Further quantification of human spermatogenesis: germ cell loss during postprophase of meiosis and its relationship to daily sperm production

Potential daily sperm production per gram of testicular parenchyma (PDSP/g) based on pachytene plus diplotene primary spermatocytes was determined by two methods for 10 men aged 26 to 53 years and compared with published daily sperm production per gram parenchyma (DSP/g) based on round spermatid nuclei for these same men. The PDSP/g based on primary spermatocytes was similar (P greater than 0.05) whether determined by histometric analysis (10.0 +/- 1.1 X 10(6] or from homogenates of parenchyma (10.4 +/- 1.0 X 10(6]. When PDSP/g values were compared to DSP/g (5.9 +/- 0.9 X 10(6) for the histometric or 5.5 +/- 0.8 X 10(6) for the homogenate method), 44.9 +/- 6.7% loss of potential sperm production during postprophase of meiosis was detected by the histometric approach and 48.3 +/- 7.9% loss by the homogenate method. Similar results were obtained when testes of 15 additional men aged 26 to 53 years were evaluated by the homogenate method; PDSP/g was 10.6 +/- 0.6 X 10(6), DSP/g was 5.8 +/- 0.5 X 10(6), and the loss during postprophase of meiosis was 45.3 +/- 4.4%. For all 25 men, DSP/g was significantly (P less than 0.01) correlated with PDSP/g (r = + 0.70) and with the percentage loss of potential sperm production during postprophase of meiosis (r = 0.86). Over 73% of the variation in DSP/g could be attributed to variation in the percentage loss during postprophase of meiosis. Whether faulty meiotic divisions and/or degenerating secondary spermatocytes were responsible, almost half of the potential sperm production in these 25 men was lost during postprophase of meiosis.     

Quantification of the human Sertoli cell population: its distribution, relation to germ cell numbers, and age-related decline

The human Sertoli cell population was characterized in 14 men by histometric analysis and by direct counts of nuclei in testicular homogenates. Testes obtained at autopsy were perfused with glutaraldehyde and embedded in Epon. Nucleolar and nuclear volumes were determined by the formula of a sphere given the diameter of the nucleoli or average diameter of nuclei measured at the height and width. Nuclear volume was also estimated by adding volumes of nuclear profiles in 0.5-micron serial sections. Sertoli cell number/g was calculated by the product of the percentage nucleoli or nuclei in the parenchyma, parenchymal volume, and histologic correction factor divided by the volume of a single nucleolus or nucleus. Also, Sertoli cell nuclei were counted directly in homogenates of fixed parenchyma. Number of Sertoli cells/g was similar (P greater than 0.05) whether determined by serial sections or in homogenates, but the estimate based on the nucleolar method was higher (P less than 0.01) and the nuclear measurement method was lower (P less than 0.01) than that for serial sections. A group of 37 men aged 20 to 48 yr had significantly (P less than 0.01) more Sertoli cells than did 34 men aged 50 to 85 yr. It is concluded that: 1) the homogenate method is valid for quantification of the Sertoli cell population, 2) Sertoli cells are evenly distributed in different regions of the testis, 3) the average human Sertoli cell supports relatively few germ cells, 4) the human Sertoli cell population declines with age, and 5) there is a significant relationship between sperm production rates and number of Sertoli cells.     

Testicular and epididymal function during the peripuberal period in Brahman bulls receiving various amounts of protein degradable in the rumen

Thirty-nine Brahman bulls with an initial age and weight of 301.7 +/- 4.1 d and 202.7 +/- 4.7 kg, respectively, were randomly allocated to 1 of 2 dietary treatment groups within age, weight and sire in order to study the influence of source of protein and stage of peripuberal period on testicular and epididymal function. In the soybean meal treatment the amount of protein undegradable in the rumen averaged 47%, while it was 72% in the fish meal treatment. The supplements were isocaloric and isonitrogenous. Bulls were electroejaculated, and castrations were performed randomly in a predetermined order when the first ejaculate with the first motile sperm cells (Stage 1), 10 to 25 million (Stage 2), and 50 million or more sperm cells (Stage 3 - puberty) was obtained. Testicular and epididymal traits were analyzed for a single testicle and epididymis. Daily sperm production, daily sperm production per gram of testicular parenchyma, testicular weight and testicular parenchyma weight were not affected by treatment. Bulls receiving fish meal had heavier (P < 0.01) epididymis than soybean meal-fed bulls (6.6 +/- 1.0 vs 3.9 +/- 0.6 g) but similar (P > 0.05) epididymal sperm reserves. Daily sperm production (1 testicle) was 115.2 +/- 0.1, 447.4 +/- 0.1, 792.7 +/- 0.1 million sperm cells, and daily sperm production per gram of testicular parenchyma was 1.5 +/- 0.5, 3.2 +/- 0.6 and 6.4 +/- 0.6 million sperm cells for bulls at Stage 1, 2 and 3, respectively. Sire and amount of undegradable intake protein had significant (P < 0.05) affects on the distribution of epididymal sperm reserves, with soybean meal-fed bulls having the higher proportions of epididymal sperm reserves in the cauda epididymis.     

Increased germ cell degeneration and reduced germ cell:Sertoli cell ratio in stallions with low sperm production

To determine the relationship between germ cell degeneration or germ cell:Sertoli cell ratio and daily sperm production, testes were obtained during the months of May to July (breeding season) and November to January (nonbreeding season) from adult (4 to 20-yr-old) stallions with either high (n = 15) or low (n = 15) sperm production. Serum was assayed for concentrations of LH, FSH and testosterone. Testes were assayed for testosterone content and for the number of elongated spermatids, after which parenchymal samples were prepared for histologic assessment. Using morphometric procedures, the types and numbers of spermatogonia, germ cells and Sertoli cells were determined. High sperm producing stallions had greater serum testosterone concentration, total intratesticular testosterone content, testicular parenchymal weight, seminiferous epithelial height, diameter of seminiferous tubules, numbers of A and B spermatogonia per testis, number of Sertoli cells per testis, and number of B spermatogonia, late primary spermatocytes, round spermatids and elongated spermatids per Sertoli cell than low sperm producing stallions (P < 0.05). The number of germ cells (total number of all spermatocytes and spermatids in Stage VIII tubules) accommodated by Sertoli cells was reduced in low sperm producing stallions (18.6 +/- 1.3 germ cells/Sertoli cell) compared with that of high sperm producing stallions (25.4 +/- 1.3 germ cells/Sertoli cell; P < 0.001). The conversion from (yield between) early to late primary spermatocytes and round to elongated spermatids was less efficient for the low sperm producing stallions (P < 0.05). Increased germ cell degeneration during early meiosis and spermiogenesis and reduced germ cell:Sertoli cell ratio was associated with low daily sperm production. These findings can be explained either by a compromised ability of the Sertoli cells to support germ cell division and/or maturation or the presence of defects in germ cells that predisposed them to degeneration.     

Increased germ cell degeneration during postprophase of meiosis is related to increased serum follicle-stimulating hormone concentrations and reduced daily sperm production in aged men

Aged men, known to have high serum gonadotropin levels and reduced spermatogenic potential, were used to study the relationship between serum follicle-stimulating hormone (FSH) and germ cell degeneration. Serum hormones were measured from blood obtained at autopsy. Phase-contrast cytometry was used to enumerate germ cells in homogenates of fixed testes from 13 younger (24-51 yr) and 14 aged (69-90 yr) men. The developmental steps of spermatogenesis during which germ cells degenerate were determined by comparing potential daily sperm production based on primary spermatocytes with daily sperm production based on two different types of spermatids. During spermiogenesis, there was no significant degeneration in the younger or aged men. During postprophase of meiosis, aged men had more (p less than 0.01) germ cell degeneration, significantly lower (p less than 0.05) serum testosterone, and greater (p less than 0.01) serum FSH than did younger men. Germ cell degeneration during postprophase of meiosis was negatively correlated (p less than 0.01) to daily sperm production and significantly (p less than 0.01) related to serum concentrations of FSH. As revealed in these aged men, meiotic germ cell degeneration has a direct effect on daily sperm production and is significantly related to serum FSH concentrations.     

Testicular measurements and reproductive characteristics in stallions.

Factors affecting testicular measurements in situ and the relationships among the measurements and various reproductive characteristics were studied using data from 48 stallions. Mean values during the breeding season are provided for scrotal width, widths and lengths of individual testes, combined weight of testicular parenchyma, daily sperm production and daily sperm output. Testicular measurements were highly repeatable from day to day and for repeated measurements on a given day; technician provided the largest source of variation in the measurements of a given stallion. Age significantly affected all testicular measurements; testicular size for 2- to 3-year-old stallions did not differ (P greater than 0.05) from that for 4- to 6-year-olds, but was smaller (P less than 0.05) than testicular size of stallions greater than or equal to 7 years old. Scrotal width was correlated (P less than 0.01) with daily sperm production (r = 0.75) and daily sperm output (r = 0.55) and was generally the most repeatable measurement.     

Flow cytometry for assessing the efficacy of interspecific gynogenesis induction in sturgeon

The efficacy of ploidy analysis for separating progeny of Siberian sturgeon Acipenser baerii after induced gynogenesis was demonstrated using sperm of a paternal species differing in ploidy level from the maternal species. Gynogenesis was induced in tetraploid A. baerii with UV‐C irradiated sperm from the diploid sterlet Acipenser ruthenus and vice‐versa. The success of sperm UV irradiation and diploidy restoration by heat‐shock was estimated based on the ploidy level of progeny, confirmed by microsatellite parentage assignment. Hatching rates of interspecific gynogenotes were comparable with rates reported for gynogenesis induction using sperm and eggs of the same species. Juvenile mortality was similar to that observed in the control hybrids. The efficiency and reliability of this method may foster its use for production of gynogenotes in aquaculture, potentially allowing interspecific gynogenesis to replace intraspecific.     

Peripuberal sexual development of Pantaneiro stallions

Pantaneiro horses are a breed native to flood plains of Brazil, where they thrive with little human interference. The aims of this study were to characterize age-associated changes in testicular size, serum testosterone and sexual behavior and to determine age at puberty as well as to evaluate daily sperm production in the Pantaneiro stallion. After weaning the males were kept in bachelor groups away from the females, in a separated area in the natural environment of flood plains. Infantile period ended at approximately 14.4 m.o. of age. Sexual interest and breeding capability first appeared between the ages of 15.6 to 27.5 m.o. The transition from prepuberal to postpuberal histological stage, occurred at approximately 27.8 m.o. of age. All animals were in the postpuberal period at 38.5 m.o. of age. Daily sperm production estimated with testicle homogenate, at 38.5 m.o. of age was low (1.4603 +/- 0.48 x 10(9) sperm) and serum testosterone levels were similar to adult levels by 27.8 m.o. In conclusion the 2 y old Pantaneiro stallions showed full sexual behavior and had adult testosterone levels, but at this age, the stage of development of the seminiferous epithelium was variable and the efficiency of sperm production was still low.     

Genetic correlations between production and semen traits in pig

Genetic correlations between production traits (average daily gain from birth till the end of the field test and ultrasonically predicted lean meat content at the end of the field test) and semen traits (semen volume, sperm concentration, motility, percentage of abnormal spermatozoa, total number of spermatozoa and number of functional spermatozoa) were estimated from a large dataset (44 500 observations for production traits and more than 150 000 ejaculates from 2077 boars). The boars belonged to the breeds Duroc, Piétrain and Large White or were crossbreds between them. All estimated genetic correlations were low (maximal absolute value 0.13). Therefore, selection on production traits is expected to have only low effects on semen traits.     

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.     

Sperm production, testicular size, serum gonadotropins and testosterone levels in Merino and Corriedale breeds

The relationships between testis size, hormone secretion and sperm production were studied during the spring (December) and autumn (May) in rams of two breeds with different breeding seasons and body weights (Corriedale and Australian Merino) maintained on native pastures and under natural photoperiods in Uruguay. Blood samples were collected at 20-min intervals during a 260-360-min period in 13 rams (four Corriedale, nine Australian Merino) during the late spring and autumn. Rams were weighed and testis size was estimated by orchimetry at each time period. Sperm production was estimated during a 2-week period, 2 months before blood collection and during each week following every blood collection. There was no relationship between testicular size and sperm production measured at the same time, nor between live weight and sperm production. In contrast, testicular volume during the late spring was correlated with sperm production in the autumn (r = 0.65; P = 0.02). The autumn serum LH was higher in Corriedale than in Merino rams. LH pulsatility was unaffected by season, but LH pulse frequency tended to be higher in Corriedale than in Merino rams, particularly in the late spring (2.37 versus 1.56 pulses/6 h; P = 0.08). Serum testosterone concentration was similar in both breeds and seasons. FSH levels were higher in the late spring than in the autumn in both breeds (Corriedale: 2.83 +/- 0.48 versus 2.17 +/- 0.24 ng x mL(-1); Merino: 2.23 +/- 0.24 versus 1.88 +/- 0.17 ng x mL(-1)). FSH and testosterone concentrations during the late spring were positively correlated with autumn sperm production (P = 0.07 and P = 0.03, respectively). In conclusion, the present experiment suggests that LH secretion is not a good parameter for the prediction of sperm production. In contrast, in our conditions (breeds and native pastures) testicular size and testosterone or FSH concentrations from the late spring may be used to predict sperm production in the autumn.     

The development of puberty and sexual maturity in the Australian Swamp buffalo bull

Testes from 47 juvenile Swamp buffalo bulls were examined for puberty and sexual maturity histologically and daily sperm production per gram of testis parenchyma was determined by enumeration of elongated spermatids in homogenates of testis parenchyma. Puberty was defined as the attainment of a daily sperm production per gram of testis parenchyma >0.5 x 10(6). In most bulls, puberty is attained by 24 mo of age, when scrotal circumference (SC) is approximately 16 cm, and liveweight exceeds 135 kg. Sexual maturity was defined as the attainment of adult levels of daily sperm production per gram of testis parenchyma (14 x 10(6)). In most bulls, this occurs at 30 to 33 mo of age, when SC is in the 17-to 20-cm range, and liveweight generally exceeds 250 kg. There was marked individual variation in age, liveweight and SC at both puberty and sexual maturity.     

一种与受精有关的人精子膜蛋白（BS－17）的分离纯化

本文用盐分级分离,ＭｏｎｏＱＦＰＬＣ及ＳＤＳ－聚丙烯酰胺凝胶电泳（ＳＤＳ－ＰＡＧＥ）等方法从人精子ＣＨＡＰＳ抽提液中分离纯化出一种与不育病人血清中抗精子抗体发生特异反应的ＢＳ－１７人精子膜蛋白。该蛋白为一糖蛋白,分子量为１７．５５±２．１５ｋＤ,等电点为５．６５,中性己糖含量为１６．６７％。在人精子上主要分布于顶体区域,不同于已有报导的人精子膜蛋白。在体外实验中抗ＢＳ－１７多克隆血清可以显著影响人精子的获能（ｐ＜０．０２５）和对去透明带仓鼠卵的穿透（ｐ＜０．００５）,但不影响人精子运动性及与去透明酯酸带仓鼠卵的结合。小鼠体内被动免疫实验结果证明抗ＢＳ－１７多抗血清具有明显地抑制受精的功能（ｐ＜０．００１）。     

SPERM MIXING IN THE COCKROACH DIPLOPTERA PUNCTATA

Females of the viviparous cockroach Diploptera punctata store sperm from their first mating, and do not remate until after giving birth to their first batch of young. The irradiated male technique was used to determine the outcome of sperm competition in the second batch of eggs of females mated sequentially to normal and irradiated males. It is estimated that the second male to mate with a female fertilizes approximately two thirds of the eggs in a female's second batch of eggs. Direct evidence for sperm mixing was obtained. Undeveloped eggs (fertilized by irradiated sperm) and developing embryos (fertilized by normal sperm) were found interspersed throughout oothecae that were extruded from females, demonstrating that normal and irradiated sperm were released from the spermathecae at oviposition and that they competed for fertilizations.     

Mating tactics in external fertilizers when sperm is limited

Among externally fertilizing animals in aquatic habitats, theproportion of a female's egg clutch that is successfully fertilizedoften falls below 100%. In many such species, particularly incoral reef fishes, males spawn daily at high frequencies, oftenwith little or no sperm competition. A major evolutionary problemfor such males is how best to allocate sperm over successivespawns. Females face the problem of ensuring complete fertilizationof their egg clutch. Here we model male and female mating tacticswhen daily sperm production is limited and with various assumptionsconcerning how differences in the number of sperm released duringa mating influence the number of eggs fertilized. The modelsreveal conditions under which males can maximize daily reproductivesuccess, either by releasing a fixed number of sperm duringall successive spawns or by matching sperm numbers to the clutchsize of their mates. These patterns of sperm allocation exertdifferent pressures on females, which may respond evolutionarilyby developing various mating tactics of their own.     

Mating success of male guppy <Emphasis Type="Italic">Poecilia reticulata</Emphasis> in the wild

To understand how the diversity among male sexual traits is maintained despite directional female choice for attractive traits, it is important to study male reproductive success in each reproductive episode. Male reproductive success is indeed the comprehensive result of several processes such as mate choice, mating, and fertilization. In this study, male mating success was estimated in a wild guppy Poecilia reticulata population of Hiji River, Okinawa Island, in southern Japan. The mating success of males was estimated as the percentage of sperm transferred in relation to the total sperm reserve. In a preliminary experiment, it was confirmed that the sperm reserves of males were partly replenished after 12 h and fully replenished after 72 h, when all sperm were released. In addition, the results of investigation in the wild population revealed that approximately 20% of males had no sperm reserves at all, although their sperm reserves should have been replenished by sexual isolation. Male sexual traits such as body size or color pattern did not affect the percentage of sperm transferred. Results from this study provide important insights into male sperm transfer ability and sperm production in this population. However, the high frequency of male sperm-transfer success estimated in this study should to be taken with caution, and whether it is due to differences between wild and laboratory conditions, sex ratio or the rates of multiple matings by females in the wild population remain to be fully explored.     

Identification and expression of boar sperm proteins in the reproductive tract that interact with antibodies in serum from an infertile woman

Serum designated as IS obtained from a young healthy infertile woman induced a head-to-head agglutination of ejaculated boar sperm. The immunoglobulin G (IgG) prepared from IS localized to the acrosomal region of the sperm head obtained from the corpus and cauda epididymis as determined by an indirect immunofluorescent method. The IgG interacted with a boar sperm protein with an estimated molecular weight of 45-kDa, determined by sodium dodecyl sulfate-polyacrylamide gel electrophoretic (SDS-PAGE) immunoblotting technique. However, the IgG did not interact with proteins extracted from sperm obtained from the testis and caput epididymis or from non-gonadal tissues including liver, kidney, spleen, muscle and serum. The IgG interacted with additional proteins of about 75- and 38-kDa present in the corpus and cauda epididymal fluids but not those in the caput epididymal fluid. The staining intensity of the 75-kDa band was reduced and that of the 38-kDa was nullified with ejaculated seminal plasma proteins. The interacting proteins were adsorbed when chromatographed on Concanavalin A Sepharose column, suggesting that they are glycoproteins.     

Predicting variation in sperm precedence

Sperm competition theory predicts that males are adapted for success in sperm competition by the production of large numbers of sperm. This is supported by both inter- and intraspecific studies showing that males mating under high sperm competition risk increase investment in sperm production. Such an increase in sperm production is an advantage if sperm mix randomly or if sperm displacement occurs. When two males mate with the same female, the measurement of the proportion of eggs fertilized by the second male to mate (termed P₂) has been used to help elucidate sperm competition mechanisms. P₂ is usually quoted as a mean value, with little attention being paid to its variance, although P₂ estimates are notoriously variable. By predicting an expected variance for P₂, additional information on sperm competition mechanisms may be obtained. Here we present a technique for analysing the variance in P₂ when a given mechanism of P₂ is assumed. We apply this technique to P₂ data collected from Plodia interpunctella (Lepidoptera, Pyralidae), assuming a ''fair raffle'' mechanism of sperm competition. We compare observed distributions of P₂ with theoretical distributions generated assuming random mixing of two ejaculates drawn randomly from a population of known mean and variance in sperm numbers. Ejaculates of known size were obtained by counting the number of sperm ejaculated by males mating for the first (large ejaculate) or second (small ejaculate) time. Females either received two small or one small and one large ejaculate, and the distribution of P₂ (estimated using the sterile male technique) was compared with our theoretical predictions. The observed variance in P₂ was greater than our model prediction, thus we conclude that sperm from P. interpunctella do not mix randomly before fertilization. <br>     

Gonadal and extragonadal sperm reserves in Boran and Boran x Friesian bulls raised on two planes of nutrition in the Highlands of Ethiopia

Gonadal and extragonadal sperm reserves were determined in testicular and epididymal tissues obtained from Boran (n=10) and Boran x Friesian (n=12) bulls fed either a high or low plane nutrition diet for a 1-year period. The bulls were 32 months of age at castration. Mean (+/-SEM) daily body weight gains over a 1-year period were 776+/-34 and 264+/-34 g/day (P<0.001) for bulls on high and low nutrition, and their respective body weights at castration were 458+/-17 and 276+/-17 kg (P<0.01). Mean body weights did not differ between Boran and Boran x Friesian bulls. Mean scrotal circumference measurements were 32.1+/-0.6 and 28.8+/-0.6 cm for the high and low planes of nutrition (P<0.01) and 31.8+/-0.7 and 29.2+/-0.6 cm for the Boran and the Boran x Friesian bulls (P<0.05). Paired testes and epididymal weights averaged 432+/-22 and 313+/-22 g (P<0.01) and 46.3+/-2.0 and 32.5+/-2.0 g (P<0.001) for bulls on the high and low planes of nutrition, respectively. Boran x Friesian bulls had significantly heavier (P<0.05) testes, but epididymal weithts did not differ between breeds. Although daily sperm production per gram was not influenced by either plane of nutrition or breed, daily sperm production differed between high (5.3 x 10(9)) and low nutrition (2.9 x 10(9)) bulls (P<0.001) and between Boran (4.6 x 10(9)) and Boran x Friesian (3.5 x 10(9)) bulls (P<0.01). Extragonadal sperm reserves were significantly higher in high than in low nutrition bulls (13.1 x 10(9) vs 6.9 x 10(9); P<0.001) and in Boran than Boran x Friesian bulls (12.9 x 10(9) vs 7.1 x 10(9); P<0.01). The cauda epididymis contributed 50 to 54% to the total epididymal sperm reserves. It was concluded that the plane of nutrition influenced growth rates and testes and epididymal weights, and it improved gonadal and extragonadal sperm reserves in young Boran and Boran x Friesian bulls.     

Extraction of photosynthesis-irradiance parameters from phytoplankton production data: demonstration in various aquatic systems

A method is presented for extraction of the photosynthesis-responseparameters from profiles of phytoplankton production. The procedure,previously proposed but not tested, is implemented here in varioustypes of aquatic system and a protocol is established for itsuse. Values of daily primary production integrated over thephotic zone were estimated from in situ or simulated in situincubations in four coastal and open-ocean marine systems, andfrom photosynthesis-irradiance (P–E) curves in the afore-mentionedmarine systems, as well as in two freshwater systems. The slopeof the measured daily water-column production (normalised towater-column chlorophyll a biomass) plotted against the dailyincident irradiance was variable from system to system (0.09to 0.60), showing a broader range than previously reported values.Using an iterative procedure, we estimated the photosyntheticparameters from this linear relationship. Generally, estimatedvalues lie within the 95% confidence interval of the photosyntheticparameters obtained from the P–E curves, showing thatthe estimates agree well with measurements. The new method,based on the photophysiological response of the phytoplanktoncommunity, provides a way to enhance our ability to computeprimary production from remote sensing of ocean colour.