Aa. Grippo et al., CHOLESTEROL, PHOSPHOLIPID AND PHOSPHOLIPASE-ACTIVITY OF AMPULLARY ANDISTHMIC FLUID FROM THE BOVINE OVIDUCT, Journal of Reproduction and Fertility, 102(1), 1994, pp. 87-93
Cholesterol and phospholipid concentrations and phospholipase activity
were measured in fluid from cannulae collected from the bovine oviduc
tal isthmus and ampulla at different stages of the oestrous cycle. The
cholesterol concentration and cholesterol normalized by protein were
significantly (P = 0.03) greater in isthmic oviductal fluid (224.3 +/-
42.7 mu g ml(-1) over all stages) than in ampullary oviductal fluid (
164.5 +/- 11.3 mu g ml(-1)), and maximal concentrations (284.5 +/- 125
.5 mu g ml(-1)) were found during the luteal stage (serum progesterone
concentration greater than or equal to 1.5 ng ml(-1)). The concentrat
ions of the phospholipids sphingomyelin and lysophosphatidylcholine in
creased at different stages of the cycle and in different regions. In
the ampulla, the concentration of sphingomyelin was significantly (P <
0.05) greater in oviductal fluid collected during the luteal phase (1
2.1 +/- 2.7% of total phospholipids) than in fluid collected near oest
rus and ovulation (7.5 +/- 1.5% and 6.9 +/- 1%, respectively). The con
centration of lysophosphatidylcholine was greater (P < 0.01) in ampull
ary (19.2 +/- 1.6% of total phospholipids) than in isthmic oviductal f
luid (9.9 +/- 1.1%) collected near ovulation. The ratio of cholesterol
to total phospholipid was highest in oviductal fluid collected from t
he isthmus during all stages (2.3 mu g ml(-1):% total phospholipid), w
hile the minimal ratio was found in ampullary fluid collected near ovu
lation (1.5). Phospholipase activity was higher (P = 0.03) in isthmic
oviductal fluid (20.4 +/- 3.2% product formed) than in ampullary ovidu
ctal fluid (14.6 +/- 1.4%); the lowest activity (12.6 +/- 1.7% product
formed) was in fluid collected during the phase of the oestrous cycle
immediately before ovulation. We conclude that the regional and tempo
ral differences in the concentrations of lipids in oviductal fluid pro
vide general support for the concept that the isthmus serves as a sper
m reservoir, while the ampulla is the site of the bovine sperm acrosom
e reaction.