MODULATION OF OVIDUCT MICROENVIRONMENT FOR PREFERENTIAL BINDING OF X-BEARING SPERMATOZOA IN DAIRY
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Date
2021
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ICAR-SRS-NDRI, KARNAL
Abstract
The present study was undertaken to find out if modulation of micromilieu
of oviductal cells alters the proportion of X- and Y- bearing spermatozoa
binding to oviduct in cattle. As a prerequisite we standardized sperm oviduct
explant binding model for cattle and also standardized a method for denudation
of oviductal monolayer bound spermatozoa. oviductal cells were extruded from
slaughterhouse derived non-luteal oviducts cultured in TCM-199 medium for 12
hours at 5% CO2 and 38.5°C to prepare oviduct explants. Sperm concentration
(2 million), incubation timings (1 hr) and staining method Hoechst 33342 were
standardized for obtaining optimal binding index. Using the standardized sperm
oviduct model, the phenotypic and functional characteristics of oviductal cells
bound and unbound sperm were assessed and found that membrane integrity,
acrosome intactness and mitochondrial membrane potential were significantly
(P<0.05) higher in bound sperm population in comparison with unbound sperm
population. Sperm phenotype characteristics assessment indicated that highfertile
bulls had significantly (P<0.05) higher oviduct explant binding index,
membrane integrity, acrosomal intactness and mitochondrial membrane
potential, and significantly (P<0.05) lower % DNA fragmentation index when
compared to low-fertile bulls. In vivo experiment was conducted on cows (n=20)
to study the effect of oral administration of calcium preparation on sex of the
offspring; out of 6 calves, 5 calves were females. Based on the biochemical
profile assessed in cows (n=6) three doses of calcium (0, 1 and 3 mM),
magnesium (0, 1 and 3 mM) and glucose (0, 1 and 2 mM) were selected for in
vitro modulation, Modulation of oviduct monolayer revealed that calcium at
1mM and 3mM facilitate 15.6 and 5.2 times, respectively more X chromosome
bearing spermatozoa. In contrast, magnesium at 1mM and 3mM facilitated 22
and 37.4 times, respectively more Y chromosome bearing spermatozoa.
However, we did not observe any clear deviation in sex ratio of bound
spermatozoa. it was concluded that sperm phenotypes viz. sperm viability,
acrosome intactness and high mitochondrial membrane potential are
prerequisite characters to bind to oviduct. Further, and incorporation of calcium
in incubation medium skewed sex ratio of oviductal cells bound spermatozoa
towards X-bearing spermatozoa, while incorporation of magnesium skewed the
sex ratio towards Y-bearing spermatozoa.