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• Follicular development of in the whooping crane female (Grus americana) can be monitored by weekly ultrasound examination. • Follicular dynamics and hormonal patterns of the female whooping crane are similar to those of other avian species. • The failure of small, yolky follicles to enter the follicular hierarchy that are responsive to follicle stimulating hormone was the likely cause of no egg production in the whooping crane. • Small yolk laden follicles are responsive to follicle stimulating hormone. However, their failure to enter the follicular hierarchy during non-laying cycles of female whooping cranes was considered causative of a lack of egg production. For endangered species managed ex situ , production of offspring is a key factor to ensure healthy and self-sustaining populations. However, current breeding goals for the whooping crane (Grus americana) are impeded by poor reproduction. Our study sought to better understand mechanisms regulating ovarian function in ex situ managed whooping cranes and the regulatory function of the hypothalamic-pituitary–gonadal (HPG) axis in relation to follicle formation and egg laying. To characterize hormonal regulation of follicular development and ovulation, we collected weekly blood samples from six female whooping cranes during two breeding seasons, for a total of 11 reproductive cycles. The plasma samples were assessed for follicle stimulating hormone, luteinizing hormone, estradiol, and progesterone and the yolk precursors vitellogenin and very low-density lipoprotein. Ultrasonographic examination of the ovary was conducted at the time of blood collection. Preovulatory follicles (>12 mm) were present in laying cycles (n = 6) but absent in non-laying cycles (n = 5). The patterns of plasma hormone and yolk precursor concentrations corresponded to the stage of follicle development. Specifically, gonadotropin and yolk precursor concentrations increased as follicles transitioned from the non-yolky to yolky stage but did not increase further as the follicle advanced to preovulatory and ovulatory stages. Estrogen and progesterone concentrations increased as follicle size increased and reached peak concentrations (P < 0.05) when follicles developed to ovulatory and preovulatory stages, respectively. While overall mean circulating gonadotropin, progesterone, and yolk precursor concentrations did not differ for laying versus non-laying cycles, mean plasma estradiol in laying cycles was significantly higher than that in non-laying cycles. In summary, the findings suggested that disruption of mechanisms regulating follicle recruitment is likely responsible for the oviposition failure of the captive female whooping crane. [ABSTRACT FROM AUTHOR]

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]