Large Numbers Of Sperm Research Articles

Correlation between sperm "redundancy" and chiasma frequency.

MOST male animals produce a large number of spermatozoa, whereas their females produce a relatively small number of eggs. Classically, this has been related to dilution problems in the external fertilizing medium of the female genital tract, and to synergic effects of super-numerary sperm in dissolving egg membranes or stimulating the female tract. The wide range of sperm redundancy (from 2.0 to 2 × 1010), however, suggested that another more immediate cause may be responsible. If a multiple process during spermiogenesis regularly fails in a proportion of attempts, then the number of “perfect” sperm may only be a small proportion of the total, the total produced being related logarithmically to the number of such faulty multiple processes in the production of each sperm. For example, if half such processes are faulty, then it is to be expected that where P is the number of processes in the production of one sperm, r is the sperm redundancy, R is the sperm number divided by the zygote number for one copulation, and n is the (small) number of “perfect” sperm still required for each egg to meet the exigencies of random collision paths. It was found (Fig. 1) that for those few organisms for which both chiasma frequency and sperm redundancy have been investigated, a logarithmic correlation of the form fits the points well. This may be taken to imply that about one in three chiasmata has a result which renders the resultant sperm less than “perfect”.

Longevity of spermatozoa in the reproductive tract of the bitch.

Summary. Survival of spermatozoa in the reproductive tract of the bitch was studied by examination of the female genitalia at measured intervals after copulation. Motile spermatozoa were found in the lumen of the uterus in undiminished concentrations for 4 to 6 days after copulation; numbers progressively declined but motile spermatozoa were observed as late as 268 hr after copulation. Clusters of spermatozoa were observed in a high percentage of the uterine glands. The disappearance of spermatozoa was associated with the onset of metoestrus, not with time in the uterus. Bitches bred late in oestrus and examined in metroestrus had few spermatozoa compared with bitches examined in oestrus at a comparable time after copulation. Large numbers of spermatozoa were never found in the oviducts or ovarian bursae; they were consistently found here between 20 and 40 hr after copulation, a single observation showed spermatozoa in the oviducts at 168 hours. Tubal ova were recovered from eight bitches in metoestrus, in five cleavage had begun; tubal ova were recovered from four bitches in oestrus, none had undergone cleavage. Examination of the ovaries indicated that ovulation most commonly occurred within 48 hr after the onset of oestrus.

Feulgen-DNA content of individual bull spermatozoa

D URING Feulgen-DNA measurements on individual bull spermatozoa with a view on establishing a contingent correlation between the spread of the values found within a sample and the fertilizing capacity of the semen we noted, first, that values obtained with our method showed a considerably lower spread than had been found previously and, secondly, that the results are compatible with the presence within the samples of two populations, differing some 3 per cent in DNA content. The present paper deals with an analysis of two sperm samples with respect to these observations. The cytophotometer used has been described previously [2]. It has been modified in that in the present apparatus the scanning is done in the image plane. It has been found empirically that this arrangement is less sensitive to focussing errors and allows of a slightly better resolution than that formerly employed. The standard deviation of repeated measurements on the same spermatozoon was found to amount to 1 per cent of its Feulgen-DNA content. This source of spread in measuring results will be referred to as the instrumental error. The standard Feulgen technique was employed but hydrolysis was performed in 5.5 N HCl at 2O’C ( f O.l’C). Under these circumstances, and in our material, the staining intensity is relatively independent of the hydrolysis time within the range 45-60 min. In the present investigation hydrolysis was terminated after 50 min. All baths were symmetrically agitated and every detail of the technique was rigorously standardized; nevertheless we were unable to obtain identical staining over the entire surface of 2 x 3 cm smears of semen. Within an area of a few square milimeters the spread of the values obtained on 50 spermatozoa was the same as that found in a similar area elsewhere on the same slide or on a slide treated simultaneously, but the mean of the values found in one area could differ from zero to as much as 4 per cent from that found in another area. In order to pool the measuring results obtained on a large number of spermatozoa we measured closely adjacent spermatozoa in groups of 40 or 50 and corrected for the apparently unavoidable difference in staining effectiveness between the groups by converting every group mean into 100 arbitrary units. The histograms for 760 spermatozoa from one ejaculate (P.C.), Fig. 1, and 450 spermatozoa from another bull (Joh. I.), Fig. 2, have been plotted in unit steps,

DISTRIBUTION OF SPERMATOZOA IN THE OVIDUCT AND FERTILITY IN DOMESTIC BIRDS

Summary. Semen from low-fecundity cocks, characterized by relatively large numbers of spermatozoa with abnormal morphology, poor motility and sluggish metabolism, fertilized very few eggs when inseminated mid-vaginally, but produced moderate fertility when deposited in the uterus. The percentage of pre-ovipositally dead embryos was also increased in eggs fertilized by spermatozoa from low-fecundity cocks when these were deposited directly in the uterus. Few spermatozoa from low-fecundity cocks entered and/or survived in oviducal glands, especially in those of the uterovaginal junction.

FERTILIZING LIFE OF FERRET SPERM IN THE FEMALE TRACT.

AbstractFor the determination of the fertilizing life of ferret sperm in the female tract, gonadotrophin was intraperitoneally injected to induce ovulation at various times after the deposition of epididymal sperm into the uterine horns. The animals were examined 48 or 60 hours after ovulation injection to assess the proportion of fertilized eggs, although a few of them were allowed to deliver young.Intraperitoneal injection of 50 hypophysectomized R.U. of sheep pituitary extracts or 90 I.U. of Human Chorionic Gonadotrophin invariably induced ovulation in ferrets that were in heat. Ovulation occurred about 24 to 36 hours after the administration of H.C.G. and an average of 14.5 eggs with a range of 8 to 24 eggs per animal was obtained.The average number of sperm in the cauda epididymides and the vasa deferentia of nine males was 219 millions with a range of 24 millions at the end of breeding season to 621 millions at the peak of breeding season.The percentage of total eggs that were fertilized was 73, 40, 24, 15, 3, and 0 when the ovulation injection was given at 0, 36, 72, 84, 96, and 108 hours after sperm deposition respectively. Since ovulation occurred 30 hours after ovulation injection the fertilizing life of ferret sperm in the female tract is therefore no more than 126 hours. The percentage of eggs fertilized was lower following the deposition of epididymal sperm than following mating (73% vs. 98%). There is evidence that the fertility of sperm in the female tract was higher if a large number of sperm was deposited, and that the penetration of sperm into the egg facilitated the denudation of the egg.The majority of the penetrated eggs (54 to 84%) were at the pronuclear stage 48 hours after insemination and ovulation injection (i.e., about 18 hours after ovulation), at 60 hours (30 hours after ovulation) the majority of them were either at pronuclear stage (26–100%) or at the 2‐cell stage (46–57%), and at 70 hours (40 hours after ovulation) most of them were at the 4–6 cell stage. The morphology of fertilization in the ferret and the time sequence after sperm penetration were described.

SPERM ASCENT THROUGH THE OVIDUCT OF THE HAMSTER AND RABBIT IN RELATION TO THE TIME OF OVULATION.

Summary. Female golden hamsters were mated either about 5 to 8 hr before ovulation or about 2 hr after ovulation. At various intervals after mating, a ligature was placed slightly above the intramural portion of the oviduct, thus preventing further sperm ascent. In the females mated before ovulation, the percentages of eggs fertilized, as examined 10 to 12 hr after the estimated time of ovulation, were 16·8, 39·6, 58·3 and 81·4 when oviducts were ligated 1, 2, 4 and 6 hr after mating, respectively. In the females mated after ovulation, on the other hand, 37·5 and 92·0% of eggs were fertilized following ligation of oviduct at 0·5 and 1 hr after mating, respectively. Examination of complete serial sections of oviducts fixed 1 hr after mating showed that the oviducts of females mated after ovulation contained a relatively larger number of spermatozoa in their upper reaches than those of females mated before ovulation. It is concluded that in the hamster the ascent of spermatozoa through the oviduct takes place more rapidly when females are mated after ovulation than before ovulation. When rabbits were mated 8 and 4 hr before or 2 hr after ovulation, and their utero-tubal junctions were ligated 2 hr later, the fast sperm ascent after ovulation was not demonstrated.

Insemination before and after the onset of heat in sows

Counts were made before and after fixation of the numbers of fertilised and unfertilised ova recovered from 3 mated sows, 7 unmated sows and from 34 sows inseminated at varying times before and after the onset of heat.The percentages of fertilised ova for sows inseminated the day before heat (day — 1) on the first day of heat (day 0) the second day of heat (day 1) and the third day of heat (day 2) are respectively for unfixed and fixed ova: 7·1 and 9·8, day – 1 ; 55·9 and 68·8, day 0; 63·4 and 98·2, day 1; 20·1 and 15·2, day 2. No fertilised ova were recorded from unmated sows; the percentages for mated sows were 94·3 and 95·5.It is concluded that failure of fertilisation is likely to be the greatest source of loss of fertility in inseminations made before heat and late in heat.Most ova from sows inseminated on day — 1 and from sows inseminated in day 2 had no spermatozoa on the zona pellucida. A few ova from sows inseminated on day 2 had very large numbers of spermatozoa present.It is suggested that failure of the spermatozoa to reach the site of fertilisation rather than their loss of fertilising capacity is likely to be the cause of the low fertility of early inseminations.

Freezing Bovine Semen. V. Practicability of Collecting and Freezing a Large Number of Successive Ejaculates1,2

From six to 37 successive ejaculates were collected during 12, 2-hr. depletion trials with eight dairy bulls, and used to investigate (a) the proportion of ejaculates acceptable for freezing and (b) the freezability of the acceptable ejaculates. Only ejaculates showing an initial motility of 30% or more and a minimum of 150million motile spermatozoa were frozen. On this basis, the percentage of culled ejaculates increased as the number of consecutively collected ejaculates increased. Considering the first five consecutive ejaculates, only 6.7% were culled; among the first ten consecutive ejaculates, 11.6% were culled; whereas, among all 257 ejaculates collected, 35.8% were culled. There was no significant difference in the freezability of the acceptable ejaculates among the first five or first ten individual ejaculates, and freezability was comparable with that obtained with ejaculates collected from the same bulls when on a frequency of two or six ejaculates per week. Beyond the tenth ejaculate, freezability was generally, but not significantly, poorer and collection of more than ten consecutive ejaculates probably would be of no practical value. Pooling acceptable ejaculates from a depletion trial resulted in freezability comparable to freezing the ejaculates separately. With adequate sexual preparation, the collection of six or seven consecutive ejaculates from a given bull should make available large numbers of sperm at one time, which should freeze satisfactorily.

Capacitation of rabbit spermatozoa in the uterus with special references to the reproductive phases of the female.

The capacitation of sperm (spermatozoa undergo a certain physiological change in the female tract before they are capable of fertilization) was investigated by injection of sperm into the uterus of rabbits at various reproductive phases or rabbits treated with gonadotrophin, estrogen or progesterone. Twelve hours later the injected sperm were recovered and then deposited into the top of the fallopian tubes of another rabbit that had ovulated recently. This was done to determine whether sperm so treated could fertilize the ova. Although capacitation was achieved in the uterus of immature and ovariectomized rabbits with or without the treatment of gonadotrophin or estrogen, it could not be achieved in the uterus of pseudopregnant rabbit with or without the treatment of gonadotrophin or estrogen or in the uterus of immature, ovariectomized, or estrous rabbits treated with progesterone. The inhibition of capacitation of sperm in the pseudopregnant uterus or in the uterus of rabbits treated with progesterone was not due to the poor motility of sperm, the large number of sperm, the concentration of white cells, or the possible, bacterial infection of the endometrium. However, when sperm were injected into the fallopian tubes of pseudopregnant rabbits and then recovered and deposited into the tubes of another rabbit fertilization occurred. It seems that capacitation of sperm was inhibited in the uterus under the influence of progesterone but it was not so affected in the fallopian tubes.

INHIBITORS OF HYALURONIDASE IN BLOOD SERA AND THEIR EFFECT ON FOLLICLE CELL DISPERSALM1

SINCE HYALURONIDASE, an enzyme prepared from mammalian testes or spermatozoa, was found capable of readily dispersing the follicle cells of freshly ovulated mammalian ova without apparent injury to the egg (McClean and Rowlands, 1942; Fekete and Duran- Reynals, 1943; Leonard and Kurzrok, 1945), new concepts on problems of fertility and sterility have arisen. These observations have led to the suggestion that the relatively large numbers of sperm in an ejaculate are necessary to attain a sufficiently high concentration of hyaluronidase in order that the tightly adhering follicle cells can be removed for sperm penetration and in time before degeneration of the ovum. Rowlands (1944) succeeded in artificially inseminating and fertilizing rabbits with dilute sperm suspensions provided the enzyme from killed sperm was added. Without the enzyme, no fertilization occurred. Leonard and Kurzrok (1945) reported that it was possible to artificially inseminate and fertilize women by adding bull-testis hyaluronidase to...

Capacity of Hyaluronidase to Increase the Fertilizing Power of Sperm

THE capacity of hyaluronidase to liquefy the highly viscous gel which cements the cumulus cells around the unfertilized tubal egg of the rat was described by McClean and Rowlands1, and confirmed in the mouse by Fekete and Duran-Reynals2 shortly afterwards. We suggested that the gel is hyaluronic acid similar to that in synovial fluid and, to enable its disintegration to occur as a preliminary to fertilization, a certain unspecified concentration of hyaluronidase must be established by the sperm in the vicinity of the egg. The fact that intromission of such a large number of sperm is necessary to ensure fertilization, therefore, may well be related not only to the safe passage of one or more sperm into the Fallopian tube but also, and possibly more especially, to the establishment of this requisite concentration of enzyme. Some preliminary experiments., which are described below, have now been carried out in rabbits to investigate the capacity of hyaluronidase to increase the fertilizing power of dilute sperm suspensions.

A Study of the Function of the Epididymis

A Study of the Function of the Epididymis

Egg-Follicle of Culex

1. When a newly emerged mosquito is fed on food other than blood, the nuclei of all the cells of an egg-follicle pass through the synizesis stage. After three to four days feeding on artificial food the nuclei of the nurse-cells become differentiated from the nucleus of the oocyte. The egg-follicle does not develop further on artificial food. 2. A feed on blood is essential for the deposition of yolk and the secretion of membranes. 3. The nucleolus of the oocyte is an amphinucleolus and consists of proteids and nucleinic acid as shown by the very interesting changes in its staining capacity. 4. The irregularity of the nuclear membrane of the germinal vesicle is due to the pressure of coarse yolk-granules and cannot be interpreted either as indicating a direct participation of the nucleus in the formation of yolk or as an artifact due to 5. The yolk-granules do not arise necessarily first in the neighbourhood of the nucleus. 6. In the germinal-vesicle stage the nucleus enlarges considerably in size, and its chromatin is present in the form of very small granules. 7. When the oocyte has almost reached its full size the germinal vesicle shrinks considerably in size and takes its position at the anterior end. The ‘definitive nucleus’ from which the polar bodies and the female pronucleus doubtless arise appears in the centre of the germinal vesicle. The ‘definitive nucleus’ has a very definite membrane within which is a deeply basophil mass of chromatin. 8. The outer portion of the germinal vesicle merges into the cytoplasm of the oocyte. It is difficult to associate this with the nutrition of the oocyte as it takes place when the oocyte has almost reached its full size and yolk-formation is practically complete. 9. The structure and the development of the chorion, the vitelline membrane, the striated collar, and the micropylar apparatus have been described. 10. The micropylar tube develops a short time before fertilization. It degenerates immediately after the egg is laid and is absent in the laid egg. It is thus that it has escaped notice so long. 11. As a rule copulation does not take place in captivity, but in two cases I observed that the spermatheceae of females confined with males contained a large number of spermatozoa.