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With few exceptions, animals consume organic material, breathe oxygen, are able to move, reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development. Over 1.5 million living animal species have been described —of which around 1 million are insects —but it has been estimated there are over 7 million ...
A typical precocial mammal has a gestation period almost four times longer than a typical altricial mammal of the same body size. [20] Precocial mammal species generally have greater adult body weights than altricial mammals as precocial mammals have markedly longer gestation periods than altricial mammals. [21]
1 - morula, 2 - blastula 1 - blastula, 2 - gastrula with blastopore; orange - ectoderm, red - endoderm. 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.
[20] Human children, and those of other primates, exemplify a unique combination of altricial and precocial development. Infants are born with minimal eyesight, compact and fleshy bodies, and "fresh" features (thinner skin, small noses and ears, and scarce hair if any). However, this stage is only brief amongst primates; their offspring soon ...
Drawing of the head of a four-week-old human embryo. From Gray's Anatomy. Embryo drawing is the illustration of embryos in their developmental sequence. In plants and animals, an embryo develops from a zygote, the single cell that results when an egg and sperm fuse during fertilization. In animals, the zygote divides repeatedly to form a ball ...
For example, if I have a patient who is 12 months old and is not yet saying simple words like ‘mama’ or ‘dada,’ I am much more concerned about them if they have missed other milestones ...
The word "kitten" derives from the Middle English word kitoun, which in turn came from the Old French chitoun or cheton. [1] Juvenile big cats are called "cubs" rather than kittens; either term (but usually more commonly "kitten") may be used for the young of smaller wild felids, such as ocelots, caracals, and lynxes.
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