Influence of follicle size on quality of cumulus oocyte-complexes and concentration of steroids of follicular fluid in buffalo

Abstract EN

The aim of the present study was to investigate the effect of follicle size on the buffalo cumulus oocyte complexes (COCs) morphology, chromatin configuration, level of apoptosis in cumulus cells, and concentration of progesterone and estradiol-17 in buffalo follicular fluid of different follicle size.

Visible follicles were carefully isolated and classified according to their size into 3 categories <3 mm (2-3 mm), 3-5 mm and > 5 mm (5-8 mm).

A total of 295 COCs were recovered from the previous three follicle categories; COCs were classified according to number and compactness of cumulus layers.

Good quality compact COCs which used for IVM, which mostly obtained from follicles <3 and 3-5 (56-7%, 57.1) in comparison to 34.3% from large follicle.

The chromatin configuration at the time of recovery in oocytes derived from <3 mm and 3-5 mm follicles arrested at the germinal vesicle stage, 60% and 70.8% respectively.

On the other hand, highest proportion of oocyte in resumption of meiosis were found in oocyte obtained from large follicle (77.8%) Vs 40% and 29.2% from <3mm and > 3-5 mm follicle respectively.

There was a connection of cumulus morphology, chromatin configuration at the time of recovery and the follicle size.On the other hand no significant differences in maturation capacity (metaphase2)of COCs derived from different follicles diameter.

Apoptosis of cumulus at time of recovery decreased with incre-asing the follicle size, but this difference was not significant (0.9, 0.6,0.2).

After 24 hr.

IVM, an increase in apoptosis was observed in cumulus cells from all follicle size with significant (P < 0.05) increase in cumuli derived from 3-5 mm follicles compared to < 3 and >5 mm follicles (24.4 Vs 4.7,3.5) Concentration of progesterone (ng/ml)in buffalo follicular fluid was not influenced by follicle size, while concentration of estradiol-17 (ng/ml) was significant higher in follicle 3-5, >5 mm (782 ± 67 and 788 ± 67 respectively) in comparison to follicular fluid from <3 mm follicles (682 ± 67).