Cholesterol, being the starting point of steroid hormone synthesis, is a long known modulator of both female and male reproductive physiology especially at the level of the gonads and the impact cholesterol has on gametogenesis. Less is known about the effects cholesterol homeostasis may have on postgonadic reproductive functions. Lately, several data have been reported showing how imbalanced c...

Rats were surgically made bilaterally cryptorchid and after 4-8 days the testes were returned to the scrotum. After 70 days fertility was tested by pairing with females. Fertility was restored in 5/6 rats with testes cryptorchid for 4 or 5 days, but only 2/9 were fertile when the duration of cryptorchidism was 6-8 days. The sterility was due to irreversible degeneration of the spermatogonial st...

Because of the high concentration of nutrients in human urine, its utilization as an organic fertilizer has been notable throughout history. However, the nitrogen compounds in urine are not stable. Therefore, to convert urine into a suitable fertilizer, it is important to stabilize and adjust unstable nitrogen compounds such as ammonia. Because nitrification can influence the nitrogen profile, ...

HE theoretical aspects of diploid populations where all reproduction is by self-fertilization have been considered by several workers (ANDERSON and KEMPTHORNE 1954; COCKERHAM 1954,1963 ; HORNER, COMSTOCK and ROBINSON 1954; DEMPSTER 1955; KEMPTHORNE 1956, 1957, 1963; HORNER and WEBER 1956; GATES, COMSTOCK and ROBINSON 1957; HANSON and WEBER 1961). Several of these papers have indicated parametri...

Progressively motile spermatozoa were present in 42/47 (89%) of post-vasectomy specimens, and in 16 of 24 samples (66%) demonstrable fertilizing potential could be detected in the zona-free hamster egg assay. The mean +/- s.e.m. post-vasectomy penetration rate of 20.6 +/- 6.0% was, however, significantly lower (P less than 0.001) than the pre-vasectomy value of 49.7 +/- 6.4%. After vasectomy th...

Little is known about the reproductive behaviors and the actual outcomes of mating attempts in the gopher tortoise (Gopherus polyphemus). We examined the mating system and reproductive behaviors of a population of gopher tortoises in central Florida. Using microsatellite markers, we assigned fathers to the offspring of seven clutches and determined that multiple fathers were present in two of t...

Caspases are central components in the apoptosis signaling cascade. The family of cysteine proteases transduces and enhances the apoptosis signal, and activation of effector caspases results in controlled cellular degradation. Although initially the presence of caspases in spermatozoa was controversially discussed in recent years, many studies demonstrated their activation in male germ cells. A...

Reproductive-isolating mechanisms between nascent species may involve sperm-egg recognition and have been best described in externally fertilizing organisms where such recognition is essential in preventing undesirable fertilizations. However, reproductive barriers in internally fertilizing species differ in significant ways, and a direct role for sperm-egg interactions has yet to be demonstrat...

Abstract. The current paper has presented the results of applying various terms and types nitrogen additional fertilizing in cultivation winter bread wheat. purpose study was to establish productivity grain quality wheat sown after sunflower, when using fertilizing. Ammophos ammonium sulfate were applied under seedbed cultivation; nitrate, urea carbamide-ammonia mixture used as at different per...