Ultrastructure of spermatozoa from Japanese quail

Abstract

A monoclonal antibody (mAb) to epitopes on mitochondria from turkey spermatozoa cross-reacted with Japanese quail spermatozoal mitochondria. However, the pattern of binding was different from that observed for turkey sperm. The ultrastructure of quail spermatozoa was examined to determine the reason for this difference in antibody binding pattern. Light microscopy, as well as scanning (SEM) and transmission (TEM) electron microscopy, were used to study the morphology of spermatozoa from Japanese quail. Japanese quail had a sauropsid type of sperm cell, which is typical of nonpasserine birds. The spermatozoa were vermiform in shape, with a maximum width of 0.6 microm and an overall length between 230 and 250 microm. An acrosome (3.7 to 4.5 microm), nucleus (20.8 to 23.8 microm), midpiece (160 to 170 microm), and tail (40 to 60 microm) were observed. The TEM showed an acrosomal cap surrounding a perforatorium that inserted into the nucleus at the posterior end. Only a distal centriole was observed, which gave rise to a central axoneme with a 9+2 microtubular structure. The axoneme was encased by a spiraled mitochondrial sheath in the midpiece region (64 to 74% of the overall length of the sperm), and mitochondria numbers were estimated to be greater than 1,400 per sperm. In contrast, turkey sperm contain short midpieces with only 20 to 30 mitochondria per sperm. Differences in binding patterns of the mAb to turkey mitochondria between quail and turkey sperm were due to the presence of mitochondria on the exceptionally long midpieces of quail sperm.

Post-testicular sperm maturation and identification of an epididymal protein in the Japanese quail (Coturnix coturnix japonica)

“…Furthermore, it is known that Japanese quail spermatozoa are heavily reliant on oxidative phosphorylation to support their motility. Indeed, a defining characteristic of these cells is that they possess an exceptionally elongated midpiece (160-170 mm) that accounts for between 64 and 74% of the overall length of the cell (Korn et al 2000). This remarkable structure houses in excess of 1400 mitochondria per sperm, far exceeding the 20-30 mitochondria typically found in other Galliformes such as the turkey and chicken (Thurston & Hess 1987).…”

“…significance of this structural variation is largely unknown, the comparatively high numbers of mitochondria found in quail spermatozoa suggest the requirement for oxidative phosphorylation to supply the demands of ATP generation (Korn et al 2000). In other Galliformes, it is known that sperm oxygen consumption and ATP levels both directly correlated with fertilizing capacity (Wishart 1982, Froman & Feltmann 1998).…”

Induction of sperm acrosome reaction by perivitelline membrane glycoprotein ZP1 in Japanese quail (Coturnix japonica)

“…In order to investigate the AR of quail sperm, we established a method for discriminating acrosome-reacted from acrosome-intact sperm. Since the acrosome in quail sperm is large enough to be visualized under a light microscope (Korn et al 2000), we employed a simple method in which the sperm nucleus was stained with fluorescence DNA dye. As expected, we successfully differentiated between acrosome-reacted and acrosome-intact sperm based on the presence or absence of the acrosome ( Fig.…”

Implementing artificial insemination as an effective tool for ex situ conservation of endangered avian species

“…The midpiece appears to be the most variable component of avian sperm [33], especially in numbers of mitochondria that provide the energy for cellular motility. Although similar in ultrastructural appearance, Japanese quail spermatozoa contain more than 1400 mitochondria, compared to only 20-30 for the turkey [34]. Fowl and turkey spermatozoa have similar morphology and mitochondrial numbers, yet the former are capable of anerobic glycolysis, whereas the latter depend on aerobic oxidation [35].…”

“…The limitation to the intramagnal approach is that it requires substantial operator knowledge and skill; otherwise, the procedure can be overly protracted and stressful. It also circumvents the intense sperm competition within the vagina and permits unfit sperm otherwise expelled by the vagina to populate the upper part of the oviduct [34]. Consequently, duration of fertility is generally no more than 24-48 h depending on species (Blanco, unpublished observations).…”