection of the degenerated testes of summer-breeding blue shark (<em>Prionace glauca</em>) revealed two categories of spermatogonial cysts, best discerned at the two-layered stage (showing perilumenar Sertoli nuclei), i.e. cysts with large oblong, smooth contoured Sertoli nuclei (or <em>Osc</em> cysts) and cysts with sharp-edged pyramidal to polygonal Sertoli nuclei (or <em>Spp</em> cysts). This study investigated the association between the latter two cyst types and two histological perturbations at the mitosis – meiosis transition, i.e. multinucleate spermatogonial deaths (MNC) and an early recovery phase condition featuring phagocytically cleared areas. Microscopic analyses of 4 lines radiating out from the immature pole revealed that the MNC group’s median percentage <em>Spp</em> cysts was significantly (<em>P &lt; 0.01</em>) 4-fold greater than that of the <em>Osc</em> cysts, with the converse calculated for the early recovery phase group’s two-layered cysts. Similarly, in the early recovery phase group, the median percentage <em>Osc</em> cysts with ≥ 1 Sertoli mitotic figure was significantly (<em>P &lt; 0.05</em>) almost 30-fold greater than that of the <em>Spp</em> cysts. For purposes of comparison with another co-landed pelagic species, cyst assembly and small cysts in the testes of sexually mature shortfin mako sharks (n = 4) were analyzed. Sertoli cells derived from homogeneous round somatic precursor cells. Thus, the trait of contrasting Sertoli nuclear morphologies in <em>Prionace</em> is not shared by all pelagic species.</div></div>","PeriodicalId":75220,"journal":{"name":"Theriogenology wild","volume":"9 ","pages":"Article 100179"},"PeriodicalIF":1.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149050718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}