Importance of sperm morphology during sperm transport and fertilization in mammals

Abstract

After natural or artificial insemination, the spermatozoon starts a journey from the site of deposition to the place of fertilization. However, only a small subset of the spermatozoa deposited achieves their goal: to reach and fertilize the egg. Factors involved in controlling sperm transport and fertilization include the female reproductive tract environment, cell-cell interactions, gene expression, and phenotypic sperm traits. Some of the significant determinants of fertilization are known (i.e., motility or DNA status), but many sperm traits are still indecipherable. One example is the influence of sperm dimensions and shape upon transport within the female genital tract towards the oocyte. Biophysical associations between sperm size and motility may influence the progression of spermatozoa through the female reproductive tract, but uncertainties remain concerning how sperm morphology influences the fertilization process, and whether only the sperm dimensions per se are involved. Moreover, such explanations do not allow the possibility that the female tract is capable of distinguishing fertile spermatozoa on the basis of their morphology, as seems to be the case with biochemical, molecular, and genetic properties. This review focuses on the influence of sperm size and shape in evolution and their putative role in sperm transport and selection within the uterus and the ability to fertilize the oocyte.

Proteome of the periovulatory oviduct and uterus of goats as related to nutritional balance

“…Sperm transport, capacitation and fertilization are complex processes that are affected by several factors, including the environment of the female reproductive tract (García‐Vázquez et al, ). Problems related to spermatic transport are usually associated with immobilization and death in the uterus after ejaculation or insemination (Hawk, ).…”

“…The initial development of the embryo and the subsequent establishment of pregnancy is complex processes that require a receptive endometrium, a functional embryo and a synchronized dialog between maternal (oviduct and uterus) and embryonic tissues (Dixon et al, ). Pregnancy loss occurs due to sperm inability to properly fertilize the oocyte (García‐Vázquez, Gadea, Matás, & Holt, ), failure in the embryo initial development (Dixon et al, ) and deregulation asynchrony of the maternal reproductive tract, caused by changes in histotrophic nutrition which is synthesized and secreted by the glandular epithelium during the periovulatory period (Koch, Ramadoss, & Magness, ).…”

An update of the regulatory factors of sperm migration from the uterus into the oviduct by genetically manipulated mice

“…Although the structure of the UTJ varies substantially among different mammalian species, this passageway is usually narrow (Fujihara, Miyata, et al, 2018;Suarez & Pacey, 2006). The number of sperm that passes through the UTJ is markedly reduced before reaching the oviduct ampulla either in humans or mice (Garcia-Vazquez, Gadea, Matas, & Holt, 2016). It has also been proposed that most sperms swim up through the UTJ into the oviduct by self-propulsion (Ikawa et al, 2010;Ishikawa, Usui, Yamashita, Kanemori, & Baba, 2016;Okabe, 2015).…”

Comparison of the structure of chinchilla sperm isolated from semen and from the tail of the epididymis

“…Gómez Montoto et al () suggest that an increase in sperm velocity in rodents was associated with more elongated heads, which is also supported by research by Malo et al (). According to some authors (Fitzpatrick, Garcia‐Gonzalez, & Evans, ; Gomendio & Roldan, ), the shape of the sperm head affects its hydrodynamics in the female reproductive tract, and sperm with longer tails have a greater fertilization capacity due to increased motility (García‐Vázquez, Gadea, Matás, & Holt, ; García‐Vázquez et al, ; Partyka, Niżański, & Ochota, ). Assessment of the mitochondria and midpiece during semen analysis may therefore be useful as a marker of sperm fertility (Gallon, Marchetti, Jouy, & Marchetti, ).…”