Preferable location of chromosomes 1, 29, and X in bovine spermatozoa.

Chromosome positioning in sperm nucleus may have a functional significance by influencing the sequence of post-fertilization events. In this study we present data on preferential locations of chromosomes 1, 29 and X in spermatozoa. Here we demonstrate that the position of X chromosome in the sperm nucleus is more restricted as compared to the position of chromosome 1, which is about of the same size.

Positioning of chromosomes in human spermatozoa is determined by ordered centromere arrangement.

The intranuclear positioning of chromosomes (CHRs) is a well-documented fact; however, mechanisms directing such ordering remain unclear. Unlike somatic cells, human spermatozoa contain distinct spatial markers and have asymmetric nuclei which make them a unique model for localizing CHR territories and matching peri-centromere domains. In this study, we established statistically preferential longitudinal and lateral positioning for eight CHRs.

Protamine withdrawal from human sperm nuclei following heterologous ICSI into hamster oocytes.

During late stages of spermatogenesis in mammals, most histones bound to DNA are replaced by protamines (PRM), which results in formation of supercondensed and genetically inert sperm chromatin. At fertilization, mature spermatozoon penetrates oocyte and chromatin is remodeled "back" from nucleoprotamine to nucleohistone state. While being crucial for activation of male genome and ultimately for initiation of embryonic development, this process is poorly studied, especially in humans.

Kinetics of human male pronuclear development in a heterologous ICSI model.

Purpose: To evaluate human sperm nuclear chromatin decondensation in a heterologous ICSI system using hamster ova injected with human sperm.

Materials And Methods: Frozen hamster oocytes were injected with Triton X-100 treated sperm and fixed at different time points post ICSI. Oocytes injected with non-treated sperm served as controls.

Reorganisation of human sperm nuclear architecture during formation of pronuclei in a model system.

By fertilisation, two terminally differentiated cells, namely the egg and spermatozoon, are combined to create a totipotent zygote. During this process, the inactive sperm nucleus is transformed into a functional male pronucleus. Recent studies demonstrate that human sperm chromatin has an elaborate multilevel organisation, but almost nothing is known about how sperm chromosomes are transformed during fertilisation.