Effect of Dose and Time of Administration of 19-Nortestosterone on the Differentiation of Lymphoid Tissue in the Bursa Fabricii of Chick Embryos

Abstract

Graded doses of 19-nortestosterone, ranging from 0.1 mg to 6 mg, were injected in corn oil solution into the albumin portion of incubating chicken eggs on alternate days between the 5th and 17th days of incubation. Autopsies were performed on the 19th day of incubation. Autopsies were performed on the 19th day of incubation. Body weights, thymus, spleen, adrenal and bursa weights were taken and the tissues fixed and stained. Several of the bursae were analyzed for DNA. A lymph node index was calculated for others. The results indicated that an adequate dose of 19-nortestosterone on any day between the 5th and 17th days of incubation arrested further differentiation. If given prior to the time of plication, the 11th day, the bursa remains as an epithelial sac. A larger dose after this time resulted in pyknotic changes in the epithelium. With increasing doses of the androgen, the DNA levels and lymph node indices decreased. This was associated with an increase in density of the tunica propria. These results tend to support the concept that androgens affect the bursa by inhibiting mitosis in this tissue. The thymus, spleen and adrenal weights were not significantly affected by any treatment.