Components of oviduct physiology in eutherian mammals

Abstract

Recalling the evolutionary sequence of development first of gonad and subsequently of oviducts, ovarian endocrine regulation of all known components of oviduct physiology is reviewed. Ovaries not only influence oviducts via the systemic blood circulation, but also locally by counter-current transfer of relatively high concentrations of steroid hormones and prostaglandins between the ovarian vein and oviduct branch of the ovarian artery. The efficiency and impact of such counter-current transfer is greatest around the time of ovulation, the transfer process receiving further inputs from hormones present in peritoneal fluid. Classical oviduct physiology is summarised, and the potential molecular consequences of temperature gradients within the duct lumen examined. At ovulation, an oocyte-cumulus complex is displaced in minutes from the follicular surface to the site of fertilisation at the ampullary-isthmic junction of the oviduct. This rapid initial phase is contrasted with the subsequent slow progression of embryos to the uterus in days, still encompassed within a zona pellucida. Regarding transport of spermatozoa, the formation of a pre-ovulatory reservoir in the caudal portion of the oviduct isthmus is noted, with suppression of motility and sperm-head binding to epithelial organelles acting to maintain fertilising ability. Completion of capacitation is prompted shortly before ovulation, predominantly by Ca(2+) influx into bound spermatozoa. A controlled release of spermatozoa coupled with their hyperactivation results in initial sperm:egg ratios at the site of fertilisation close to unity, thereby avoiding the pathological condition of polyspermy. Both the oviduct milieu and embryonic development are influenced by paracrine activity of follicular granulosa cells released at ovulation and remaining in suspension in the vicinity of the oocyte or embryo. These cells may amplify early pregnancy signals from a zygote to the endosalpinx. Beneficial effects of the oviduct on domestic animal embryos are contrasted with anomalies arising as a consequence of in vitro culture. Primate embryos do not require exposure to an oviduct for normal development, perhaps due to overlapping compositions of endosalpingeal and endometrial secretions. Additionally, primate endometrial secretions may be modified by viable gametes or an embryo in the presence of a cumulus cell suspension.

Influência das secreções de células do oviduto cultivadas in vitro sobre a viabilidade de espermatozoides bovinos congelados-descongelados

“…Após a última lavagem, o precipitado foi transferido para garrafas de cultivo celular de 25 cm 2 que continham 5,0 ml de meio tcm 199 sem Hepes suplementado com 100 U/ml de nistatina, 50 µg/ml de gentamicina, 100 U/ml de penicilina G, 100 µg/ml de estreptomicina e com 10 % de sfb. Foram mantidas em estufa incubadora a 5 % de co 2 , umidade saturada e temperatura de 38,5°C por um período de cinco dias.…”

“…O sobrenadante foi descartado e o precipitado ressuspenso em 5ml de Talp-spLavagem (meio Talp acrescido de 0,2 mM de piruvato de sódio, 100 UI/ml de penicilina G, 100 µg/ml de estreptomicina e 0,01 g de pva, previamente estabilizado por três horas em estufa incubadora a 5 % de co 2 , 38,5°C e umidade saturada). Em seguida, foi realizada uma centrifugação a 150 X g por três minutos.…”

“…O microambiente produzido pela secreção das células da mucosa do oviduto atua positivamente sobre a motilidade espermática, reação acrossômica e habilidade para fertilizar o ovócito [1,2].…”

Expression of 3β-hydroxysteroid dehydrogenase and P450 aromatase in porcine oviduct during the oestrous cycle

“…Steroid hormones, mainly progesterone (P4) and oestradiol-17β (E2), affect oviduct functioning in pigs and other species (Hunter, 1991(Hunter, , 2012Hunter et al, 1999;Chen et al, 2013). These steroids affect gene expression, cells ultrastructure and differentiation, motility of oviduct, as well as the composition and volume of oviductal fluid during the oestrous cycle (Rodriguez-Martinez et al, 1982;Buhi, 2002;Yaniz et al, 2006;Carrasco et al, 2008;Skowronski et al, 2011;Hunter, 2012).…”

“…These steroids affect gene expression, cells ultrastructure and differentiation, motility of oviduct, as well as the composition and volume of oviductal fluid during the oestrous cycle (Rodriguez-Martinez et al, 1982;Buhi, 2002;Yaniz et al, 2006;Carrasco et al, 2008;Skowronski et al, 2011;Hunter, 2012). Thus, steroids regulate oviductal microenvironment and support maturation of gametes, fertilization and early embryonic development (Hunter et al, 1999;Wollenhaupt et al, 2001;Buhi, 2002;Georgiou et al, 2005;Brüssow et al, 2008;Chen et al, 2013).…”