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Follicular development in the sheep after priming with PMSG.
Journal of Reproduction and Fertility
|March 1, 1983
Summary
Administering pregnant mare serum gonadotropin (PMSG) early in the sheep estrous cycle causes follicular cysts. These cysts luteinize and secrete progesterone, with thecal cells potentially mimicking granulosa cell functions.
Area of Science:
- Reproductive biology
- Endocrinology
- Veterinary science
Background:
- Follicular cysts can form in sheep following pregnant mare serum gonadotropin (PMSG) administration.
- The timing of PMSG administration influences cyst development and ovulation rates.
Purpose of the Study:
- To investigate the morphological and endocrine consequences of early-cycle PMSG administration in sheep.
- To characterize the cellular changes within follicular cysts induced by PMSG.
Main Methods:
- Sheep were administered PMSG on Days 2 or 3 of their estrous cycle.
- Follicular morphology and cellular structures were examined at Days 8 or 9 post-injection.
- Hormone secretion from luteinized follicles was analyzed.
Main Results:
- Early PMSG administration (Days 2-3) led to follicular cysts with lost membrana granulosa.
- The theca interna of these cysts luteinized, secreting progesterone.
- The steroid-secreting cells resembled large luteal cells of granulosa cell origin.
Conclusions:
- Early PMSG administration induces persistent follicular cysts in sheep.
- Luteinization of the theca interna in these cysts results in progesterone production.
- Thecal cells may adopt granulosa cell characteristics under specific luteinizing conditions.