The present study describes the measurement of pH made in vivo in the rete testis fluid and in different regions of the boar epididymis. Furthermore, samples of whole ejaculates, semen fractions, testicular (ductuli efferents/rete testis), epididymal and deferential fluids collected from the same fertile boars, were analysed for their acid/base status with an automatic blood gas analyser. A pH gradient of activity was found between the fluid entering the ductus epididymis (pH 7.2) and the region of sperm storage at the cauda (pH 6.5). A significantly lower concentration of bicarbonate ion was found in the cauda epididymidis (3-4 mM) compared to rete testis fluid (30 mM), which might be related to the quiescence of the spermatozoa. A significant increase in extracellular pH and bicarbonate concentration occurred at ejaculation, the bicarbonate levels being 9-10-fold higher in the semen fraction rich in seminal vesicle fluid, where sperm showed higher motility, than in the cauda epididymis.
Spermatozoa are subjected to major changes as they pass through the epididymal duct. The aim of the present study was to describe the distribution of carbonic anhydrase (CA) in the mouse testis and epididymis using a histochemical technique showing total catalytic activity, in combination with immunohistochemistry for the two important isoforms CAs II and IV. By comparing normal mice with CA II-deficient mice, we were able to study membrane-bound CA without influence from the ubiquitous cytoplasmic CA II. Spermatozoa, when studied in both the scanning electron and light microscope, were found to pickup membrane-bound CA IV during their passage through the epididymal duct. The transfer appeared to take place in the proximal part of the corpus, where the apical membrane and vesicles of principal cells were richly supplied with CA IV. In addition to CA IV, another membrane-bound isozyme was located in basolateral membranes of principal cells. Cytoplasmic CA II was found in varying amounts in apical/narrow cells and principal cells of the corpus in control animals. The significance of CA for pH-regulating processes vital for sperm storage and motility is discussed. A function in HCO3- transport during sperm capacitation at fertilization is suggested for the CA IV found in spermatozoa.
The fine structure of spermatogenesis and Sertoli cells in bulls has been described. New observations and data from the literature have been compiled to give a comprehensive description of the complicated differentiation processes and cellular relations in the seminiferous epithelium.
The ovaries and internal genital tracts of cycling gilts were studied for localization of carbonic anhydrase activity using a post-embedding cobalt precipitation technique. Carbonic anhydrase activity was present in selective capillary endothelia and epithelial cells of the genitalia. The ovarian parenchyma, irrespective of the stage of the oestrous cycle considered, was unstained. The secretory cells of the deep furrows in the uterotubal junction and those in the isthmic region of the oviduct of the oestrous female showed a clear membrane-bound localization. The surface epithelium in the tubal ampulla showed a conspicuous cytoplasmic carbonic anhydrase activity during oestrus and the early luteal phase. Neither the intensity nor the localization of the histo-enzymatic reaction in the females varied with their hormonal status (i.e. stage of the oestrous cycle). The localization of the enzyme in particular regions of the female pig genitalia that normally act as sperm reservoirs (uterotubal junction – tubal isthmus) or where fertilization – early embryo development occur (i.e. ampulla) might be related to the control of the acid-base status of the luminal fluid.
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