Comparative anatomy of the tubo‐uterine junction. Histology and physiology in the sow

109

Summary. Fine thermistor probes positioned in each end of the same oviduct and connected to the same scale were used to measure temperature gradients in the lumen before and after spontaneous ovulation in normally-cyclic gilts. Readings were taken after full surgical closure of a mid-ventral incision and a subsequent period of stabilization, but whilst animals remained under general anaesthesia.A small but consistent difference in temperature was recorded between the proximal ampulla and distal isthmus of the same oviduct in each of 20 preovulatory gilts. In 10 of these animals that had not mated, the isthmus was a mean of 0\m=.\43\s=deg\Ccooler than the ampulla (range 0\ m=. \ 2\ p=n-\ 0\ m=. \ 7\ s=deg\ C whereas in 10 mated animals the isthmus was 0\m=.\69\s=deg\Ccooler (range 0\ m=. \ 2\ p=n-\ 1\ m=. \ 6\ s=deg\ C 3 animals in the latter group had within-oviduct differences of \ m=ge\ 1\s=deg\C. By contrast, in 12 animals that had recently ovulated, the isthmus was a mean of only 0\ m=. \ 1\ s=deg\ Ccooler than the ampulla; there was no measurable temperature gradient in 3 of the animals, whilst the isthmus was 0\ m=. \ 1\ s=deg\ C warmer in 2 animals. The preovulatory temperature differences are thought primarily to reflect the extent and activity of the vascular and lymphatic beds in the oviduct tissues and, together with specific chemical microenvironments, may facilitate the relatively prolonged period of sperm storage in the distal portion of the isthmus.

Section: Resultsmentioning

confidence: 43%

A preovulatory temperature gradient between the isthmus and ampulla of pig oviducts during the phase of sperm storage

Hunter¹,

Nichol²

1986

109

“…In response to the first question, the lumen of the oviduct isthmus is extremely narrow in oestrous animals, in part due to the oedematous condition of the mucosal folds (Andersen, 1928 ; Lee, 1928 ;Hunter, 1973), and passage of spermatozoa would be impeded on physical grounds alone. Special consideration must also be given to the myosalpinx.…”

Section: Discussionmentioning

confidence: 42%

Pre-ovulatory arrest and peri-ovulatory redistribution of competent spermatozoa in the isthmus of the pig oviduct

Hunter¹

1984

154

Summary. Using the surgical approach of post-coital ligation and transection of the distal oviduct at different times relative to ovulation, together with subsequent recovery of the eggs, gilts mated at the onset of oestrus were studied for progression of viable spermatozoa within the isthmus. Results are derived from 76 animals and examination of 1047 eggs.Transection of the isthmus 1\ m=. \ 5\ p=n-\ 2\ m=. \ 0cm proximal to the utero-tubal junction at intervals from 3 to 36 h after mating prevented fertilization in 269 of 270 eggs, whereas 98% of 223 eggs were fertilized in the control oviducts. Transection at 38 h ( pr e\ x=r eq-\ ovulatory), 40 h (peri-ovulatory) and 42\p=n-\44 h (post-ovulatory) after mating yielded, respectively, 5%, 40% and 100% fertilization. The mean number of spermatozoa associated with the zona pellucida increased in a parallel manner. These results, and those obtained with ligatures placed closer to the site of fertilization just after ovulation, indicate a pre-ovulatory arrest of viable spermatozoa in the caudal region of the isthmus for 36 h or more followed by an active ad-ovarian redistribution.

“…The manner whereby such injections influence the occurrence of polyspermy has still to be resolved conclusively, but the concept of an alteration in the tubai environment permitting increased numbers of competent spermatozoa to ascend to the site of fertilization is thought to be of prime importance. Cyclic changes in the tissues of the isthmus and the uterotubal junction have been reported by Andersen (1928), these regions being constricted and oedematous during oestrus, so that the passage of excessive numbers of spermatozoa to the ampulla would be impeded. By contrast, relaxation of these tissues takes place during the luteal phase of the oestrous cycle under the influence of endogenous progesterone, and a similar modification is presumed to occur after the local injections of progesterone (see Hunter & Léglise, 1971).…”

Section: Discussionmentioning

confidence: 42%

Local Action of Progesterone Leading to Polyspermic Fertilization in Pigs

Hunter¹

1972

Polyspermic fertilization was found in 32\m=.\3% of the eggs recovered from the progesterone-treated tubes compared with 9\m=.\7% of those from the control tubes (P<0\m=.\01). The number of tubes yielding polyspermic eggs was also significantly higher on the progesterone-treated side (P<0\m=.\01).Injection of progesterone 8 hr before ovulation resulted in 38\m=.\2%polyspermic eggs from the treated tubes, dispermy being the principal anomaly of fertilization. In both dispermic and trispermic eggs, the female and a single male pronucleus were uniting, the accessory male element(s) remaining in the opposite hemisphere of the egg.It is concluded that relaxation of the oedematous tissues of the isthmus and uterotubal junction occurs after local injection of progesterone. In these circumstances, polyspermy is thought to originate principally from increased numbers of spermatozoa reaching the site of fertilization, although a direct effect of progesterone on the membranes of the gametes cannot be excluded. The disposition of the accessory male pronuclei in the polyspermic eggs raises the question whether polyploids usually arise from polyspermy or whether delayed cleavage and cytoplasmic fragmentation are more frequent sequelae to this condition in pigs.