http://directory.umm.ac.id/Data%20Elmu/jurnal/A/Animal%20Reproduction%20Science/Vol60-61.Issue1-4.Jul2000/1971.pdf

The causes of reduced fertility with cryopreserved semen

At coitus, human sperm are deposited into the anterior vagina, where, to avoid vaginal acid and immune responses, they quickly contact cervical mucus and enter the cervix. Cervical mucus filters out sperm with poor morphology and motility and as such only a minority of ejaculated sperm actually enter the cervix. In the uterus, muscular contractions may enhance passage of sperm through the uterine cavity. A few thousand sperm swim through the uterotubal junctions to reach the Fallopian tubes (uterine tubes, oviducts) where sperm are stored in a reservoir, or at least maintained in a fertile state, by interacting with endosalpingeal (oviductal) epithelium. As the time of ovulation approaches, sperm become capacitated and hyperactivated, which enables them to proceed towards the tubal ampulla. Sperm may be guided to the oocyte by a combination of thermotaxis and chemotaxis. Motility hyperactivation assists sperm in penetrating mucus in the tubes and the cumulus oophorus and zona pellucida of the oocyte, so that they may finally fuse with the oocyte plasma membrane. Knowledge of the biology of sperm transport can inspire improvements in artificial insemination, IVF, the diagnosis of infertility and the development of contraceptives.

/pdf/sperm-transport-in-the-female-reproductive-tract-1wd76o2ooi.pdf

Sperm transport in the female reproductive tract

In the present study, we provide evidence for the production of reactive oxygen species (ROS) during cryopreservation of bovine spermatozoa. Cooling and thawing of spermatozoa cause an increase in the generation of superoxide radicals. Although nitric oxide production remains unaltered during sperm cooling from 22-4 degrees C, a sudden burst of nitric oxide radicals is observed during thawing. Increase in lipid peroxidation levels have been observed in frozen/thawed spermatozoa and appears to be associated with a reduction in sperm membrane fluidity as detected by spin labeling studies. The data presented provide strong evidence that oxygen free radicals are produced during freezing and thawing of bovine spermatozoa and suggest that these reactive oxygen species may be a cause for the decrease in sperm function following cryopreservation. Mol. Reprod. Dev. 59: 451-458, 2001.

Production of reactive oxygen species by spermatozoa undergoing cooling, freezing, and thawing.

http://directory.umm.ac.id/Data%20Elmu/jurnal/A/Animal%20Reproduction%20Science/Vol62.Issue1-3.Aug2000/2026.pdf

Storage of bovine semen in liquid and frozen state

This paper highlights the most critical aspects of the problem of predicting fertility. To determine if a laboratory test(s) is highly correlated with fertility it is essential to have: a) specific, precise and accurate laboratory tests, and b) precise and accurate fertility data. Acquisition of precise and accurate data for laboratory tests and fertility of spermatozoa in the same sample is not easy. Data derived from in vitro fertilization are not tests of fertility, because only a subset of the attributes important for fertilization in vivo are tested. Because of deficiencies in fertility data, there probably is no valid report for human spermatozoa correlating results of laboratory tests and fertility, and very few valid studies for laboratory or domesticated animals. There is little doubt that objective measures of sperm motion, acrosomal status, or other characteristics are significantly correlated with fertility. However, establishment of the correlations between a group of attributes and fertility is not the question of interest. The goal is prediction of fertility. There has been no recent effort to develop a prediction of fertility or fecundity based on sperm characteristics, and achievement of this goal may be elusive.

M. Kaproth

Papers

A specific oligoteratozoospermia in a bull: The sperm tail stump defect

Antibiotics for Bull Semen Frozen in Milk and Egg Yolk Extenders

Semen quality and behavior of Holstein bulls exposed to estradiol-treated bulls for mounts.

Assessing cryocapacitation in frozen-thawed bovine sperm from a commercial bull stud

Postthaw motility, acrosomal integrity, and fertility of antibiotic-treated frozen bull spermatozoa