Effect of (d-Ala6) LHRH on hypophyseal gonadotrophs and ovary of adult frog, Rana tigrina (Daud.) during post-breeding regression phase.

Effects of synthetic luteinizing hormone-releasing hormone (LHRH, 1.5 micrograms) agonist on pituitary and ovary were studied in R. tigrina during November, the post-breeding regression phase. Injections (ip) were given 6 days a week for 30 days and frogs were sacrificed on day 31. Pituitary sections were stained with AB-PAS-OG. The staining intensity, cytoplasmic granulation and cell, nuclear and cytoplasmic areas of hypophyseal gonadotrophs (B2 cells) increased (P < 0.05) following LHRH administration. In controls, the B2 cells were small and faintly stained. LHRH treatment significantly increased ovarian weight over controls due to recruitment of medium sized second growth phase oocytes (MSGP) from the first growth phase (FGP) oocytes. Nearly 50% of oocytes from the FGP oocyte pool were recruited to SGP. Control frog ovaries lacked SGP oocytes. The results demonstrate that both ovary and pituitary of R. tigrina remain responsive to gonadotrophic and GnRH stimulation respectively during the post breeding regression phase.