CHANGES IN INSULIN AND PROLACTIN RESPONSIVENESS OF GOAT MAMMARY TISSUE DURING ONTOGENESIS AND PREGNANCY

  • 1 January 1978
    • journal article
    • research article
    • Vol. 12  (4) , 217-232
Abstract
Mammary tissue of goats in different stages of ontogenesis and pregnancy were organ-cultured. Their insulin and prolactin responsiveness was studied. Based on the synthesis of DNA in the presence of insulin and tissue secretory responses to prolactin, the responsive tissues were found in young goats up to age 3 mo. (prolactin responsive only up to age 24 days), in mature virgin goats at the end of breeding season, mature virgin goats with precocious lactation and in nulliparous goats from the 8th wk of pregnancy. Unresponsive tissues were found in goats from age 4 1/2 mo. to maturity. The high number of antral follicles in goat ovaries was coincident with high mammary insulin and prolactin responsiveness during ontogenesis. Ovarian and placental steroids and placental lactogen render the goat mammary tissue responsive to insulin and prolactin in organ culture.

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