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 micro/m), 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.

Recent advances in bird sperm morphometric analysis and its role in male gamete characterization and reproduction technologies

“…Detailed electron microscope-based information is available on the appearance, measurements, and classification of normal and defective chicken spermatozoa,53 as well as on their ultrastructure 54. Scanning and transmission electron microscopy have since been used to analyze the ultrastructure of ostrich, guinea fowl, turkey, and Japanese quail sperm cells 555657. However, this usually requires the use of phosphate-buffered glutaraldehyde solutions to fix the sample, followed by dehydration in ascending concentrations of ethanol,57 and this can strongly affect sperm morphometric variables.…”

“…Scanning and transmission electron microscopy have since been used to analyze the ultrastructure of ostrich, guinea fowl, turkey, and Japanese quail sperm cells 555657. However, this usually requires the use of phosphate-buffered glutaraldehyde solutions to fix the sample, followed by dehydration in ascending concentrations of ethanol,57 and this can strongly affect sperm morphometric variables. Indeed, shrinkage often occurs when biological material is prepared for electron microscopy 58.…”

“…Indeed, shrinkage often occurs when biological material is prepared for electron microscopy 58. This may explain why both chicken and turkey sperm morphometric variables are usually recorded as smaller when examined in the electron microscope5354 than in the light microscope 557…”

“…Most studies have involved conventional techniques and the subjective assessment of sperm variables;6061 unfortunately, these methods can return significantly different results when performed in different laboratories or by different operators 626364. Eosin-nigrosin staining has been used to measure sperm traits in duck spermatozoa,65 and amido black, Spermac®57 and other stains5566 in the morphometric analysis of quail and rooster sperm, but they provide conflicting results.…”

“…Sperm morphometric data have been reported for only a few bird species, with most recorded for roosters, turkeys, and quails 535793. Only, recently, some studies have focused on wild species.…”