title: Sperm maturation, fluid transport, and secretion and absorption of protein in the epididymis of the echidna, Tachyglossus aculeatus.
abstract: Extratesticular sperm maturation in the echidna mainly occurs in the initial segment of the ductus epididymidis. The process involves the development of motility, migration and loss of the cytoplasmic droplet, a decrease in permeability to Congo red and the formation of sperm bundles. The spermatozoa are supported in the bundles by a matrix of electron-dense material; the bundles are very motile is undiluted samples of luminal fluids. Micropuncture studies of anaesthetized echidnas showed that the ductuli efferentes absorb 74% of the fluid and 46% of the soluble protein that enters them. The initial segment of the ductus epididymidis absorbs 83% of the fluid which enters it, and its secretions increase the concentration of protein in luminal fluid by 107%. Denatured, linear-gradient polyacrylamide gel electrophoresis of micropuncture samples showed that 1 protein (apparent M4 = 100 500) which is not present in blood plasma is present in rete testis fluid, and a glycoprotein which is present in rete testis fluid (apparent Mr = 78500) is absorbed by the ductuli efferentes. Six proteins which are not present in blood plasma are secreted into the initial segment of the ductus epididymidis; 5 are glycoproteins (apparent Mr = 48500, 39000, 32000, 20500 and 19000) and one (apparent Mr = 82500) is not. The most prominent electrophoresis bands corresponded to the glycoproteins with apparent molecular weights of 48500, 20500 and 19000.
mesh_terms: D000818:Animals; D004591:Electrophoresis, Polyacrylamide Gel; D004822:Epididymis / Q000378:metabolism / Q000502:physiology*; D008297:Male; D008970:Molecular Weight; D009007:Monotremata / Q000502:physiology*; D011506:Proteins / Q000378:metabolism*; D013079:Sperm Maturation; D013083:Sperm Transport; D004442:Tachyglossidae / Q000502:physiology*
chemical_list: D011506:Proteins