Localisation of carbonic anhydrase in the sperm storing regions of the domestic hen oviduct.
In the female bird sperm is stored in a quiescent mode, but full motility is needed for successful fertilisation. Regulation of sperm motility is thus of vital interest and the pH is a factor of importance. For this reason the localisation of carbonic anhydrase in the vagina, uterovaginal junction and infundibulum was studied with a histochemical method. Carbonic anhydrase catalyses the reaction CO2 + H2O <--> H+ + HCO3- and is known to take significant part in acid-base regulation in the body. The enzyme was found in all regions with the highest activity, both cytoplasmic and membrane-bound, in the non-ciliated cells of the uterovaginal surface epithelium. Intense membrane-bound activity was also found in the infundibular grooves and glands with slightly less in the sperm storage tubules and vaginal epithelium. Occasionally cytoplasmic and nuclear staining was seen. Changes in pH affect sperm motility and our results provide the first evidence for cellular mechanisms that makes rapid changes of the pH possible in these regions. Judging from the distribution of carbonic anhydrase we suggest two possible functions: (1) increasing pH and/or adding bicarbonate ions to stimulate sperm motility needed for the transfer to the storage sites and at fertilisation, and (2) a lowering of the pH in the sperm storage sites to keep the sperm quiescent during storage.
Holm
L
L
Department of Animal Physiology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Ridderstråle
Y
Y
Knutsson
P G
PG
D000818:Animals; D002256:Carbonic Anhydrases / Q000032:analysis / Q000378:metabolism*; D002645:Chickens / Q000378:metabolism*; D005260:Female; D006651:Histocytochemistry; D006863:Hydrogen-Ion Concentration; D008297:Male; D010057:Oviducts / Q000737:chemistry / Q000166:cytology / Q000201:enzymology*; D013081:Sperm Motility; D013083:Sperm Transport; D013094:Spermatozoa / Q000502:physiology*
D002256:Carbonic Anhydrases