Abstract:Among species of the Chiroptera, spermatogenesis and the fully differentiated spermatozoa differ in morphological and ultrastructural detail. This study therefore aimed to ultrastructurally characterize the spermatogenesis and the spermatozoa of Carollia perspicillata (Phyllostomidae) and compare the process with other species of bats and mammals. The differentiation of spermatogonia is similar to other bats and to Primates, with three main spermatogonia types: Ad, Ap, and B. Meiotic divisions proceed similarl… Show more
“…However, even within mammals, an assortment of sperm shapes, especially relating to the head, can be observed (examples of sperm head shapes across a variety of taxa are given in Fig. 2); from the ovate-like shape of pig and human sperm, to the falciform sperm head of rodents, the ensiform sperm heads seen in some species of bats (Beguelini et al 2014), and the more square-headed sperm of orcas and beluga whales (Miller et al 2002). Fig.…”
Studies of chromosome and genome biology often focus on condensed chromatin in the form of chromosomes and neglect the non-dividing cells. Even when interphase nuclei are considered, they are often then treated as interchangeable round objects. However, different cell types can have very different nuclear shapes, and these shapes have impacts on cellular function; indeed, many pathologies are linked with alterations to nuclear shape. In this review, we describe some of the nuclear morphologies beyond the spherical and ovoid. Many of the leukocytes of the immune system have lobed nuclei, which aid their flexibility and migration; smooth muscle cells have a spindle shaped nucleus, which must deform during muscle contractions; spermatozoa have highly condensed nuclei which adopt varied shapes, potentially associated with swimming efficiency. Nuclei are not passive passengers within the cell. There are clear effects of nuclear shape on the transcriptional activity of the cell. Recent work has shown that regulation of gene expression can be influenced by nuclear morphology, and that cells can drastically remodel their chromatin during differentiation. The link between the nucleoskeleton and the cytoskeleton at the nuclear envelope provides a mechanism for transmission of mechanical forces into the nucleus, directly affecting chromatin compaction and organisation.
“…However, even within mammals, an assortment of sperm shapes, especially relating to the head, can be observed (examples of sperm head shapes across a variety of taxa are given in Fig. 2); from the ovate-like shape of pig and human sperm, to the falciform sperm head of rodents, the ensiform sperm heads seen in some species of bats (Beguelini et al 2014), and the more square-headed sperm of orcas and beluga whales (Miller et al 2002). Fig.…”
Studies of chromosome and genome biology often focus on condensed chromatin in the form of chromosomes and neglect the non-dividing cells. Even when interphase nuclei are considered, they are often then treated as interchangeable round objects. However, different cell types can have very different nuclear shapes, and these shapes have impacts on cellular function; indeed, many pathologies are linked with alterations to nuclear shape. In this review, we describe some of the nuclear morphologies beyond the spherical and ovoid. Many of the leukocytes of the immune system have lobed nuclei, which aid their flexibility and migration; smooth muscle cells have a spindle shaped nucleus, which must deform during muscle contractions; spermatozoa have highly condensed nuclei which adopt varied shapes, potentially associated with swimming efficiency. Nuclei are not passive passengers within the cell. There are clear effects of nuclear shape on the transcriptional activity of the cell. Recent work has shown that regulation of gene expression can be influenced by nuclear morphology, and that cells can drastically remodel their chromatin during differentiation. The link between the nucleoskeleton and the cytoskeleton at the nuclear envelope provides a mechanism for transmission of mechanical forces into the nucleus, directly affecting chromatin compaction and organisation.
“…The wide geographic distribution and consequent variation in abiotic factors, such as latitude, temperature, humidity, rainfall, and food availability; directly influence the reproductive characteristics and patterns of bats (Fleming et al, ), and lead to the development of many reproductive specializations. Examples of these features are: testicular regression during hibernation; testicular regression in a tropical habitat, without a period of hibernation; an extended duration of sperm storage in the cauda epididymis in males and in the uterine cornua in females; asynchrony between spermatogenesis and the mating period; delayed ovulation, fertilization, and implantation in the female reproductive tract; major differences in the position and morphology of the testes and epididymis and in the ultrastructural morphology of the spermatozoa; and large seasonal variations in reproductive patterns (Fawcett and Ito, ; Gustafson, ; Krutzsch, ; Breed and Leigh, ; Phillips et al, ; Sang‐Sick et al, ; Crichton and Krutzsch, ; Beguelini et al, , , a, b, c, d, a, b; Christante et al, 2014; Negrin et al, ).…”
This study aimed to morphologically characterize and compare the male reproductive accessory glands (RAGs) of bats belonging to the five Brazilian subfamilies of the family Phyllostomidae (Carollia perspicillata-Carollinae; Desmodus rotundus-Desmodontinae; Glossophaga soricina-Glossophaginae; Phyllostomus discolor-Phyllostominae and Platyrrhinus lineatus-Stenodermatinae). The study demonstrated that the RAGs of phyllostomid bats were comprised of a pair of extra-abdominal bulbourethral glands and an intra-abdominal complex, composed of paraurethral glands and a prostate with two (Desmodontinae and Stenodermatinae) or three (Carollinae, Glossophaginae and Phyllostominae) different regions, with the absence of the seminal vesicles; this pattern possibly evolved from a process of compaction of the prostatic regions from an ancestor with three regions.
“…These characteristics have been recently confirmed by genome-wide analyses. Therefore, sperm ultrastructural traits are species specific and uniquely adapted for successful reproduction (Cetica et al 1997;Beguelini et al 2014).…”
Section: Introductionmentioning
confidence: 99%
“…Sperm head forms are species characteristic and vary from bullet shaped to globular shaped along with the number of mitochondria in the tail region. Therefore, the sperm morphological traits, such as shape and length of the head, mid-piece, and flagellum, are believed to be associated with evolution as an independent unit (Immler et al 2012;Beguelini et al 2014).…”
The structural and morphometric traits of spermatozoa reflect species-specific evolutionary and functional characters. The shrew, Crocidura shantungensis, which is an indigenous species of Ulleung-do, is dominant on this island and is suspected to have unique traits different from other shrews. Based on a previous sperm ultrastructural analysis, the structural and morphometric traits of caudal epididymal spermatozoa were evaluated by light, scanning, and transmission electron microscopy. Total length was 110.0 lm. The head was paddle shaped with a globular nucleus and was 16.0 lm in length. The acrosomal cap covered four-fifths of the nucleus, and the subacrosomal space had sawtooth-shaped edges. The number of mitochondrial gyres was 84-86. Nine segmented columns in the neck consisted of 12 knobs, and each column was fused with outer dense fiber. The outer dense fibers 1, 5, and 6 were thicker than the others. Outer fiber 1 was shaped like a horseshoe, whereas 5 and 6 were fused with each other. Numerous satellite fibers were scattered on the mid-piece between outer fibers 4 and 5, and 6 and 7. Two specific strong electron-dense fibers were found uniquely near the satellite fibers. In conclusion, our results demonstrate that the caudal sperm of Ulleung-do C. shantungensis has unique ultrastructural and morphometric traits based on common sperm characters of the subfamilies, suggesting unique physiological roles in reproduction.
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