The cycle of the seminiferous epithelium in Bali cattle (Bos sondaicus)

The duration of the cycle of the seminiferous epithelium in 5 mature Bali bulls was 11.75 days (standard error of estimate 0.52 days). The relative frequencies of the stages of the cycle of the seminiferous epithelium (morphological classification) of Bali cattle differed from other cattle and buffalo in that there were lower frequencies of Stage 1 and 2 tubules, and higher frequencies of Stage 3, 6 and 7 tubules.     

The length of the cycle of seminiferous epithelium in goats (Capra hircus).

This is the first report in literature showing the length of the seminiferous epithelium cycle in goats. In the present study, the duration of spermatogenesis was estimated using intratesticular injections of tritiated thymidine. Animals were castrated at 4 h, 7 days, and 11 days after injections. The duration of each spermatogenic cycle in goats is 10.6 +/- 0.5 days (SEM). Considering that the total duration of spermatogenesis takes about 4.5 cycles of seminiferous epithelium, spermatogenesis was estimated to last 47.7 days. The approximate primary spermatocytes life span is 14.1 days, while spermiogenesis in goats lasts 14.9 days. Staging in goats was based on the tubular morphology, where 8 stages of the cycle are yielded for all species. The relative stage frequencies in goats, based on 400 seminiferous tubule cross sections for each animal were as follows: stage 1: 15.8 +/- 1.0%; stage 2: 12.8 +/- 0.5%; stage 3: 20.5 +/- 0.9%; stage 4: 10.7 +/- 0.7%; stage 5: 11.6 +/- 0.6%; stage 6: 9.3 +/- 1.1%; stage 7: 7.6 +/- 0.4%; stage 8: 11.7 +/- 0.6%. The pre-meiotic, meiotic and post-meiotic phases' relative frequencies were 49.1%, 10.7% and 40.2%, respectively. The duration of spermatogenesis in goats is very similar to that found in rams.     

Seminiferous epithelium cycle and its duration in capybaras (Hydrochoerus hydrochaeris).

Although capybara is the largest rodent in the world and largely distributed in Central and South America, there is no report in the literature concerning the cycle of seminiferous epithelium in this species. In the present study, the length of spermatogenic cycle was estimated using intratesticular injections of tritiated thymidine. Animals were sacrificed at 1 h, 8 days, and 17 days after injections. The duration of one spermatogenic cycle in capybaras is 11.9 +/- 0.1 days (SEM). Spermatogenesis was estimated to last 53.6 days, when considering that the total duration of spermatogenesis takes about 4.5 cycles of seminiferous epithelium. The approximate life span of primary spermatocytes is 19.1 days, while spermiogenesis lasts 16.7 days. Staging in capybaras was based on the spermatid nuclei shape and location of spermatids, named tubular morphology method, which consists of 8 stages in all species. The relative stage frequencies in capybaras, based on the analysis of approximately 200 cross sections of seminiferous tubule for each of the ten animals were as follow: stage 1: 14.0 +/- 1.5%; stage 2: 15.1 +/- 1.0%; stage 3: 15.7 +/- 1.1%; stage 4: 14.6 +/- 1.1%; stage 5: 8.7 +/- 0.7%; stage 6: 7.0 +/- 0.7%; stage 7: 9.4 +/- 0.9%; stage 8: 15.5 +/- 1.0%. The pre-meiotic, meiotic and post-meiotic phases relative frequencies were 44.8%, 14.6% and 40.6%, respectively. Compared to most rodents investigated so far, the duration of spermatogenesis in capybaras is relatively long.     

Cycle of the seminiferous epithelium and its duration in the zebu, Bos indicus

The cycle of the seminiferous epithelium was studied in Nelore zebu bulls 4–6 years old. The stages of the cycle were determined according to the shape and position of spermatid nuclei and the presence of meiotic divisions in cross-sections of seminiferous tubules. The relative frequencies of stages 1 to 8 were, respectively: 31.3 ± 0.5, 12.2 ± 0.7, 21.2 ± 0.5, 8.8 ± 0.6, 4.2 ± 0.4, 5.7 ± 0.6, 6.3 ± 0.5 and 10.3 ± 0.5. The duration of the cycle was estimated by autoradiography using tritiated thymidine injected directly into the testes. The mean duration of one cycle was estimated to be 14.0 ± 0.4 days.     

The Cycle of the Seminiferous Epithelium of the Turkish Hamster (Mesocricetus brandti)

The Turkish hamster ( Mesocricetus brandti ) has become a desirable species for experimentation in testicular function, photoperiod, reproductive hormones and hibernation. Basic data on the kinetics of the seminiferous epithelium have not yet been published. In the present study, the cycle of the seminiferous epithelium was divided into eight stages based on the overall cellular associations of 1540 cross sections of tubules. The mean relative frequencies for stages 1 through 8 were 5.9, 3.3, 11.7, 6.7, 7.2, 28.5, 21.6 and 15.1%, respectively. The absolute duration of the cycle of the seminiferous epithelium was determined by administration of ³H-thymidine, removal of testes at intevals after injection and autoradiography. The mean duration of one cycle was estimated at 8.0 days and the duration of stages 1 through 8 was 0.5, 0.3, 0.9, 0.5, 0.6, 2.3, 1.7 and 1.2 days, respectively. The duration of meiotic prophase was 11.5 days and of spermiogenesis was 13.8 days. The life span of preleptotene cell was estimated at 1.21 days, leptotene, 0.73 days, zygotene, 0.94 days and pachytene, 7.37 days. The total cycle length of spermatogenesis as usually calculated was 32.0 days.     

Frequency of the stages in the cycle of the seminiferous epithelium in the rat

This study determined the optimum number of tubules to be counted per testis cross section, and the number of animals per treatment group, when changes in stage frequencies in the cycle of the seminiferous epithelium are criteria for assessing effects of treatment on spermatogenesis. A data base of 9,672 observed and staged tubules was collected from testicular cross sections of 15 Sprague-Dawley rats. A significant variation between animals was found for the frequencies of Stages I, II, IV, VI, VIII, and XIII. Computer simulation was used to randomly select different combinations of animal and tubule numbers from the observed data. Stage frequency means from each simulation experiment were compared statistically to observed mean frequencies. A model that used data from all 14 stages was analyzed. The following conclusions were made: a) a minimum of 200 tubule cross sections/testis is recommended for estimating stage frequencies; b) for a fixed number of tubules scored, the number of animals sampled is more important than the number of tubules per animal in reducing variance; c) to detect a difference of 2 standard deviations from the mean with a 2% error rate and examining 200 tubules/testis, at least 12 animals must be used per group when assessing all 14 stages; d) when individual stages are examined using 10 animals per group, only Stage VII has 80% or greater power of test (alpha = 0.05) to detect a frequency difference; e) pooling stages into 3-4 groups is recommended to improve the power of detecting a treatment difference.     

Spatial arrangement of the stages of the cycle of the seminiferous epithelium in the Japanese quail, Coturnix coturnix japonica

The spatial arrangement of the stages of the cycle of the seminiferous epithelium of the Japanese quail was investigated by preparing three-dimensional reconstructions of a seminiferous tubule from each of 3 quails. It was found that the stages were not distributed at random, but were arranged in a wave which spiralled helically along a seminiferous tubule. Adjacent stages in space were always adjacent numbers in the cycle of the seminiferous epithelium. Complete spermatogenetic waves were found in which all 10 stages of the cycle were in sequential order. However, in most waves the sequential order of stages was disturbed by the occurrence of modulations. The area of a cellular association varied from 4600 to 41,600 microns 2 with a mean +/- s.e.m. (3 animals) of 17,902 +/- 2614 microns 2. The number of Sertoli cells involved in an association ranged from 4 to 35, with a mean +/- s.e.m. (3 animals) of 13.5 +/- 2.8. The findings support our earlier suggestion that the kinetics of spermatogenesis in the quail are fundamentally similar to the pattern which has been described for mammals.     

Cytological organization of the seminiferous epithelium in the Australian rodents Pseudomys australis and Notomys alexis

Absolute and relative testis mass of two species of conilurine rodents, the plains rat (Pseudomys australis) and the hopping mouse (Notomys alexis), were markedly different. In plains rats the testis comprised approximately 3% of body mass while in hopping mice they rarely accounted for more than 0.2%. In both species, 8 cellular associations, or cycle stages, were recognized in the seminiferous epithelium. The relative frequencies, and hence durations, of Stages I to VIII were 5.1, 7.0, 12.5, 10.5, 5.4, 25.9, 4.4 and 29.0% of one cycle for plains rats (N = 14), and 20.4, 10.9, 9.6, 8.1, 5.1, 20.4, 14.7 and 10.8% for laboratory-bred hopping mice (N = 35). Generally, the relative durations of the cycle stages were very similar between plains rat individuals, but were variable between hopping mice. Also, organization of the seminiferous epithelium was less rigid in hopping mouse testes, and several anomalies were observed. These included: the occurrence of 2-4 cellular associations in about 20% (range 11.3-33.9%) of tubular cross-sections, deviations in cellular composition in certain cycle stages from that usually observed, and an increased incidence of degenerating cells, together with the presence of multinucleated "giant' cells, within the seminiferous epithelium.     

The cycle of the seminiferous epithelium in Landrace boars

The present study describes the morphological features of the eight stages of the seminiferous epithelium in Landrace boars according to the tubular morphology method, as well as their relative frequency, length, and duration. In Landrace boars the pre-meiotic stages occupied the 31.9 +/- 19.9% of the spermatogenic cycle and had a total length of 1788.8 +/- 1153.0 microm and a duration of 2.78 days; they were mainly characterised by the presence of leptotene and pachytene spermatocytes and round spermatids. Meiotic stages, with a relative frequency of 16.4 +/- 6.8%, a length of 787.1 +/- 603.1 microm and a duration of 1.41 days, contained spermatocytes in advanced meiosis I and/or in meiosis II and elongating spermatids grouped in bundles. Post-meiotic stages occupied the 50.6 +/- 20.4% of the spermatogenic cycle and had a length of 2096.8 +/- 1175.0 microm and a duration of 4.37 days; the most important event of these stages was the spermiation, which included the complete remodelling of sperm head and tail and the releasing of spermatozoa into the lumen, as well as the formation of residual bodies. From data obtained we concluded that both germ cell associations of the stages maintain constant among Landrace boars, and that the relative frequency, length and duration of the stages were directly dependent of the cytological transformations on the seminiferous tubules.     

Proceedings: The role of the Sertoli cell in phagocytosis of the residual bodies of spermatids

The fate of residual bodies which form as spermatids are released from the seminiferous epithelium has been studied as part of a cytological investigation of the Sertoli cells during the stages of rat spermatogenesis. Testes from normal adult rats were fixed by whole body perfusion. All 14 stages of rat spermatogenesis were identified and studied by light and electron microscopy. Residual bodies are released at Stage 8 and are found in the luminal spaces of the seminiferous epithelium. During Stage 9 they appear to migrate peripherally in channels of the Seroli cell cytoplasm. During this migration, lysosomal-like bodies surround the residual bodies and appear to be involved in the degradative process. A considerable proportion of the lipid material persists and forms basal collections in the Sertoli cells. The lipid inclusions reach a peak at Stages 13 and 14 of the cycle and persist until Stage 2 and 3. Some lipid inclusions persist until Stage 4 to 7 when noticeable decrease occurs corresponding to the peripheral migration of maturing spermatids.     

Reproduction in the male llama (Lama glama), a South American camelid. I. Spermatogenesis and organization of the intertubular space of the mature testis

The cycle of the seminiferous epithelium of the llama was divided into eight stages, using as criteria the shape and distribution of the germ cell nuclei, the location of the spermatids, the presence of meiotic figures and the release of spermatozoa from the tubular wall. Cell populations making up each stage are described. The relative frequencies of stages 1 through 8 were: 9.86, 12.46, 17.65, 14.12, 5.81, 8.09, 13.04 and 18.89%, respectively. In the seminiferous epithelium, spermatogonia of the A and B type are present and twelve spermiogenic steps can be recognized. Interstitial (Leydig) cells are packaged together forming large masses and elongated cords and share the intertubular space with one or two central great lymphatic vessels and few capillaries. Season male Leydig cells contain lipid droplets in their cytoplasm and show a marked immunoreactive testosterone reaction.     

Identification of stage-specific proteins synthesized by rat seminiferous tubules

Experiments were conducted to determine how the cycle of the seminiferous epithelium influenced synthesis and secretion of proteins by seminiferous tubules. Tubular segments were treated with collagenase and then cultured with [35S]methionine. These myoid cell-depleted tubules isolated from different stages of the epithelial cycle exhibited, at Stages VI and XII, two distinct peaks of secretion of total radiolabeled proteins. Two-dimensional gel electrophoresis indicated that the patterns of secreted proteins from these two stages were remarkably different, while those from other stages were intermediate between those at the peaks. At least 15 proteins were secreted cyclically, many of them previously unrecognized products of the seminiferous epithelium. One product, designated Cyclic Protein-2 (CP-2), exhibited a pronounced cycle of secretion, its peak at Stage VI being 30-fold greater than at its nadir at Stages XII-XIV. Further investigation indicated that CP-2 did not appear to originate from myoid cells or dispersed germ cells but could be recovered from Sertoli cell-enriched cultures prepared from Stage VI tubules. Protein secretion by tubular segments was also characterized by immunoprecipitation with two polyspecific antisera directed against Sertoli cell products. Five secretory proteins were identified which had cycles different from one another and from CP-2. In contrast to secreted products, the synthesis of most cellular proteins by tubular segments remained relatively constant throughout the cycle. It is concluded: 1) segments of the seminiferous epithelium secrete proteins into the culture medium which are distinct from cellular proteins; 2) the synthesis of many of these proteins varies with the epithelial cycle; and 3) several of the secreted proteins are of Sertoli cell origin, including a newly identified protein, CP-2. This indicates that the morphology and the protein synthetic capacity of the seminiferous epithelium are coordinated over space and time.     

Stages and duration of the cycle of the seminiferous epithelium in oncilla (Leopardus tigrinus, Schreber, 1775)

Six adult Leopardus tigrinus (oncilla) were studied to characterize stages of the seminiferous epithelium cycle and its relative frequency and duration, as well as morphometric parameters of the testes. Testicular fragments were obtained (incisional biopsy), embedded (glycol methacrylate), and histologic sections examined with light microscopy. The cycle of the seminiferous epithelium was categorized into eight stages (based on the tubular morphology method). The duration of one seminiferous epithelium cycle was 9.19 d, and approximately 41.37 d were required for development of sperm from spermatogonia. On average, diameter of the seminiferous tubules was 228.29 μm, epithelium height was 78.86 μm, and there were 16.99 m of testicular tubules per gram of testis. Body weight averaged 2.589 kg, of which 0.06 and 0.04% were attributed to the testis and seminiferous tubules, respectively. In conclusion, there were eight distinct stages in the seminiferous epithelium, the length of the seminiferous epithelium cycle was close to that in domestic cats and cougars, and testicular and somatic indexes were similar to those of other carnivores of similar size.     

Relative volume of Sertoli cells in monkey seminiferous epithelium: a stereological analysis.

Techniques of quantitative stereology have been utilized to determine the relative volume occupied by the Sertoli cells and germ cells in two particular stages (I and VII) of the cycle of the seminiferous epithelium. Sertoli cell volume ranged from 24% in stage I of the cycle to 32% in stage VII. Early germ cells occupied 3.4% in stage I (spermatogonia) and 8.7% in stage VII (spermatogonia and preleptotene spermatocytes). Pachytene spermatocytes occupied 15% (Stage I) and 24% (stage VII) of the total volume of the seminiferous epithelium. In stage I the two generations of spermatids comprised 58% of the total epithelium by volume, whereas in stage VII, after spermiation, the acrosome phase spermatids occupied 35% of the total seminiferous epithelial volume.     

The cycle of the seminiferous epithelium in the Japanese quail (Coturnix coturnix japonica) and estimation of its duration

A regular, well defined spermatogenic cycle was found in the Japanese quail by examining thin sections of isolated lengths of seminiferous tubules embedded in epoxy resin to resolve the structure of developing spermatids. The stages of the cycle initially were identified in studies using a preparatory method for fixation which separated adjacent cellular associations. The cycle was divided into 10 stages with relative frequencies (%) of Stages I to X respectively of: 11.9, 14.8, 24.1, 10.3, 8.2, 6.4, 9.4, 5.5, 3.8 and 5.4. The duration of one cycle was 2.69 +/- 0.08 days (mean +/- s.e.m.) as determined by intraventricular injection of [3H]thymidine and autoradiographic examination of the testes 1-4 days later. It was estimated that lifespans were 2.01 days for type B spermatogonia, 3.86 days for primary spermatocytes, 0.15 days for secondary spermatocytes, and 4.54 days for spermatids. The results suggest that the kinetics of spermatogenesis in the quail are fundamentally similar to the pattern in mammals.     

Chromosome banding homologies in Swamp and Murrah buffalo

Silver staining of Swamp buffalo (2n = 48) metaphase chromosomes revealed telomeric nucleolus organizer regions (NOR's) located on five pairs of autosomes identified by R-banding as numbers 4 p (submetacentric), 8, 20, 22, and 23 (acrocentrics); interphase nuclei also showed no more than five nucleoli. The Murrah buffalo (2n = 50) was previously reported to have telomeric NOR's located on six pairs, -3 p and 4 p (submetacentric), 8, 21, 23, and 24 (acrocentrics). By comparing the two types of buffalo it was concluded that: all of the chromosomes are similar in banding patterns; chromosome 1 of Swamp results from a telomere-centromere tandem fusion between two chromosomes identified as 4 p and 9, respectively, in the Murrah karyotype, thus accounting for the reduced diploid number of Swamp buffalo; the fusion causes the loss of NOR's on the telomeres of chromosome 4, thus accounting for the reduced number of NOR chromosome pairs of Swamp; the presence of a pale C-band are in the region of junction between chromosome 4 and 9 involved in the fusion suggests that the centromeric region of the later is retained and altered.     

Testosterone micromilieu in staged rat seminiferous tubules

Endogenous testosterone concentrations in rat seminiferous tubules were measured in relation to different stages of the cycle of the seminiferous epithelium. For this purpose, the seminiferous tubules were mechanically separated from the interstitial tissue on a cooled (1 degree C) petri dish under a stereomicroscope without added medium. After recognition of the stages of the cycle by transillumination, the specimens were rapidly transferred by dry forceps into test tubes for testosterone radioimmunoassay. The results of the dry dissection method were compared with measurements on tubules that were kept after separation in phosphate buffered saline (PBS, pH 7.4), in order to reveal the possible leakage of testosterone from the tubules. The maximal concentration of testosterone per unit length of seminiferous tubule was found in stages VII and VIII of the cycle (288 +/- 60 fmol/cm, mean +/- SEM, n = 12), and the minimal in stages IX-XII (219 +/- 57 fmol/cm, P less than 0.01). If the levels were correlated with unit volumes of the seminiferous tubules, identical concentrations of testosterone (521-542 fmol/mm3, approx. 500 nmol/l) were found in the different stages of the cycle. Despite the similarity of testosterone concentrations in the different parts of the seminiferous tubules the local concentrations of biologically active (i.e. free) testosterone may be modulated by extracellular and intracellular androgen binding components.     

Reproductive function in the Australian Swamp buffalo bull: Age effects and seasonal effects

Swamp buffalo exhibited seasonal variations in daily sperm production and in daily sperm production per gram of testis parenchyma. Maximum rates occurred in the late wet season and early dry season. There was no spermatogenesis detected in 1-yr-old bulls. Daily sperm production per gram of testis parenchyma increased thereafter up to 3.5 yr of age, and was similar in all older age groups. Scrotal circumference in bulls of this age ranged from 20 to 21 cm. Scrotal circumference and daily sperm production increased rapidly up to maturity, and increased less rapidly thereafter. Mean+/-SEM daily sperm production per gram in 146 mature buffalo bulls was 14.04 x 10(6)+/-0.39 x 10(6) and mean+/-SEM daily sperm production was 1.86 x 10(9)+/- 0.07 x 10(9). Mean+/-SEM epididymal sperm reserves in adult bulls numbered 9.7 x 10(9) +/- 0.07 x 10(9). These were distributed between the caput, corpus and cauda epididymis in the proportions of 28.82, 14.63 and 60.55, respectively. Mean+/-SEM epididymal transit time was 5.65+/-0.24 d.     

Duration of spermatogenesis and daily sperm production in the jaguar (Panthera onca)

The jaguar, like most wild felids, is an endangered species. Since there are few data regarding reproductive biology for this species, our main goal was to investigate basic aspects of the testis and spermatogenesis. Four adult male jaguars were utilized; to determine the duration of spermatogenesis, two animals received an intratesticular injection of H(3)-thymidine. Mean (+/-SEM) testis weight and the gonadosomatic index were 17.7+/-2.2g and 0.05+/-0.01%, respectively, whereas the seminiferous tubules and the Leydig cells volume density were 74.7+/-3.8 and 16.7+/-1.6%. Eight stages of spermatogenesis were characterized, according to the tubular morphology system and acrosome development. Each spermatogenic cycle and the entire spermatogenic process (based on 4.5 cycles) lasted approximately 12.8+/-0.01 and 57.7+/-0.07 d. The number of Sertoli and Leydig cells per gram of testis was 29+/-4x10(6) and 107+/-12x10(6). Based on the number of round spermatids per pachytene spermatocyte (2.8+/-0.3:1; meiotic index); significant cell loss (30%) occurred during the two meiotic divisions. There were approximately eight spermatids for each Sertoli cell (Sertoli cell efficiency), whereas the daily sperm production per gram of testis was 16.9+/-1.2x10(6). We expect that in the near future, the knowledge obtained in the present investigation will facilitate, utilizing germ cell transplantation, preservation of the germinal epithelium and the ability to generate sperm from jaguars in testes of domestic cats.