فهرست مطالب m.h. nasr

The aim of the present study was to understand if EBs can promote generation of neurons following co-culture with chick embryo somites.

The mouse ES cells line Royan B1 were cultured in hanging drops to induce embryoid bodies (EBs) formation. Then RA was added to some EBs according to 2-/2+/2+ protocol to evaluate the potential of their neuron generation. Somites were isolated from the chick embryos and then embedded in alginate solution. Finally alginate beads containing somites were co-cultured with EBs as 1:1 and 4:1 ratio.

Mean percentage of EBs containing neurons in RA somite 4:1 somite 1:1 and control were 82.8% 35.3% 21.1% and 4.8% respectively. Our results showed that EBs can promote generation of neurons following co-culture with somites and somite 4:1 had more profound effect on neural induction compared to somite1:1. The neurons were formed rapidly in RA and somites groups than control group. The somite groups induced higher rosette formation which had the capacity to generate neurons upon isolation and replating. Finally the neural properties were confirmed by immunocytochemistry procedures.

Chick embryonic somites can induce ES cells –derived EBs to generate neurons in vitro and may lead to formation of rosette structures with neuron formation capacity.

Glycerol has been the most widely used cryopreservation agent for spermatozoa and a wide range of factors affects its action on sperm viability and fertilizing capacity. Moreover egg yolk is a common constituent of semen diluents protects the spermatozoa against cold shock and confers protection during freezing and thawing. The aim of this study was to investigate of different glycerol and egg yolk concentration for optimum freezing of ram semen. Nine semen extender with different concentration of egg yolk (10% 15% 20%) and glycerol (4%6%8%) in a Tris-based media were tested for cryopreservation of semen. Semen was collected from Bakhtiari rams by an artificial vagina (38-40°C) two consecutive semen collections from each ram were pooled. The ejaculates were diluted with each extender cooled to 5°C and left for 2 hours. Thereafter it was packed in 0.5 ml straws (final cellular concentration 100-200 ×106spz/ml). Then the frozen straws in nitrogen vapors (5 cm above nitrogen liquid). the straws were then stored in liquid nitrogen until further use. The results showed that frozen sperm in all treatment groups had motility after thawing but the percentage of motility in different groups are different. In conclusion the results of present study indicate that the 20% egg yolk – Tris – 8% glycerol extender was significantly superior to other extender in protecting the sperm during freezing and thawing and saving the motility of spermatozoa. While the 10% egg yolk – Tris – 4% glycerol show the lowest motility after freezing thawing.