.pn

.pn is the Internet country code top-level domain (ccTLD) for the Pitcairn Islands.

The top-level domain was the subject of a dispute in 2000, between islander Tom Christian—who had been delegated with management of the domain by ICANN—and the government of the island. The dispute was resolved by ICANN ruling that the domain be re-delegated to the Pitcairn Island Council.

Subdomains under various two-letter .pn domains are offered as free redirections by popnic.com.

An official .pn domain costs $100/year from the registry. There are relatively few sites using these domains, but examples include ESPN (es.pn), C-SPAN (cs.pn), and Groupon (gr.pn), which each use the domain for URL shortening services.

The .pn domain is also used as part of a Lionsgate marketing campaign promoting the The Hunger Games film series, presenting it as the "official" country code of the fictional nation of Panem, with domains for the Capitol (thecapitol.pn) and the rebellion (revolution.pn).

Second-Level Domain Name

PN

PN may refer to:873881272

Astronomy

Biology

Business and economics

Culture and entertainment

Electronics

Geography

Linguistics

Pronucleus

A pronucleus (plural: pronuclei) is the nucleus of a sperm or an egg cell during the process of fertilization, after the sperm enters the ovum, but before they fuse. Sperm and egg cells are haploid, meaning they carry half the number of chromosomes. The male and female pronuclei don't fuse, although their genetic material does. Instead, their membranes dissolve, leaving no barriers between the male and female chromosomes. Their chromosomes can then combine and become part of a single diploid nucleus in the resulting embryo, containing a full set of chromosomes.

The appearance of two pronuclei is the first sign of successful fertilization as observed during in vitro fertilisation, and is usually observed 18 hours after insemination or ICSI. The zygote is then termed a two-pronuclear zygote (2PN). Two-pronuclear zygotes transitioning through 1PN or 3PN states tend to develop into poorer-quality embryos than ones who remain 2PN throughout development, and may be significant in embryo selection in IVF.