The process whose specific outcome is the progression of a spermatid over time, from its formation to the mature structure.

Any process involved in the controlled movement of a flagellated sperm cell.

Any process that results in a change in state or activity of a cell (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a reactive oxygen species stimulus. Reactive oxygen species include singlet oxygen, superoxide, and oxygen free radicals.

The assembly of a cilium, a specialized eukaryotic organelle that consists of a filiform extrusion of the cell surface. Each cilium is bounded by an extrusion of the cytoplasmic membrane, and contains a regular longitudinal array of microtubules, anchored basally in a centriole.

The assembly of a cilium, a specialized eukaryotic organelle that consists of a filiform extrusion of the cell surface. Each cilium is bounded by an extrusion of the cytoplasmic membrane, and contains a regular longitudinal array of microtubules, anchored basally in a centriole.

A cytoskeletal structure surrounding the axoneme and outer dense fibers of the sperm flagellum. Consists of two longitudinal columns connected by closely arrayed semicircular ribs that assemble from distal to proximal throughout spermiogenesis. The fibrous sheath probably influences the degree of flexibility, plane of flagellar motion, and the shape of the flagellar beat.

A cytoskeletal structure surrounding the axoneme and outer dense fibers of the sperm flagellum. Consists of two longitudinal columns connected by closely arrayed semicircular ribs that assemble from distal to proximal throughout spermiogenesis. The fibrous sheath probably influences the degree of flexibility, plane of flagellar motion, and the shape of the flagellar beat.

Outer arm structure present on the outer doublet microtubules of ciliary and flagellar axonemes. Outer dynein arms contain 2-3 heavy chains, two or more intermediate chains and a cluster of 4-8 light chains. Inner and outer dynein arms have different functions in the generation of microtubule-based motility.

Outer arm structure present on the outer doublet microtubules of ciliary and flagellar axonemes. Outer dynein arms contain 2-3 heavy chains, two or more intermediate chains and a cluster of 4-8 light chains. Inner and outer dynein arms have different functions in the generation of microtubule-based motility.

The segment of the sperm flagellum where the mitochondrial sheath ends, and the outer dense fibers (ODFs) associated with outer axonemal doublets 3 and 8 are replaced by the 2 longitudinal columns of the fibrous sheath (FS) which run the length of the principal piece and are stabilized by circumferential ribs. The principal piece makes up ~2/3 of the length of the sperm flagellum and is defined by the presence of the FS and of only 7 (rather than 9) ODFs which taper and then terminate near the distal end of the principal piece.

A small amount of cytoplasm surrounded by a cell membrane that is generally retained in spermatozoa after spermiogenesis, when the majority of the cytoplasm is phagocytosed by Sertoli cells to produce \residual bodies\. Initially, the droplet is located at the neck just behind the head of an elongated spermatid. During epididymal transit, the cytoplasmic droplet migrates caudally to the annulus at the end of the midpiece; the exact position and time varies by species. The cytoplasmic droplet consists of lipids, lipoproteins, RNAs, a variety of hydrolytic enzymes, receptors, ion channels, and Golgi-derived vesicles. The droplet may be involved in regulatory volume loss (RVD) at ejaculation, and in most species, though not in humans, the cytoplasmic droplet is lost at ejaculation. Note that the cytoplasmic droplet is distinct from \excessive residual cytoplasm\ that sometimes remains in epididymal spermatozoa, particularly when spermiogenesis has been disrupted.