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A human fetus, attached to placenta, at three months gestational age. In humans, the fetal stage starts nine weeks after fertilization. [7] At this time the fetus is typically about 30 millimetres (1 + 1 ⁄ 4 in) in length from crown to rump, and weighs about 8 grams. [7] The head makes up nearly half of the size of the fetus. [8]
Lanugo. Lanugo is very thin, soft, usually unpigmented hair that is sometimes found on the body of a fetus or newborn. It is the first hair to be produced by the fetal hair follicles, and it usually appears around sixteen weeks of gestation and is abundant by week twenty. It is normally shed before birth, around seven or eight months of ...
Echidnas are medium-sized, solitary mammals covered with coarse hair and spines. [6] The spines are modified hairs and are made of keratin, the same fibrous protein that makes up fur, claws, nails, and horn sheaths in animals. [2] Spines of the echidna. Superficially, they resemble the anteaters of South America and other spiny mammals such as ...
Homo sapiens × Pan troglodytes. The humanzee (sometimes chuman, manpanzee or chumanzee) is a hypothetical hybrid of chimpanzee and human, thus a form of human–animal hybrid. Serious attempts to create such a hybrid were made by Soviet biologist Ilya Ivanovich Ivanov in the 1920s, [1] and possibly by researchers in China in the 1960s, though ...
The human body, apart from areas of glabrous skin, is covered in follicles which produce thick terminal and fine vellus hair. Most common interest in hair is focused on hair growth, hair types, and hair care, but hair is also an important biomaterial primarily composed of protein, notably alpha-keratin.
Embryology (from Greek ἔμβρυον, embryon, "the unborn, embryo "; and -λογία, -logia) is the branch of animal biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos and fetuses. Additionally, embryology encompasses the study of congenital disorders that occur before birth ...
Hyraxes are well-furred, rotund animals with short tails. [3] Modern hyraxes are typically between 30 and 70 cm (12 and 28 in) in length and weigh between 2 and 5 kg (4 and 11 lb). They are superficially similar to marmots, or over-large pikas, but are much more closely related to elephants and sea cows. Hyraxes have a life span from 9 to 14 years.
Human embryonic development covers the first eight weeks of development, which have 23 stages, called Carnegie stages. At the beginning of the ninth week, the embryo is termed a fetus (spelled "foetus" in British English). In comparison to the embryo, the fetus has more recognizable external features and a more complete set of developing organs.