Sperm Tracking Research Articles

Relationship between the length of sperm preincubation and zona penetration in the golden hamster: A scanning electron microscopy study

AbstractHamster spermatozoa are able to fertilize a high percentage of zona‐intact hamster oocytes when they are preincubated for 2 hr in a chemically defined medium. From this time on, the longer the preincubation time the lower the percentage penetration. Spermatozoa preincubated for 6 or more hr are unable to cross the zona pellucida, retaining however their ability to fuse with zona‐free hamster oocytes.Zona‐intact hamster oocytes, as described above, were observed with the scanning electron microscope. When the oocytes were inseminated with spermatozoa preincubated for 1 to 5 hr the outer surface of the zona showed the penetrating spermatozoa and the sperm tracks made by those that failed to cross it. With longer preincubation times no penetrating spermatozoa were observed, and very few sperm tracks were present on the outer surface of the zona.Control experiments showed that neither eggs, spermatozoa, nor fertilization were affected by the medium recovered after long preincubations.These results show that care should be taken regarding the preincubation time when using the in‐vitro fertilization technique.

A correlation between a spectrophotometric quantitation of rabbit spermatozoan motility and velocity.

Rabbit sperm motility was measured spectrophotometrically and a sperm motility index (SMI) was obtained. A comparative analysis between the SMI values and the velocity of motile sperm (obtained by time lapse photography of sperm tracks) was performed. The SMI specifically was compared to the mean velocity of the first 300 sperm cells observed and to the mean velocity of just the first 300 progressively motile sperm cells. In both comparisons, the SMI was highly correlated to the sperm track length (sperm velocity). In addition, a modification of the spectrophotometric procedure is described which allows measurements of the SMI to be made on semen extended into egg-yolk glycerine cryopreservation agents.

Cytological Investigations On the Male Reproductive System and the Sperm Track in the Spider Mite Tetranychus Urticae Koch (Tetranychidae, Acarina)

The post-embryonic development of the male internal genitalia, the development and production of the male germ cells, and the sperm track in the female of the two-spotted spider mite Tetranychus urticae Koch has been described. The male reproductive system consists of a testis, two vesiculae seminalis, a sperm pump, a ductus ejaculatorius and an aedeagus. The testis is a single structure in the larva, but during the nymphal stages it is generally divided into a right and a left half. The vesiculae seminalis develop from groups of cells which lie, in the larva, against the lateral sides of an epidermal invagination underneath the testis. In adults the vesiculae are provided with vesicular compartments which originate from the sheath cells. The sperm pump differentiates from the distal part of the invagination and some cells surrounding the latter. The remainder of the invagination forms the ductus ejaculatorius and aedeagus. The germ cells multiply by asynchronous spermatogonial mitoses. They are haploid with three chromosomes. Spermatocytes were not observed, which means a complete reduction of the meiosis. Spermatid formation begins at the nymphochrysalis stage and spermatozoa are found already at the deutochrysalis stage. During spermiogenesis the chromosomes lie in a line suggesting a non-random distribution in the sperm nucleus. The ripe spermatozoon is a spherical nucleus surrounded by two layers of plasm. A nuclear membrane and mitochondria were not observed. Germ cell production is continuous during the lifetime of the male, whether the males copulate or not. The numbers of the various germ cells vary dependent on the stage of life. The numbers of spermatozoa in the vesiculae seminalis and the sperm pump vary considerably, even if copulation does not take place. The numbers do not decrease during the first eight days of adulthood. The males produce an excess of spermatozoa. Ejaculations without copulation may take place. During copulation the spermatozoa are transferred behind each other with the aid of the sperm pump and may then become long-drawn because of a narrow ductus ejaculatorius or a narrow penial canal. One normal insemination supplies the female with a sufficient number of spermatozoa. The entrance to the receptaculum seminis is a short narrow tube which runs from an opening in the epidermis behind the genital opening. The receptaculum is situated posterior to the exit ducts of the ovarium and consists of about forty cells surrounding a lumen. Immediately after copulation spermatozoa are in the lumen and the basal parts of the cells. They may thus be transformed, though recovery takes place, and may adhere together forming packets. They migrate through the cells towards the haemolymph, which may take place within one day. Under influence of the growth of the oocytes and the movements of the mature eggs single spermatozoa are transported in the haemolymph towards the oocytes.