Uterine secretion of fructose in the roe deer

Abstract

The roe deer is the only ungulate known to exhibit the phenomenon of delayed implantation. Shortly after ovulation in early August, the blastocyst loses its zona pellucida and enters a 5-month period of diapause during which the trophoblast exhibits a minimum of mitotic activity and the inner cell mass remains undifferentiated. Delayed implantation is terminated in early January by the sudden, rapid elongation of the trophoblast and subsequent placental attachment (Short & Hay, 1966). The resumption of rapid embryonic growth appears to coincide with the release of a secretion from the endometrial glands (Aitken et al., 1973;Aitken, 1975 Eighty-five roe deer shot during the annual Forestry Commission cull at Thetford Chase, Norfolk, provided the material for this study. The uterus was removed from each animal immediately after death and kept on ice for about 1\ m=1/ 2\ hr while being transported to a field laboratory. The uterine horns were then separated and flushed with 20 ml 0-85% phosphate-buffered saline (Aitken, 1974). The carbohydrate content of the flushings was determined with anthrone (Trevelyan & Harrison, 1952), and the ethanol-soluble sugars were analysed by thin-layer chromatography on silica-gel plates employing the solvent system, 1-butanol:acetic acid:diethyl ether:water (9:6:3:1 by vol.) (Hay, Lewis & Smith, 1963). Thymol was used as a locating reagent (Adachi, 1965), and the presence of ketose sugars was confirmed with anthrone (Johanson, 1953), ß-indolylacetic acid (Heyrovsky, 1956), dimedone (Adachi, 1964) and phloroglucinol (Menzies & Seakins, 1969). Endometrial homogenates were prepared by homogenizing 1-2-1-9 g of tissue in 15 ml cold 0-85% phosphate-buffered saline. Proteins were precipitated with alkaline ZnS04 and the fructose content of the supernatant estimated with resorcinol (Mann, 1948). (5) The results revealed a highly significant (P<0-001 ; t test) increase in the carbohydrate content of the uterine flushings upon the resumption of rapid embryonic growth (Table 1). Thin-layer chromato¬ graphy of the flushings revealed the presence of a single hexose in 18 samples collected at the time of rapid embryonic growth which was absent from another 12 flushings obtained during diapause. This sugar migrated with fructose on TLC, gave positive ketose and Seliwanoff reactions, reduced Benedict's solution and was dialysable (12 samples). It was concluded that the sugar was free fructose. Fructose was also detected in the endometrium during diapause (65-05±17-37 (S.D.) pg/g wet weight, N=7) and in a single sample obtained at the time of embryonic elongation (46-21 pg/g wet weight). The fetal fluids of rapidly elongating embryos also contained fructose both before and after placental attachment. Contamination of the flushings with fructose-rich fetal fluids was believed to be minimal, since this sugar was also detected in the non-gravid horn of unilaterally pregnant animals.

Endometrial luminal epithelial cells sense embryo elongation in the roe deer independent of interferon-tau†

“…We hypothesize that a decrease in expression of SLC5A1 takes place prior to elongation, where the embryo has an increased demand of glucose. The latter has been determined earlier in the uterine fluid of developing roe deer embryos [14].…”

“…The roe deer is the only known ungulate that displays embryonic diapause. Changes between diapause and embryo elongation in uterine fluid constituents have been described, i.e., a rise in hexose, fructose, total protein, αamino nitrogen, and calcium [12][13][14]. The corpus luteum remains active during the entire period of embryonic diapause and embryo elongation.…”

“…By using a holistic proteomics approach, we have previously shown that the roe deer embryo at diapause faces an environment with high cellular detoxification, and that there is an increased abundance of proliferation-inducing proteins at elongation [16]. During embryo reactivation, no concentration changes have been shown for classical ungulate embryonic MRP signals such as IFNτ , estrogens, or chorionic gonadotropins, and for the maternal signals for embryo reactivation such as prolactin, P4, and estrogens [12][13][14][15][17][18][19].…”

Uterine fluid proteome changes during diapause and resumption of embryo development in roe deer (Capreolus capreolus)

“…These secretions were found to be up to 1.5-fold increased during implantation compared to diapause (Aitken et al 1973, Lambert 1999). A first exploratory analysis of the biochemical nature of the uterine fluid during elongation showed a rise in hexose, fructose, total protein, α-amino nitrogen and calcium concentration (Aitken 1974 a , b , 1976). However, there was no association between elongation and secretion of zinc, glucose and prostaglandin F 2α (Aitken 1974 a , b ).…”

Ovarian histology and hormonal activity of roe deer fawns

“…Rapid development of the embryo begins the mid-January continuing to the moment of parturition in late May (Raesfeld, 1960). According to Aitken (1976) this phase of rapid growth is associated with intensive fructose secretions from the uterine glands.…”