Hormones: what the testis really sees.

摘要: Various barriers in the testis may prevent hormones from readily reaching cells they are supposed to stimulate, especially hydrophilic pituitary. For example, LH must pass through or between endothelial lining blood vessels reach surface of Leydig cells, and FSH has additional barrier peritubular myoid before it reaches Sertoli cells. The specialised junctions pairs would severely restrict passage peptides luminal fluid therefore inside this barrier, such as later spermatocytes spermatids. There is evidence literature that radioactively labelled does not into blood, concentration native interstitial extracellular surrounding rats only about one-fifth plasma. Furthermore, after injection with LHRH, there large rises within 15 min, at which time have already responded by increasing their content testosterone, but no significant change fluid. Either respond very small changes LH, testicular some way mediate response for now co-cultures lipophilic steroid hormones, produced actions seminiferous tubules also other parts body. They should more than peptides; however, testosterone less testis, stimulation released LHRH despite presence high concentrations an androgen-binding protein. venous rise same extent fluid, suggesting be restriction movement across endothelium. a poor correlation fluids various compartments peripheral Determination whole probably little predictive value, because lipid tend concentrate there, these unlikely any direct effect on testis. best predictor around level collection analysis reasonably simple procedure experimental animals substituted tissue sampling. seems determining peptide vicinity