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The aims of the present study were to determine the effects of insulin, in vitro , on: (1) the viability and growth of domestic cat ovarian follicles; (2) mRNA expression of genes regulating steroidogenesis (cytochrome P450 family 17 subfamily, A polypeptide 1 (Cyp17a1), cytochrome P450 family 19 subfamily, A polypeptide 1 (Cyp19a1) and steroidogenic acute regulatory protein (Star)) and water transport (aquaporins (AQPs) Aqp1 , Aqp3 , Aqp7 , Aqp9); and (3) steroid production (17β-oestradiol (E2), progesterone (P4), androstenedione (A4)). Cat secondary follicles were isolated from ovarian cortices and cultured in 0 (Control), 1 or 10 µg mL−1 insulin for 14 days (Day 0 = culture onset). Follicle and oocyte viability (based on neutral red staining), diameter and antrum formation were assessed every 72 h and at the end of incubation (Day 14). Expression of steroidogenic and water transport genes was evaluated on Days 0, 6 and 12, and E2, P4 and A4 concentrations in the culture medium were determined on Day 12. By Day 14, 1 and 10 µg mL−1 insulin had significantly promoted (P < 0.05) both antrum formation in a mean (± s.e.m.) 26.9 ± 9.0% and 78.0 ± 10.0% of follicles respectively, and follicle growth (diameter 151.4 ± 4.5 and 169.9 ± 10.5 µm respectively) compared with Control (antrum formation in 3.3 ± 3.3% of follicles and follicle diameter 129.1 ± 6.6 µm). High insulin (10 µg mL−1) treatment increased follicle viability compared with Control (86.0 ± 9.8% vs 38.1 ± 10.9% respectively; P < 0.05). However, insulin had no beneficial effect (P > 0.05) on oocyte diameter. Cyp17a1 expression on Days 6 and 12 was higher (P < 0.05) in follicles cultured in the low (1 µg mL−1) compared with high (10 µg mL−1) insulin treatment, with no significant difference between low or high insulin vs Control groups. Star expression was higher (P < 0.01) in the low insulin compared with Control group on Day 6, but Star was undetectable in the high insulin group by Day 12. Compared with high insulin, low insulin increased (P < 0. 05) Aqp1 expression on Day 6, but there were no significant differences between these two groups on Day 12. In contrast, high insulin decreased (P < 0.05) Aqp9 transcript levels compared with Control. Only P4 production was affected by insulin, with P4 concentrations in the medium being higher (P < 0. 05) in the low compared with high insulin and Control groups. In summary, the findings indicate that insulin promotes cat ovarian follicle growth and survival in vitro , including enhanced antrum formation, with the likely mechanism involving temporal expression of Cyp17a1 , Star and Aqp9 genes. Insulin is a key regulator of the growth and differentiation of secondary follicles. The aim of the present study was to determine the effects of insulin on in vitro viability and growth of domestic cat ovarian follicles. The findings indicate that insulin promotes cat ovarian follicle survival and growth and affects the temporal expression of the cytochrome P450 family 17 subfamily, A polypeptide 1 (Cyp17a1), steroidogenic acute regulatory protein (Star), and aquaporin 9 (Aqp9) genes. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the guest editors discusses about biobanking.

In the present study we examined the effects of stem cell factor (SCF; 50 vs 100 ng mL-1) alone or in combination with epidermal growth factor (EGF; 100 ng mL-1) on: (1) the in vitro viability and growth of cat follicles within ovarian cortices; (2) phosphatidylinositol 3-kinase (PI3K)/AKT and mitogen-activated protein kinase (MAPK) phosphorylation; and (3) c-kit and FSH receptor (FSHr) mRNA expression. At 100 ng mL-1, SCF increased (P⩽0.05) the percentage and size of secondary follicles after 14 days of in vitro culture and sustained AKT phosphorylation after 3 days incubation. EGF suppressed this beneficial effect and reduced (P⩽0.05) the percentage of structurally normal follicles and FSHr expression when combined with 100 ng mL-1 SCF. Expression of c-kit mRNA was higher (P⩽0.05) in the presence of 100 ng mL-1 SCF compared with fresh follicles and cohorts cultured under other conditions. A c-kit inhibitor suppressed follicle growth and reduced AKT phosphorylation. Collectively, the results demonstrate that SCF promotes cat follicle development by upregulating c-kit mRNA expression and AKT phosphorylation. EGF suppresses the stimulating effect of SCF, leading to downregulation of FSHr expression. [ABSTRACT FROM AUTHOR]

Understanding stage-specific requirements of mammalian folliculogenesis is limited in the domestic dog. The present study examined the effects of two potential regulators of dog follicle growth and survival in vitro, namely the original stage of the follicle (i.e. preantral (≤230 µm diameter) vs early antral (diameter from >230 to ≤330 µm) and FSH and/or LH concentrations. After isolation and alginate encapsulation, follicles were cultured in 0, 1, 10 or 100 µg mL-1 FSH and 0, 1 or 10 ng mL-1 LH for 20 days. Regardless of stage, FSH promoted growth, but LH did the same only in the absence of FSH. Production of 17β-oestradiol and progesterone was detectable, indicating theca cell activity. The greatest growth occurred in preantral (mean (± s.d.) 61.4 ± 25.9%) versus antral (42.6 ± 20.3%) follicles, but neither developmental stage nor gonadotropin affected survival. Antrum detection was minimal due, in part, to antral collapse, and oocytes exhibited an increasingly pale appearance and chromatin degeneration over time. The results demonstrate that pre-and early antral stage dog follicles encapsulated in alginate grow significantly in vitro. However, because FSH and LH alone or in combination fail to promote antrum development, the next step is identifying factors that enhance antral expansion. [ABSTRACT FROM AUTHOR]

Understanding stage-specific requirements of mammalian folliculogenesis is limited in the domestic dog. The present study examined the effects of two potential regulators of dog follicle growth and survival in vitro, namely the original stage of the follicle (i.e. preantral (≤230 μm diameter) vs early antral (diameter from >230 to ≤330 μm) and FSH and/or LH concentrations. After isolation and alginate encapsulation, follicles were cultured in 0, 1, 10 or 100 mgmL -1 FSH and 0,1 or 10 ng mLsup -1 LH for 20 days. Regardless of stage, FSH promoted growth, but LH did the same only in the absence of FSH. Production of 17β-oestradiol and progesterone was detectable, indicating theca cell activity. The greatest growth occurred in preantral (mean (± s.d.) 61.4 ± 25.9%) versus antral (42.6 ± 20.3%) follicles, but neither developmental stage nor gonadotropin affected survival. Antrum detection was minimal due, in part, to antral collapse, and oocytes exhibited an increasingly pale appearance and chromatin degeneration over time. The results demonstrate that pre- and early antral stage dog follicles encapsulated in alginate grow significantly in vitro. However, because FSH and LH alone or in combination fail to promote antrum development, the next step is identifying factors that enhance antral expansion. [ABSTRACT FROM AUTHOR]