الفهرس 
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Abstract
Folliculo-stellate cells are agranular star-like cells that form a network extending throughout the whole anterior pituitary gland. These cells are connected by gap junctions in normal mature rats.
These gap junctions allow metabolic and electrical coupling between folliculostellate cells and produce a kind of synchronized syncytium within the anterior pituitary gland.
Previous studies reported that these gap junctions could first be observed on day 20 after birth, and increase in number until reach the normal adult level by day 40 (after birth).
In the same period of time (ie : between days 20 and 40 after birth) , rats undergo a rapid sexual maturation that includes changes in the level of serum concentration of sex steroids.
The current study aims to document the effect of sex steroids on gap junctions between follicoulostellate cells.
3 groups of rats (at age of 60 days) were used in this work: - group A (control group) : injected with sesame oil.
- group B : male rats injected with testosterone.
- group C : female rats injected with progesterone.
In all groups, folliculostellate cells were distinguished by absence of granules in their cytoplasm and by being found surrounding
follicular-like cavities, with small microvilli projecting from folliculostellate cells into these cavities. Also, the presence of lysosomes in the cytoplasm of these cells was another notable criterion.
- Gap junctions were present in all of the 3 test groups, but the rate of their occurence was different through the 5 days of the study, as follows:
• In group A (the control group) : The rate of gap junctions remained constant (0.17 ± 0.04 to 0.18 ± 0.05 junction per follicle) from day 1 to 5 after injections.
• In group B : The rate of gap junctions increased to reach a peak on day 3 after testosterone injection (0.44 ± 0.07 junction per follicle) then decreased to reach the basal level on day 5 after injection.
• In group C : The rate of gap junctions increased to reach a peak on day 3 after progesterone injection (0.46 ± 0.06 junction per follicle) then decreased to reach the basal level on day 5 after injection.
from this, It can be concluded that testosterone increase the rate of gap junctions in between folliculostellate cells in male rats. while progesterone increase it in female rats.