Effect of collection frequency on quantitative and qualitative characteristics of pigeon ( Columba livia ) semen

Soley

2011

Theriogenology

Little detailed information is currently available on the incidence and morphological characteristics of abnormal sperm in the emu (Dromaius novaehollandiae) and of ratites in general. This situation is further compounded by the lack of a uniform system for the morphological classification of avian sperm defects. Considering the important role that sperm morphology plays in the assessment of semen quality, a detailed description of avian sperm defects is of paramount importance. Based on morphological data provided by light and electron microscopy, a mean of 17.3% abnormal sperm was recorded in semen samples collected from the distal deferent duct of four adult emus during the middle of the breeding season. Four categories of defects were identified. Head defects (57.2% of total defects) consisted of bent heads, macrocephalic heads, round heads and acephalic sperm. Zones of incomplete chromatin condensation and retained cytoplasmic droplets appeared to be implicated in head bending, while giant heads were often associated with multiple tails. Acephalic sperm revealed a complete tail devoid of a head which was replaced by a small spherical structure. Tail defects (22.6% of total defects) were subdivided into neck/midpiece defects and principal piece defects. In the neck/midpiece region disjointed sperm were the exclusive defect noted and were characterized by the complete separation of the head and midpiece in the neck region but within the confines of the plasmalemma. Defects observed in the principal piece were subdivided into short tails, coiled tails and multiple tails. No conclusive evidence was obtained that tail coiling represented the 'Dag' defect. Biflagellate sperm were the most common form of multiple tails, demonstrating two complete tails with all the normal structural elements. Cytoplasmic droplets (13.9% of total defects) were classified as a separate defect. The location and eccentric positioning of retained cytoplasmic droplets was similar to that described in ostrich sperm although the composition of the droplets differed markedly between the two species. A small percentage of sperm (6.3% of total sperm defects) displayed multiple abnormalities. Based on these findings we propose a morphological classification for abnormal ratite sperm identifying head and tail defects, with additional categories for cytoplasmic droplets and multiple defects. Each category is further subdivided to reflect a range of specific defects within the category. It is envisaged that additional defects will be added to each category or that new categories may be added as future studies on the detailed morphology of avian sperm defects are completed.

Section: Cytoplasmic Dropletsmentioning

confidence: 99%

Incidence, structure and morphological classification of abnormal sperm in the emu (Dromaius novaehollandiae)

Soley

2011

Theriogenology

“…In the Houbara bustard macrocephalic sperm are 14 reported to occasionally be associated with multiple tails [40]. Although macrocephalic sperm have been reported in other avian species [6,32,[47][48][49], no mention is made of multiple tails or other defects associated with this anomaly. A more careful assessment of avian sperm defects may clarify this situation.…”

Section: Discussionmentioning

confidence: 99%

Structural peculiarities associated with multiflagellate sperm in the emu, Dromaius novaehollandiae

Soley

2012

Theriogenology

Multiflagellate sperm represent a rare defect in mammals and also in the emu where an incidence of only 1% multiflagellate sperm was recorded in semen samples from 15 birds. Biflagellate sperm were the most frequent form of the defect observed, but 3-to 5-tailed sperm were also noted. An association was apparent between multiple tails and macrocephalic sperm which accounted for 0.6% of multiflagellate sperm. Structural features of the defect were generally similar to those seen in mammals. The duplicated tails shared a single midpiece which housed supernumerary centriolar complexes, each surrounded by a mitochondrial sheath. A single row of mitochondria separated adjacent centriolar complexes. Elements of the connecting piece (segmented columns, capitellum) appeared normal. The nuclear base appeared flat, staggered or scalloped depending on the number 2 and depth of additional implantation fossae. Multiflagellate emu sperm of normal head dimensions displayed a widened nuclear base (in the form of an attenuated peripheral nuclear extension) to accommodate the attachment of the additional centriolar complexes. Defective mammalian sperm do not show this modification of the nuclear base as the inherently wider sperm head is able to accommodate the supernumerary centrioles. Although often spiraled around each other, the duplicated principal pieces of the tail were generally separated and free. However, in some cells the proximal parts were collectively bound within the plasmalemma. Multiflagellate sperm appear to have a dual origin with some defective cells originating from incomplete cytokinesis and others as a result of abnormal centriolar duplication.

“…Ferdinand (1992) described a wide range of acrosome defects in the goose and Klimowicz et al (2005), without providing any detail, mentioned the presence of acrosome defects in the pigeon. Maeda et al (1986) reported swollen acrosomes in chickens, although this only occurred after the cells had been treated with cryo-protectants.…”

Section: Head Defectsmentioning

confidence: 99%

“…Midpiece abnormalities appear to be a common defect of avian species, particularly defects described as "bent midpiece" and "deformed midpiece" (Chelmońska et al, 2008;Klimowicz et al,. 2005;Maeda et al, 1984;Nwakalor et al, 1988;Penfold et al, 2000;Siudzińska and Łukaszewicz, 2008;Umapathy et al, 2005).…”

Section: Tail Defectsmentioning

confidence: 99%

“…Although macrocephalic heads also formed a large proportion of total head defects in the emu (18.3%), bent heads, acephalic sperm and round heads collectively contributed to the greater proportion of head defects prevalent in the emu compared to the ostrich. Macrocephalic sperm are commonly found in small numbers in other avian species, such as the guinea fowl (Nwakalor et al, 1988), turkey (Lindsay et al, 1999), pigeon (Klimowicz et al, 2005) and quail (Chelmońska et al, 2008). High numbers of macrocephalic sperm (5-40%) have been reported in the Houbara bustard without any apparent influence on fertility (Lindsay et al, 1999).…”

Section: Head Defectsmentioning

confidence: 99%

See 1 more Smart Citation

A morphological classification of sperm defects in the ostrich (Struthio camelus)

Animal Reproduction Science

Malecki

Bonato

et al. 2014

Commercial ostrich farming is constrained by the absence of a formal animal recording and evaluation scheme as well as by current farming practices. Artificial insemination may have an important role in overcoming these limitations, but requires a thorough knowledge of sperm morphology. Although the morphological characteristics of normal ostrich sperm have been documented, little information is available on the incidence and structural peculiarities of defective sperm in this species. Semen smears were prepared from the ejaculates of five ostriches (Struthio camelus), stained and evaluated. Defects were observed in 17% of sperm studied. Tail defects constituted the most common anomaly.Various forms of bending were the main tail defect, ranging from gentle to acute bends of the principal piece, Dag-like coiling at the head base, sharp reflexes of the midpiece as well as coiling of the endpiece. In contrast, head defects were comparatively low in frequency, with macrocephalic sperm being the defect most frequently observed in this region. Bent, microcephalic, acephalic and round sperm heads were also noted but were few in number. Cytoplasmic droplets occurred frequently in the fixed smears, either associated with the sperm or as free-lying droplets. A small percentage of sperm with multiple defects was recorded. The incidence of morphologically normal sperm in ostrich semen compared favorably with that reported in emu semen, another commercially farmed ratite. However, the range of defects differed appreciably between the two species. Sperm tail anomalies were the most frequent category in the ostrich, whereas head defects comprised the main grouping in the emu.