Development of the human bodyDevelopment of the human body is the process of growth to maturity. The process begins with fertilization, where an egg released from the ovary of a female is penetrated by a sperm cell from a male. The resulting zygote develops through mitosis and cell differentiation, and the resulting embryo then implants in the uterus, where the embryo continues development through a fetal stage until birth. Further growth and development continues after birth, and includes both physical and psychological development that is influenced by genetic, hormonal, environmental and other factors.
Development aidDevelopment aid is a type of foreign/international/overseas aid given by governments and other agencies to support the economic, environmental, social, and political development of developing countries. Closely related concepts include: developmental aid, development assistance, official development assistance, development policy, development cooperation and technical assistance. It is distinguished from humanitarian aid by aiming at a sustained improvement in the conditions in a developing country, rather than short-term relief.
Income and fertilityIncome and fertility is the association between monetary gain on one hand, and the tendency to produce offspring on the other. There is generally an inverse correlation between income and the total fertility rate within and between nations. The higher the degree of education and GDP per capita of a human population, subpopulation or social stratum, the fewer children are born in any developed country. In a 1974 United Nations population conference in Bucharest, Karan Singh, a former minister of population in India, illustrated this trend by stating "Development is the best contraceptive.
Fertility tourismFertility tourism (also referred to as reproductive tourism or cross border reproductive care) is the practice of traveling to another country or jurisdiction for fertility treatment, and may be regarded as a form of medical tourism. A person who can become pregnant is considered to have fertility issues if they are unable to have a clinical pregnancy after 12 months of unprotected intercourse. Infertility, or the inability to get pregnant, affects about 8-12% of couples looking to conceive or 186 million people globally.
Fertility and intelligenceThe relationship between fertility and intelligence has been investigated in many demographic studies. There is evidence that, on a population level, measures of intelligence such as educational attainment and literacy are negatively correlated with fertility rate in some contexts. However, genetic studies have shown no evidence for dysgenic effects in human populations. Theories about dysgenic and eugenic effects in human populations have historically been associated with scientific racism.
PloidyPloidy (ˈplɔɪdi) is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively, in each homologous chromosome pair, which chromosomes naturally exist as. Somatic cells, tissues, and individual organisms can be described according to the number of sets of chromosomes present (the "ploidy level"): monoploid (1 set), diploid (2 sets), triploid (3 sets), tetraploid (4 sets), pentaploid (5 sets), hexaploid (6 sets), heptaploid or septaploid (7 sets), etc.
Age and female fertilityFemale fertility is affected by age and is a major fertility factor for women. A woman's fertility is in generally good quality from the late teens to early thirties, although it declines gradually over time. Around 35, fertility is noted to decline at a more rapid rate. While many sources suggest a more dramatic drop at around 35, this is unclear, since few studies have been conducted since the 19th century. One 2004 study of European women found fertility of the 27–34 and the 35–39 groups had only a four-percent difference.
SpermatogenesisSpermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testis. This process starts with the mitotic division of the stem cells located close to the basement membrane of the tubules. These cells are called spermatogonial stem cells. The mitotic division of these produces two types of cells. Type A cells replenish the stem cells, and type B cells differentiate into primary spermatocytes.
