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L. M. Harrison, N. Kenny and G. D. Niswender

Summary. Corpora lutea were collected from sheep on Days 6,10, and 15 of the oestrous cycle and Day 25 of pregnancy and dissociated into single cell suspensions. Purified preparations of large and small luteal cells were prepared by elutriation on all days except Day 6. Basal progesterone production by large cells was 6–8-fold higher than by small cells (36–65 vs 6–9 fg/cell/min). Oxytocin secretion was maximal on Day 6(1·0 fg/cell/min) and declined thereafter. The number of receptors for LH increased between Day 6 and Day 10 and the two cell types had an equal number of receptors on Days 10 and 15 (19 000–23 000). Large cells on Day 25 of pregnancy had fewer receptors (12 000) than did small cells (26 000). Progesterone secretion by small luteal cells from all days examined was stimulated by LH (0·01–1000ng/ml) in a dose-dependent manner; maximum sensitivity to LH occurred on Day 10. Despite the presence of receptors for LH on large cells, LH failed to stimulate progesterone production. Basal production of progesterone by large and small cells, and the response of small cells to LH, was not influenced by day examined. Re-combinations of large and small cells from Day 10 synergized to increase progesterone secretion. Prostaglandin E-2 (0·1–1000 ng/ml) did not stimulate progesterone secretion by large or small cells.

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W. C. L. Ford, Anne Harrison and G. M. H. Waites

Summary. 6-Chloro-6-deoxyfructose or 6-chloro-6-deoxyglucitol (>90 μmol/kg/ day), 6-chloro-6-deoxyglucose or 6-chloro-6-deoxymannose (>120 μmol/kg/day) and 6-chloro-6-deoxygalactose (>300 μmol/kg/day) all had an antifertility action in the male rat when given by mouth. Spermatozoa from the infertile rats were unable to oxidize glucose. This effect was always produced by a lower dose than the antifertility effect and the threshold dose for the 2 effects varied in a parallel fashion between the different 6-chloro-6-deoxysugars. Glucose oxidation appeared to be inhibited at the triose phosphate isomerase or glyceraldehyde 3-phosphate dehydrogenase reaction. These effects of 6-chloro-6-deoxysugars are similar to those of α-chlorohydrin.

The activities of the glycolytic enzymes were greatly in excess of the observed flux through the pathway and high concentrations of glucose 6-phosphate and triose phosphate accumulated in rat spermatozoa incubated with 2 mm-d-glucose.

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W. C. L. Ford, Anne Harrison and G. M. H. Waites

Summary. When 0·1 mM-S α-chlorohydrin was present in incubations, glycolysis by ram testicular spermatozoa was almost completely inhibited whereas 10 mM-R α-chlorohydrin had no effect. Male rats dosed orally with S α-chlorohydrin (3·25 mg/kg/day) became much less fertile than controls but those dosed with R α-chlorohydrin (13 mg/kg/day) did not. The loss of fertility was associated with a reduced ability of spermatozoa from the cauda epididymidis of these rats to oxidize glucose. It is concluded that the S enantiomer is responsible for both the inhibition of sperm glycolysis and the reduction in fertility caused by the racemic mixture of α-chlorohydrin.