Effects of the preservation medium and storage duration of domestic cat ovaries on the maturational and developmental competence of oocytes in vitro

Effects of storing queen ovaries in saline solution at 22 C on ovarian follicle integrity and oocyte quality and maturation

This study evaluated the effects of storing queen ovaries in saline at 22 °C for up to 12 h. Two experiments were conducted. In the first experiment, ovaries from five queens were sectioned into four fragments; stored for 4, 8, or 12 h; and histologically analyzed to assess follicular morphology (Grades I-IV). In the second experiment, ovaries from 15 additional queens were stored under the same conditions, after which cumulus-oocyte complexes (COCs) were retrieved and graded (I-IV); only Grades I and II underwent in vitro maturation to assess cumulus expansion and meiotic status. The effects of storage on follicle morphology, COC quality, and maturation were analyzed using the chi-square test, while Spearman's correlation assessed the relationship between storage time and follicle morphology. The results showed that early-stage follicles were more sensitive to short-term storage, with 56 %, 22 %, 2 %, and 0 % of primordial, primary, secondary, and antral follicles, respectively, classified as Grade IV after 4 h. Grade I follicles declined to 0 % across all developmental stages after 12 h. Significant correlations were found between storage duration and follicle morphology (Grade I: r = -0.92, Grade II: r = -0.65, Grade III: r = 0.68; P < 0.05), while Grade IV remained unchanged. COC recovery did not differ across storage times (P > 0.05), with >60 % classified as Grade III or IV at all time points. After 12 h, there was a significant reduction in Grade I COCs, cumulus expansion, and the percentage of oocytes reaching metaphase II (P < 0.05). In conclusion, while storing queen ovaries in saline at 22 °C negatively affects follicular morphology - particularly preantral follicles - oocytes can still be recovered up to 8 h post-storage, without compromising COC quality or maturation potential.

Establishment of feline embryonic stem cells from the inner cell mass of blastocysts produced in vitro

Introduction

The rising number of cats as pets and the growing interest in animal welfare have led to an increased need for the latest treatments in feline veterinary medicine. Among these, veterinary regenerative medicine using pluripotent stem cells is gaining significant attention. However, there have been no reports on establishing feline embryonic stem cell (ESC) lines that possess the pluripotent potential and the ability to differentiate into three germ layers.

Methods

In this study, we isolated three inner cell masses from feline in vitro-derived blastocysts and subcultured them in a chemically defined medium (StemFit AK02N). We assessed the expression of undifferentiated markers, the ability to differentiate into the three germ layers, and the karyotype structure.

Results

We established three feline ESC lines. Feline ESCs exhibited positive staining for alkaline phosphatase. RT-qPCR analysis revealed that these cells express undifferentiated marker genes in vitro. Immunostaining and flow cytometry analysis demonstrated that feline ESCs express undifferentiated marker proteins in vitro. In the KSR/FBS medium with or without Activin A, feline ESCs differentiated into all three germ layers (ectoderm, endoderm, and mesoderm), expressing specific marker genes and proteins for each germ layer, as evidenced by RT-qPCR, immunostaining, and flow cytometry. Furthermore, we confirmed that feline ESCs formed teratomas comprising all three germ layers in mouse testes, demonstrating de novo pluripotency in vivo. We also verified that the feline ESCs maintained a normal karyotype.

Conclusions

We successfully established three feline ESC lines, each possessing pluripotent potential and capable of differentiating into all three germ layers, derived from the inner cell masses of blastocysts produced in vitro.

Prolonged cold-preservation of domestic cat ovarian tissue is improved by extracellular solution but impaired by the fragmentation of ovary

For domestic cats ovaries, recommended cold-storage limit is 24 h in Phosphate Buffered Saline (PBS) or Dulbecco`s PBS (DPBS). Here, we attempted to verify wheatear cat ovaries may benefit from more complex solutions during prolonged cold-storage (>24 h). First, the preservation capabilities of extracellular (SP+), intracellular (UW) solutions and DPBS supplemented with glutathione (DPBS+GSH) were compared using ovary fragments from the same ovary (n=10). Intact ovary stored in DPBS served as a control. Ovaries were kept at 4 °C for 48 h, and 72 h. In the second experiment, first ovary was stored in DPBS, second in SP+ or UW solution for 48 h (n = 12). Ovaries pairs stored in DPBS for 24 h served as a control (n=8). Tissue samples were evaluated directly after cold-storage and after following 24 h in vitro culture. Ovarian follicle morphology, apoptosis rates (cleaved caspase-3, TUNEL), and follicular growth activation (Ki-67) were assessed. Ovary fragmentation impaired follicular morphology preservation upon cold-storage comparing to intact ovary. However, ovarian fragments stored in UW for 48 h and in SP+ for 72 h presented better morphology than DPBS+GSH group. Comparison of intact ovaries cold-storage for 48 h showed that SP+ provided superior follicular morphology over DPBS, and it was comparable to the outcome of 24-hour storage. No follicular activation after in vitro culture was observed. Nevertheless, tissue culture increased considerably caspase-3 cleavage and TUNEL detection. The ovary fragmentation prior to cold-storage is not recommended in domestic cats. Replacement of DPBS with SP+ solution for whole ovary and UW solution for ovarian tissue fragments improves follicular structure preservation during 48-hour cold-storage.

Effects of glucose and trehalose on tris-citric acid-egg yolk-fructose diluents for semen cryopreservation in goat

Objectives

This study aimed to examine the impacts of the wide range of concentrations of glucose and trehalose on the tris-citric acid-egg yolk-fructose (TCEF) extenders for cryopreservation of goat semen.

Materials and Methods

The sperm sample was pooled, washed, and diluted in control (TCEF without glucose and trehalose), TCEF + glucose (75, 150, 450, and 900 mm), and TCEF + trehalose (75, 150, 450, and 900 mm). After equilibrations, the semen straws were frozen under LN2 in the LN2 tank. After LN2 storage, the straws were thawed at 37°C for 30 seconds. The sperm parameters of all study groups were checked after equilibration and freezing.

Results

After equilibration, the progressive motility (PM), total motility (TM), and viability of sperm in G-75, G-150, G-450, T-75, T-150, and T-450 were not significantly different (p < 0.05) from those in control. After cryopreservation and thawing, the PM, TM, and plasma membrane integrity (PMI) of T-150 were significantly higher (p < 0.05) than in control, G-75, G-900, T-75, and T-900. The viability of sperm in T-150 was substantially higher (p < 0.05) than in the control, whereas there was no significant difference among the control, G-75, G-900, T-75, and T-900. However, the acrosome integrity (AI) of sperm in G-900 was significantly decreased (p < 0.05) compared to the control, G-75, G-150, G-450, T-75, T-150, and T-450.

Conclusion

According to the findings, the supplementation of 150 mm trehalose in the TCEF diluent was more efficient for sperm cryopreservation in the buck as reflected by PM, TM, viability, PMI, and AI.

Effects of tris (hydroxymethyl) aminomethane and egg yolk on the cryopreservation of buck semen

Objectives

This study was designed to examine the effects of various concentrations of tris (hydroxymethyl) aminomethane (tris) and egg yolk on the quality of cryopreserved buck sperm.

Materials and Methods

The collected semen samples were pooled, washed, and diluted into five different freezing extender groups, viz., extender I (tris 0% + egg yolk 0%), extender II (tris 1.41% + egg yolk 4%), extender III (tris 2.41% + egg yolk 8%), extender IV (tris 3.41% + egg yolk 16%), and extender V (tris 4.41% + egg yolk 24%). The sperm parameter of the five groups of extenders was evaluated after equilibration and cryopreservation.

Results

The results showed that extenders II-V provided significantly higher semen progressive motility and total motility percentages than extender I after equilibration (p < 0.05). The higher percentages of semen progressive motility, total motility, viability, and plasma membrane integrity (by both HOST under light microscopy and stain after HOST under light microscopy) were found in the sperm cryopreserved with extender IV than extender I, extender II, and extender III groups after thawing (p < 0.05). In addition, semen progressive motility, total motility, and viability were not further increased, or plasma membrane integrity (by both HOST tests) was decreased by the addition of tris and egg yolk (extender V) after cryopreservation (p < 0.05).

Conclusion

In conclusion, our result indicates that the following washing, the supplementation of tris (3.41% + egg yolk 16%) on the freezing extender are suitable for improving the semen quality of buck after freezing and thawing.