Boar spermatozoa develop ability to bind to oviduct epithelium during passage through the epididymis

Peña, Santiago Torda (2007) Boar spermatozoa develop ability to bind to oviduct epithelium during passage through the epididymis. Masters (Research) thesis, James Cook University.

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The aim of this study was to investigate the relationship of maturation of spermatozoa in the epididymis and the ability to bind to oviduct epithelium. It was hypothesized that testicular spermatozoa need to pass through the regions of the epididymis in order to acquire the ability to bind to the oviduct.

Spermatozoa were collected from the rete testis and the caput, corpus and cauda epididymides from 10-14 month-old Large White or Large White x Landrace boars. Boars were first unilaterally castrated and then slaughtered four to five weeks later to obtain the second testicle, epididymis and seminal vesicles. Oviducts were obtained from slaughtered pre-pubertal gilts and explants from the isthmus and ampulla prepared. Spermatozoa were suspended in modified Androhep medium, added to oviduct explants and incubated at 390 C in a humidified atmosphere containing 5% CO2 in air for 15 minutes. The number of spermatozoa attached to 1.25 mm2 of explant was counted after fixation and staining of explants.

The possibility of using oviducts from slaughtered cows rather than porcine oviducts was examined using ejaculated spermatozoa. Significantly more ejaculated spermatozoa bound to the isthmus of gilts than cows hence, porcine oviducts were used in the succeeding experiments. There was a sequential increase in the number of spermatozoa that bound to the oviductal epithelium from the rete testis to the cauda epididymidis (2 ±0.30, 4.36 ±0.53, 9.3 ±1.60 and 15±1.22 for rete testis, caput corpus and caudal spermatozoa on isthmic explants, respectively). Significantly more (P ≤0.05) spermatozoa, either ejaculated or epididymal, bound to isthmus than ampulla explants (26.33±2.27 and 13.55±1.42 ejaculated spermatozoa on isthmic and ampullary explants, respectively).

Incubation in medium containing albumin and asialofetuin which are known to contain mannose and lactose respectively inhibited the binding of epididymal spermatozoa to oviduct explants (3.42±0.56 caudal spermatozoa on isthmic explants in medium with albumin and 14.75±2.02 caudal spermatozoa on isthmic explants in modified Androhep medium).The number of spermatozoa from the caput and corpus that bound to oviduct explants significantly (P ≤0.05) increased after incubation in caudal fluid for 30 minutes (7.52±1.10 and 12.78±1.64 corpus spermatozoa on isthmic explants for modified Androhep and caudal fluid, respectively). This result suggests that caudal fluid has distinct features that directly or indirectly influence the attachment of spermatozoa to oviduct epithelium. The motility of spermatozoa also decreased after incubation in caudal fluid for 30 minutes. This result is not surprising because in vivo, spermatozoa remain in a quiescent state during storage in the cauda epididymidis.

Exposure of epididymal spermatozoa to seminal plasma for 30 minutes significantly reduced the number of spermatozoa that bound to oviduct explants while exposure for one minute significantly increased the number of bound caput spermatozoa. Incubation in seminal plasma also caused capacitation of spermatozoa and this is the likely reason for the reduction in the number of bound spermatozoa. There is also the possibility that some components in the seminal plasma may form a coating over the plasma membrane of spermatozoa sufficient to inhibit the expression of pre-existing binding molecules. On the other hand, the seminal plasma may also be a source of binding molecules for immature caput spermatozoa. There was an increase in the motility of spermatozoa after exposure to seminal plasma.

In conclusion, this study found that as spermatozoa pass down the epididymis, there is an increase in the number of spermatozoa that bind to oviduct explants. This result was interpreted to mean that the maturation of spermatozoa in the epididymis involves the acquisition of the ability to bind to oviduct epithelium.

Item ID: 2007
Item Type: Thesis (Masters (Research))
Keywords: maturation, binding, rete testis, caput, corpus, epididymis, semen, testicular spermatozoa, oviduct epithelium, oviducts, isthmus, ampulla, boars, gilts, sows, pigs, cows, albumin, asialofetuin, Androhep, caudal fluid, motility, spermatogenesis, capacitation
Date Deposited: 16 Dec 2008 23:20
FoR Codes: 07 AGRICULTURAL AND VETERINARY SCIENCES > 0702 Animal Production > 070206 Animal Reproduction @ 0%
06 BIOLOGICAL SCIENCES > 0608 Zoology > 060807 Animal Structure and Function @ 0%
11 MEDICAL AND HEALTH SCIENCES > 1114 Paediatrics and Reproductive Medicine > 111404 Reproduction @ 0%
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