No abstract

The domestic ferret is a seasonally polyoestrous species. Females reach puberty at the age of 8-12 months. Females exhibit a constant oestrus between late March and early August if they are not bred. Increasing tumescence in the pink-coloured vulva is a sign of pro-oestrus. Oestrus can persist for up to 5 months, but once ovulation is induced, either pregnancy or pseudopregnancy ensues. Follicular development and atresia overlap in such a manner that there is a recent cohort of follicles available for ovulation whenever copulation might occur. Copulation may last from 15 min to 3 h, the average being 1 h. Ovulation is induced by pressure on the cervix associated with copulation. After sufficient LH release, the pre-ovulatory follicles mature and an average of 12 oocytes (5-13) per female are ovulated 30-40 h after copulation into the ovarian bursa. The ferret oocytes are most capable of being fertilized up to 12 h after ovulation, i.e. 42-52 h after copulation. Ferret oocytes ovulate at the metaphase of the second meiotic division (MII) embedded in three layers of corona radiata cells. Embryos enter the uterus over a period of several days starting on day 5 after mating. Between days 12 and 13 after mating, the embryos have become implanted in the endometrium. Implantation in the ferret is central with rapid invasion of the uterine epithelium by the trophoblast over a broad area that eventually becomes a zonary band of endotheliochorial placenta. Gestation length is 41 days (39-42 days). The domestic ferret gives birth to an average of eight kits (1-18 kits), which weigh 6-12 g at birth.

The European mink is an endangered Mustelidae species and thus requires effective conservation measures, although little is known about reproduction in this species. In particular, preimplantation development has not been studied and, therefore, embryonic development and the growth of embryos was documented in the present study for European mink using light and fluorescent microscopy. Embryos develop in the oviducts and then migrate into the uterus on Day 6 post coitum (p.c.) at the morula stage. Embryos expanded as blastocysts from Day 7 until implantation on Day 12 p.c. Based on these findings, the use of embryo transfer for a conservation programme for the European mink was evaluated. Embryos were flushed from European mink resource females and transferred into the uterine horns of recipient hybrid females (honoriks and nohoriks). These hybrids were obtained by mating European polecat males with European mink females and vice versa. A total of 40 embryos was transferred and 20 live kits were born. The rates of pre- and postnatal survival were 50% and 70%, respectively. Both male and female offspring were lighter at birth in the embryo transfer group compared with naturally born controls, but there was no difference at 3 months of age.

No abstract

We have investigated whether 5% oxygen tension (O(2)) is beneficial for neocartilage formation when chondrocytes are cultured in transwell-COL inserts. Six million bovine primary chondrocytes were cultured in an insert with DMEM supplemented with 10% fetal bovine serum and antibiotics, with or without glucosamine sulphate (GS) in a 5% or 20% O(2) environment for 2, 4, or 6 weeks. The samples were collected for the histological staining of proteoglycans (PGs) and type II collagen, quantitative reverse transcription with the polymerase chain reaction (RT-PCR) analyses of the mRNA expression of aggrecan and procollagen α(1)(II), procollagen α(2)(I) and hyaluronan synthase 2, quantitation of PGs, and agarose gel electrophoresis. Neocartilage produced at 20% O(2) appeared larger than that at 5% O(2). Histological staining showed that more PGs and type II collagen and better native cartilage structure were produced at 20% than at 5% O(2). The thickness of neocartilage increased during the culture period. Quantitative RT-PCR showed that the procollagen α(1)(II) mRNA expression level was significantly higher at 20% than at 5% O(2). However, no significant difference in gene expression and PG content was found between control and GS-treated cultures at either 20% or 5% O(2). Thus, in contrast to monolayer cultures, engineered cartilage from scaffold-free cultured chondrocytes at 20% O(2) produced better extracellular matrix (ECM) than that at 5% O(2). PGs were mainly large. Exogenous GS was not beneficial for the ECM in scaffold-free chondrocyte cultures.