I examined the role of vibrations in predator-induced early hatching of red-eyed treefrogs, Agalychnis callidryas. The arboreal eggs of A. callidryas hatch up to 30% early if attacked by egg-eating snakes. This induced hatching is a behavioural response that occurs once snakes begin physically disturbing the clutch, and is sufficiently rapid to allow most embryos to escape. Other intense but be...

BACKGROUND The object of this study was to evaluate the efficacy of laser assisted hatching (LAH) of embryos on implantation and pregnancy rates of a selected group of infertility patients. METHODS A total of 322 cycles using LAH was undertaken in our Centre between June 1998 and September 1999. Patients were offered LAH if they fell in either one or more of the following categories: (i) Pati...

Simultaneously dependent siblings often compete for parentally provided resources. This competition may lead to mortality, the probability of which may be a function, in part, of the individual offspring's production order. In birds, serial ovulation followed by hatching asynchrony of simultaneous dependents leads to differences in post-hatching survival that largely depend on ovulation (laying...

The physiological role of the embryonic external gills in anurans is equivocal. In some species, diffusion alone is clearly sufficient to supply oxygen throughout the embryonic period. In others, morphological elaboration and environmental regulation of the external gills suggest functional importance. Since oxygen stress is a common trigger of hatching, I examined the relationships among hatch...

The age structures of populations of African annual Nothobranchius spp. were examined for the first time. Daily increments in sagittal otoliths of Nothobranchius furzeri, Nothobranchius kadleci, Nothobranchius orthonotus and Nothobranchius rachovii from southern and central Mozambique were used for age determination. Four hypotheses were tested: (1) timing of hatching is consistent with the cal...

Meloidogyne incognita egg masses were immersed in different concentrations of six volaule fatty acids to bioassay their toxic effect on embryonic development and hatching. Exposure to a 250 ppm aqueous solution of volatile fatty, acids completely suppressed egg hatching within 48 hours. When exposed to a 125 ppm concentration hatching was reduced 75 % by acetic acid, 91% by propionic acid, 23% ...

The optimum dose of ultraviolet (UV) irradiation to produce gynogenetic Caspian salmon, Salmo trutta caspius, with emphasis on the "Hertwig effect" and photoreactivation (PR) were investigated. The sperm of Caspian salmon was irradiated with UV at 2010 ? 200 ?w.cm-2 in different times including 0, 1, 3, 5, 8, 10, 15, 20, 25, 35 and 45 min and was allowed to fertilize normal ova; the fertilizati...

BACKGROUND Assisted hatching (AH) is a manipulation of zona pellucida aiming to facilitate embryo implantation. METHODS Systematic review and meta-analysis of medical literature was used to evaluate the effect of AH on assisted reproduction outcomes: clinical pregnancy, live birth, multiple pregnancy and miscarriage. Additional analysis was performed in these subgroups: (i) fresh embryos tran...

Embryos of good, fair and poor quality were collected from superovulated cows and subjected to zona cutting (ZC) treatment using a needle under either an inverted microscope or a stereomicroscope. One (single transfer) or 2 (twin transfer) embryos with or without prior ZC treatment were transferred nonsurgically to recipients. Without the ZC treatment, lower embryonic quality resulted in lower ...