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Topic:Spermatogenesis
Spermatogenesis in horses is the process by which spermatozoa are produced in the testes. This complex sequence of events involves the proliferation and differentiation of germ cells, supported by Sertoli cells and influenced by hormonal regulation. Key stages include spermatogonial mitosis, meiosis, and spermiogenesis, resulting in the formation of mature sperm cells. Hormones such as testosterone and follicle-stimulating hormone (FSH) are integral to regulating this process. This topic encompasses research studies and scholarly articles that explore the mechanisms, hormonal influences, and factors affecting spermatogenesis in horses, as well as its implications for equine reproduction and breeding management.
[Seasonal changes in spermatozoas and fertility of stallions in the tropics]. An attempt was made to express the relationship of spermiological characteristics with the fertility on the basis of seasonal variability of the fertility of stallions and of the ejaculate quality. A positive correlation between the activity of spermatozoa and the fertility ensues from the values of correlation coefficients. There is a negative correlation between the fertility and the concentration of citric acid. In the other characteristics, i.e. in the production of spermatozoa, volume of gel substance, pH, ergothioneine concentration, polarographic and hemolytic activity, the correlation ...
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 ...
Cytogenetic and clinical findings in mares with gonadal dysgenesis. Gonadal dysgenesis in the mare is associated with several different karyotypes, including sex chromosome aneuploidy (63,X; 63,X/64,XX; 63,X/64,XY or 65,XXX), the normal male complement (64,XY) and autosomal deletion (64,XX?del2q-). The 63,X is the most common karyotype found in gonadal dysgenesis. Aneuploid cases probably represent spontaneous chromosome non-disjunction during oogenesis, spermatogenesis or early embryonic development. Cases with XY or autosomal deletion may be inherited defects or of spontaneous origin.
Effect of successive ejaculation on stallion seminal characteristics. Five ejaculates were collected at hourly intervals from 32 sexually rested stallions. Gel volume, total seminal volume, sperm concentration and spermatozoa per ejaculate declined (P less than 0.01) from the first to the second or third ejaculate. Gel-free seminal volume or percentage of motile spermatozoa did not vary (P less than 0.05) among ejaculates. Ejaculates from 2- to 3-year-old stallions contained less volume and fewer spermatozoa than those from 9- to 16-year-old stallions. Regardless of the stallion's age the first, first 2, first 3 and first 4 ejaculates represented 50, 74, 86 and ...
Influence of exogenous testosterone on sperm production, seminal quality and libido of stallions. The effect of exogenous testosterone on sperm production, seminal quality and libido was studied in 24 stallions. Based on pretreatment data, a stallion was assigned to 1 of 3 groups each containing 8 animals. One member of each group received 0 (Group 1), 50 (Group 2), or 200 micrograms (Group 3) testosterone propionate per kg body weight every 2 days for 88 days. The lower dose of testosterone had no significant effect on most of the parameters studied: the higher dose depressed total scrotal width at Day 90 post-treatment (P less than 0.01), total spermatozoa ejaculated between Days 60 and ...
Effects of age and frequency of ejaculation on sperm production and extragonadal sperm reserves in stallions. Extragonadal reserves totalled 89 X 10(9) spermatozoa for 5--16-year-old sexually rested stallions and 60 X 10(9) for 2--4-year-olds. Regardless of age, the cauda epididymidis contained 62% of the total reserves and the vas deferens, including the ampulla, contained 7% of the total reserves of spermatozoa. The caput plus corpus epididymidis from 5--16-year-old stallions (N = 41) contained 14.9 X 10(9) spermatozoa per side as compared (P less than 0.01) to 8.5 X 10(9) for 2--4-year olds (N = 30). Frequency of ejaculation did not influence the number of spermatozoa found in caput plus corpus epi...
[Morphology of live and dead spermatozoa of stallions (author’s transl)]. Examination of 539 ejaculates of stallions of various breeds showed that approximately 60 per cent of the spermatozoa were completely normal morphologically. Of these morphologically normal spermatozoa, 13 per cent were dead. The total proportion of live spermatozoa was 75 per cent, 32 per cent being obviously abnormal (22 per cent of live and 10 per cent of dead spermatozoa). Separated heads (normal as well as abnormal) were significantly more common among dead spermatozoa. Protoplasmic droplets (both at the neck and at the end of the middle piece) were mainly present in live spermatozoa. As ...
Scanning electrons and light microscopy of the equine seminiferous tubule. Changes within the equine seminiferous tubules during the cycle of the seminiferous epithelium were studied light and scanning electron microscopy (SEM). Once observed with SEM, tubules were sectioned and staged using light microscopy. As viewed by SEM, the weblike, spongy cytoplasm of germ cells or Sertoli cells in stages I and II extended over the entire height of the germinal epithelium. The cytoplasm of the basal portion of the germinal epithelium in stages III to VIII was similar to that in stages I and II. However, the cytoplasm which occupied the luminal third of the epithelium in stage...
Current status of semen preservation in the ram, boar and stallion. From the studies cited it was concluded that short and long term preservation of stallion semen has encountered major obstacles. Fertilizing capacity of extended or extended and cooled spermatozoa has been impaired. With the hydrogen ion extenders, the fertility was depressed either with or without glycerol when the semen was inseminated immediately after extension. With the cream-gel extender, fertility was not impaired when inseminated immediately after extension, but was impaired after storage at 5 C for 24 hr or in the presence of glycerol. The fertilizing capacity of extended frozen sperm...
Factors influencing the quantity and quality of semen harvested from bulls, rams, boars and stallions. Several inherited conditions associated with testicular defects, abnormal spermatogenesis and morphologically abnormal sperm have been found. These usually are controlled by single gene pairs. A notable exception is testicular size, with heritability in young bulls ranging from .42 to .88. Testicular size directly affects sperm output potential. The major contributor to variation in semen quality is the environment. Environmental effects may be temporary or permanent. Permanent effects occurring during prenatal and prepubertal periods and temporary or permanent factors acting after spermatogen...
Ultrastructural observations suggesting merocrine secretion in the initial segment of the mammalian epididymis. Principal cells in the initial segment of the epididymis in horses, cattle, pigs, sheep, dogs, cats, and rabbits have an abundant, partly rough, endoplasmic reticulum and a large Golgi complex. Small vacuoles with opaque content seem to be formed by the Golgi complex and move to the cell apex, where they empty their contents into the lumen by a merocrine mechanism.
[Phantoms for the collection of genital secretions in stallions]. Practical experiences of the phantom method for collection of genital secretions from stallions are reported. Taking a phantom used in the Richard-Götze-Haus Tierärztliche Hochschule Hannover as a prototype two further models slightly modified have been constructed, baring a flat hollow in the right side of the caudal phantom body for manual inserting of the Artificial Vagina. These three models fulfill four important conditions for routine use: (1) sufficient sexual attractivity for the stallions; 80-85% successful collections of presecretions out of a total of 1050 using the dummy and 70% ...
Reproductive function in stallions treated with cambendazole. Twenty stallions were used to determine if the anthelmintic cambendazole affected seminal characteristics, spermatogenesis, concentration of testosterone in blood serum, or weights of the reproductive orgrans. With minor exceptions, significant differences were not found between values for 10 control and 10 stallions treated with a single oral dose (40 mg/kg body weight) of cambendazole. The treatment did not affect reproductive function and it was concluded that the drug should have no effect on the fertility of stallions.
Reproductive physiology of the stallion. VIII. Artificial photoperiod, collection interval and seminal characteristics, sexual behavior and concentrations of LH and testosterone in serum. Stallions were subjected to a gradually increasing photoperiod beginning on October 15, 1973. The maximum artificial daylength (16 hr) was imposed on February 8, 1974, and maintained until October 6, 1974. Two ejaculates were collected from each of five treated and four control stallions weekly, with an interval of 24 hr between die paired ejaculates on the first and alternate weeks, and an interval of 1 hr on the second and alternate weeks. During summer, stallions subjected to the artificial photoperiod produced less (P<.05) gel-free semen and gel per ejaculate and had more (P<.05) spermatoz...
