Pulsatile delivery of progesterone and estradiol to mimic the ovulatory surge in adult ewes by means of TCPL implants.

Tricalcium-phosphate-lysine delivery systems (TCPL) have been developed to release pharmaceuticals into the circulation, at a predictable rate, for prolonged periods of time. The objective of this study was to design an implantable TCPL system capable of delivering progesterone (P) for about two weeks and Estradiol (E) in a short burst that mimics the ovulatory surge in adult ewes. TCPL implants were fabricated in four different sizes (1.

The effect of various testosterone concentrations released from ceramic delivery systems on the circulating hormone levels of adult castrated rams.

Ceramic delivery systems (CDS) have been found to be useful carriers for chemical and biological materials allowing a constant release of these materials over prolonged periods of time. We reasoned that testosterone (TE) filled CDS could be utilized in the long-term treatment of androgen deficient patients. The specific objective of this study was to investigate the ability of CDS to deliver TE at a sustained level for 90 days using castrated adult rams as a model.

The roles of prolactin and testosterone in the development and function of granulosa lutein tissue in the rat.

The luteotropic roles of prolactin and testosterone (or estradiol formed in luteal tissue) were investigated in hypophysectomized rats with homografts of granulosa lutein tissue. Using this approach, we could determine the effects of prolactin independently of estrogen, since granulosa lutein tissue does not produce estrogen de novo under these conditions. Luteinizing granulosa cells were expressed from the ovaries of immature pregnant mare's serum gonadotropin-primed Fischer 344 rats 6 h after injection of human chorionic gonadotropin.

Steroidogenic and morphological characteristics of granulosa and thecal compartments of the differentiating rabbit corpus luteum in culture.

On the day after ovulation, the thecal tissue and associated mural granulosa lutein cells of the rabbit corpus luteum were separated from the granulosa lutein 'core' by dissection and these tissues were cultured separately or together (whole corpus luteum) in defined medium for 10 days on stainless-steel grids. The medium was changed completely every 24 h. Replicate tissues were cultured with testosterone (10 ng/ml), but no other hormones were added to the medium.